Well Completion And Operations

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Well Completion and Operations

Well completion and operations Sfax, June 2010

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Course plan 1. Basic well completion design and practices 2. Formation-wellbore communication, Sand control 3. Downhole completion equipment: • Packer selection and tubing forces • Tubing design and selection: Materials selection, Corrosion and erosion • flow control equipment and subsurface safety valves 4. Wellhead and chokes MMA

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Course plan 5. Well performance: nodal analysis, inflow and tubing performance 6. Deviated, multiple zone, subsea, horizontal, multilateral and HPHT completion considerations 7. Perforating design 8. Causes and prevention of formation damage 9. Stimulation design considerations 10. Wireline, coiled tubing and Snubbing 11. workover rig operations MMA

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Basic well completion design and practices

Petroleum production Petroleum production involves two distinct but intimately connected general systems: • the reservoir, which is a porous medium with storage and flow characteristics, • the artificial structures, which include the well, bottomhole, wellhead assemblies, the surface gathering, separation, and storage facilities. MMA

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Basic well completion design and practices

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Basic well completion design and practices

Completion: - It is the process of making a well ready for production (or injection). - All operations after well drilling up to putting the well on stream. - It is mainly the design, selection and installation of tubular, tools and equipment located in the wellbore for the purpose of conveying, pumping or controlling production or injection fluids. MMA

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Basic well completion design and practices

It includes : • Establishing communication between the reservoir and the borehole. • Design and installation of the production (or injection) string. • Installing the production (or injection) wellhead. MMA

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Basic well completion design and practices Production Wellhead – Xmas tree

Production String

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Basic well completion design and practices

The production string 1. Transfers safely and efficiently the effluent from bottom to surface 2. Allows access to the reservoir for measurement and monitoring. 3. protects the casing from corrosion and erosion MMA

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Basic well completion design and practices

Factors influencing completion design: • Well purpose: exploration, appraisal, development, … • Well type: producer, injector, monitoring well. • Reservoir: petrophysical and physical properties, fluids nature, layers, ...

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Basic well completion design and practices

Factors influencing completion design: (cont’d)

• Operating condition: surface facilities, natural flow, artificial lift, • Environment: supplies, safety rules, … • Well profile: casing, deviation, …

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Basic well completion design and practices

Completion design Well Completion depends on • Reservoir characteristics: - Pressure - Productivity or Injectivity index - Fluids properties - Rock properties and geological data - Fluid temperature • Number of producing zones MMA

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Basic well completion design and practices

Completion design Well Completion depends on (cont’d) • Operational constraints - Environmental regulations - Safety aspects • Geographical factors - Location - Water depth for offshore wells - Weather conditions - Accessibility MMA

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Basic well completion design and practices

Completion design Objectives : • Optimum production \ injection performance • Ensure safety • Maximize the integrity and reliability • Minimize the total cost • Others (sand control, corrosion, etc.) MMA

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Basic well completion design and practices

Completion design How to design a completion? • high rate, • low maintenance, • trouble-free, • economical COMPROMISES MMA

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Basic well completion design and practices

Completion design Horizontal Well • Orientation relative to horizontal stresses – Towards max horizontal stress – Perpendicular to natural fractures • Away from contacts – GOC /OWC • Perforating – Orientation: 0 & 180‟ modified by practical circumstances – Not whole length MMA

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Basic well completion design and practices

Completion design Horizontal Well • Liner – Pre-perforated? – High torque / High Compression Connections? – Solid Centralizers • Sand Control – Stand-alone / Gravel Pack? – Variability in sand properties MMA

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Basic well completion design and practices

Completion design Horizontal Well • Production Logging – CT Locator? • Flow profile – Stability – Artificial Lift

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Basic well completion design and practices

Completion design

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Materiel selection

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Basic well completion design and practices

Completion design Guide to property levels required in elastomer grades For various sealing pressure ranges

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Basic well completion design and practices

Completion design • The effect of a chemical reaction doubles for every 10°C temperature rise. • The lifetime roughly doubles for every 10°C drop. • Make sure that the upper temperature is within the capability of the seal material. • The seal material must be compatible with the fluid environments. • Do not use Zinc Bromide (ZnBr) brine with Nitriles. MMA

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Basic well completion design and practices

Completion design • Be careful with Vitons if amine inhibitors are present, it may be better to use Aflas. • Methanol can affect Vitons, use Aflas or Nitrile if possible. • Do not use EPDM where hydrocarbons are present. • For really aggressive, hot and sour conditions, the best choice is the expensive Kalrez (to 260°C) or Chemraz (20% cheaper and better properties over ~20° to 230°C). MMA

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Basic well completion design and practices

Completion design • Pressure level dictates the mechanical properties required • Critical pressure for blistering is Pb = 5E/6 where E = Young's Modulus (at service temperature). • Critical pressure for rupture is Pr = 4(Lb × Sb)/3 where: Lb: extension ratio at break (length of stretched material per unit initial length) Sb: stress at break (at service temperature) MMA

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Formation-wellbore communication

Wellbore completion concept: Based on the reservoir characteristics: formation type and consolidation, petrophysics properties, completion type, etc. the borehole is equipped as follows: • Barefoot (open hole). • Cased with perforated liner or screen • Cased, cemented and perforated.

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Formation-wellbore communication

Barefoot Completion • Barefoot completion is open hole completion. Casing is set just above the reservoir. • it is cheap and simple to operate, and • hydrocarbons will flow into the bore hole throughout its 360° circumference (radial flow). MMA

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Formation-wellbore communication

Barefoot Completion • Advantages. - Less rig time - Full diameter hole - No perforation, production casing, cementing and logging.

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Formation-wellbore communication

Barefoot Completion • Disadvantages. - No selectivity for production stimulation and workover (new alternatives) - Liable to “sand out” - Ability to isolate is limited to the lower part of the hole

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Formation-wellbore communication

Uncemented Liner Completion • Placing an uncemented liner across the reservoir is the next least expensive completion type. • Casing is run to the top of the reservoir, then a slotted liner is hung off the casing through the reservoir. The liner is not cemented. MMA

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Formation-wellbore communication

Uncemented Liner Completion • This type of completion is attractive in directional wells. • The liner will help prevent hole collapse • The slots provide some sand control • Production through 360° is still achieved MMA

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Formation-wellbore communication

Uncemented Liner Completion • Advantages - No perforation or cementing for the production casing and logging - Less rig time - Assists in preventing sand production

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Formation-wellbore communication

Uncemented Liner Completion • Disadvantages - No selectivity for production stimulation and workover - Difficult to isolate zones for production control purposes - Slightly longer completion time compared to open hole completions MMA

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Formation-wellbore communication

Cased, Cemented and Perforated Completion • the most common configuration for the pay zone-borehole connection is the cased hole. • Casing is primary used to sustain the formation. • Cemented casing will allow to selectively produce zones. MMA

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Formation-wellbore communication

Cased, Cemented and Perforated Completion • It is the most common, because of its ability to effectively isolate the drilled formations and produce them selectively • The hole could be covered with a casing (extended to the surface), or with a short casing called casing liner. MMA

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Formation-wellbore communication

Cased, Cemented and Perforated Completion Advantages - Introduces flexibility allowing isolation of zones and selection of zones for production and/or injection

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Formation-wellbore communication

Cased, Cemented and Perforated Completion Disadvantages - Requires logging & log interpretation to specify the actual perforation zones - Cost of casing, cementing, logging and perforating Rig time

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Sand Control If free sand is available in a formation, it could be produced with fluids causing: • erosion of downhole and surface equipment • filling up surface separators and storage tanks • caving formation • increased costs for sand disposal.

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Sand Control • To prevent producing sand, screens are used to filter the produced fluid. • Well screen could be run in open hole or inside perforated casing MMA

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Sand Control • Usually the annulus behind the screen is filled with a specially sized, highly permeable sand, called gravel • The gravel pack filter fluids and stop sand

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Sand Control Screen with gravel pack:

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Well Completion and Operations

Packer selection Packers and accessories Packer: A device for sealing off the annular space between the tubing and the casing. It is used for: • Casing protection • Separation of multiple zones • Gas lift installations MMA

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Packer selection Packers and accessories Packer consists essentially of an inside passage for fluids, a holding or setting device, and a sealing device. § Sealing element § Slips

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Packer selection Packers and accessories • A cone is driven behind a tapered slip to force the slip out and into casing wall • The packing element is compressed to affect a seal against casing wall

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Packer selection Packers and accessories Packers are classified according to: § Configuration: single, dual. § Use: production, injection, squeeze. § method of setting: mechanical (wire line or DP setting tool) or hydraulic (tubing set) § Retrievable (with tubing or retrieving tool) or permanent (removable by milling or drilling out) WCO -P1_2010 -V0

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Packer selection Packers and accessories Packers types: §

RETRIEVABLE PACKERS -

§

Mechanical set packers - Weight set packers - Tension set packers - Rotational set packers Hydraulic set packers

PERMANENT PACKERS

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Packer selection Packers and accessories Permanent Packers • Setting Ø Wireline setting - The packer is run in hole with electrical wireline setting tool, - The setting tool includes an adapter kit and pressure setting assembly - Electric current ignites a powder charge within the setting tool MMA

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Packer selection Packers and accessories Permanent Packers • Setting Ø Wireline setting - Gas pressure transmits the setting force to the packer - The packer is set and a release stud is sheared, freeing the setting assembly from the packer. - the setting assembly is then removed from the well MMA

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Packer selection Packers and accessories Permanent Packers • Setting Ø Tubing / Drill Pipe setting - Hydraulically - Hydraulically with upward pull assist - Sequential rotation and upward pull MMA

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Packer selection Packer Selection Permanent Packers - Wells with high pressure differential - Wells with large tubing load variations - Deep wells

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Packer selection Packers and accessories Permanent Packers

MODEL D™ RETAINER PRODUCTION PACKER

Halliburton • Seal-bore packer • Wireline, DPU (downhole power Unit) or workstring (hydraulic) set

Baker Oil Tools MMA

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Packer selection Packers and accessories For permanent packer § Locator seal assembly: A nipple with sealing units to travel inside the permanent packer, with a stop guard on the top to limit the down stroke.

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Packer selection Packers and accessories For permanent packer. § Anchor seal assembly: is a locator seal assembly with a latch in stead of the stop guard to fix firmly the string to the packer.

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Packer selection Packers and accessories For permanent packer § Seal units: extensions of the locator with seals to travel within a packer bore and/or extensions

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Packer selection Packers and accessories Hydraulic - Set Packers Ø Setting - Induced fluid pressure drives the cone behind the slips to set them - Slips remain set by either entrapped pressure or a mechanical lock Ø Retrieving - Mostly by picking up on tubing - Some require tubing rotation MMA

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Packer selection Packers and accessories Hydraulic Set Packers

Retrieving Position

Running Position

Set Position MMA

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Packer selection Packers and accessories Retrievable hydraulic Packers

Halliburton RH Single completion packer Hydraulically set Retrieved by straight pull WCO -P1_2010 -V0

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Packer selection Packers and accessories Retrievable hydraulic Packers Halliburton RDH l DualDual-completion packer l Hydraulically set l Retrieved by straight pull l Available with multiple tubing size combinations WCO -P1_2010 -V0

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Packer selection Packers and accessories Retrievable hydraulic Packers Model FH™ FH™ Hydrostatic set Single string Retrievable packer

Baker Oil Tools MMA

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Model AA-5™ dual String retrievable Packer

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Packer selection Packers and accessories Hydraulic - Set Packers Ø Selection - Excellent for deviated or crooked holes - Production tubing can be run in the well and wellhead installed, before setting packer - Multiple completion strings can be landed simultaneously MMA

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Packer selection Packers and accessories • For hydraulically set packer : Hydro-trip pressure sub: a sub with a ball seat, run below a hydraulically set packer to set it.

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Packer selection Tubing forces • Axial Forces : For anchored tubing axial forces are the sum of: §the axial forces induced if the tubing were free to move plus, §the axial forces created by resisting the overall length change.

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Packer selection Tubing forces • Tubing weight • Pressure Acting on Exposed Tubing Areas • Piston Effect (due to plug, expansion device, crossover etc.) • Temperature Effects • Poisson Effect - Ballooning • Slack-off and Over Pull

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Packer selection Tubing forces • Axial Forces : Software packages such as WS-Tube, calculate first the movements as if the tubing were free to move and then calculate the force, using Hooke's law: σ=E×ε E is the constant of proportionality called the modulus of elasticity or Young's modulus (approximately 30 x 106 psi for steel).

σ Stress MMA

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Packer selection Tubing forces • Weight Force : FWT = W cos A N = W sin A FWT = W' TVD Where W = weight of the tubing, lb. W' = tubing weight per unit length, lb/ft TVD = vertical distance below the point of interest to the bottom of the tubing. MMA

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Packer selection Tubing forces • Pressure acting on exposed tubing area: FB = −p (Ao − Ai) Where p = pressure at the bottom of the string, psi Ao = area corresponding to the nominal pipe OD, in2 Ai = area corresponding to the nominal pipe ID, in2 WCO -P1_2010 -V0

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Packer selection Tubing forces • Piston Effect (due to plug, expansion device, crossover etc.) ∆L= L F / E (Ao − Ai)

• Temperature Effects FTEMP = - CT E ∆T (Ao − Ai)

• Poisson Effect - Ballooning FBAl = 2µ (Ai ∆Pi − Ao ∆Po)

• Fluid Friction FFR = − ∆P Ai L / ∆L

• Slack-off and Over Pull Fso = ∆Lso E (Ao − Ai) Lp MMA

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Downhole completion equipment Tubular components • Tubing: § relatively small-diameter pipe that is run into a well to serve as a conduit for the passage of oil and gas to the surface. § Tubing joints are connected together by threaded connections, § they constitute the essential part of the production string (about 99 %). MMA

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Downhole completion equipment Tubular components • Tubing: § API Spec. 5CT fixes geometrical and physical characteristics of tubing and gives chemical composition for low alloy steel used for manufacturing them. § Special tubing connections and alloys are available from some manufacturer but they are not API standard. MMA

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Downhole completion equipment Tubular components Tubing specifications • Nominal size: is the tubing body OD. • API Spec. 5CT fixes nine sizes for tubing: 1.050", 1.315", 1.660", 1.900", 2-⅜", 2-⅞", 3-½”, 4" et 4-½”

• The most common sizes are: 2-⅜", 2-⅞", 3-½” and 4-½”.

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Downhole completion equipment Tubular components Tubing specifications • Grade: is the steel grade, defined by API Spec 5 CT by • a letter (C, J, L, N, …) which characterize the chemical composition and sometimes the thermal treatment. • a figure following the letter which expresses the minimum body yield stress in 1000 psi. • The most common API grades for tubing are: J55, C75, L80, N80, C90 and P105. MMA

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Downhole completion equipment Tubular components Tubing specifications • Length is the length of a tubing joint including the coupling and excluding the pin thread. • The API specifies two lengths for tubing • Range I: 20 - 24 ft • Range II: 28 – 32 ft • Range III defined by API for casing only is used also for tubing mainly for large size (3-½” and above). MMA

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Downhole completion equipment Tubular components Tubing specifications • Weight is the average linear weight of the tubing, weight of connection included, expressed in lb/ft. The most common weights are: § 4.6 / 4.7 lb/ft for 2-⅜" § 6.4 / 6.5 lb/ft for 2-⅞" § 9.2 / 9.3 lb/ft for 3-½” § 12.6 /1 2.75 lb/ft for 4-½” MMA

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Downhole completion equipment Tubular components Tubing specifications • Grade: is the steel grade, defined by API Spec 5 CT by • a letter (C, J, L, N, …) which characterize the chemical composition and sometimes the thermal treatment. • a figure following the letter which expresses the minimum body yield stress in 1000 psi. • The most common API grades for tubing are: J55, C75, L80, N80, C90 and P105. MMA

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Downhole completion equipment Tubular components • Steel grades as per API Spec 5 CT: Yield Strength (kpsi)

40 55 80 90 95 110 125 MMA

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API Grade

H40 J55, K55 N80, L80/Type1 L80/13Cr C90 C95, T95 P110 Q125 WCO -P1_2010 -V0

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Downhole completion equipment Tubular components Steel grades § Carbon steel and low alloys are defined by API Spec and used for completion tubular. § Special alloys are available for sour service and special applications. They are widely used as follows: § 9 Cr for H2S service, § 13 Cr for CO2, § 22 Cr and higher for CO2 + H2S. MMA

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Downhole completion equipment Tubular components • Steel Grade: API Spec 5 CT steel grades

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Downhole completion equipment Tubular components • Steel Grades: • Low alloy steels include §

§

§

§

1% chrome (Cr) to increase hardness and

resistance to corrosion, wear and high temperature 0.2 % molybdenum (Mo) to improve surface hardness and corrosion and wear resistance 1.75 % nickel (Ni) to improve corrosion and mechanical resistance

They are also used for manufacturing completion equipment. WCO -P1_2010 -V0

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Downhole completion equipment Tubular components • Steel grades: • Corrosion Resistant Alloys (CRA) • Semi-stainless steel alloys: 4340, 9% Cr + 1% Mo: suitable for H2S (stress corrosion cracking SCC), acceptable for CO2 and chlorides below 150°F • Martensitic (AISI 410) 13% Cr suitable for H2S (SCC) and chlorides, good resistance to CO2 below 150°F, medium resistance to chlorides below 300°F

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Downhole completion equipment Tubular components • Steel grades: • Corrosion Resistant Alloys (CRA) • Austenitic / ferric (AISI 304, 316, 440): 15-24% Cr; 8-22% Ni; 2% Mn, high resistance to CO2, medium resistance to H2S, affected by chlorides above 150°F. Used in corrosive wells at low temperature MMA

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Downhole completion equipment Tubular components • Steel grades: • Corrosion Resistant Alloys (CRA) • Duplex steel: Cr 22%, 25%, 28%; 32% Ni, used for tubular where high mechanical and corrosion resistances are required • Exotic alloys (high % Chrome): Monel, Inconel. Very high resistence to CO2 corrosion and H2S and chlorides SCC. Used for SSV and pumps valves. MMA

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Downhole completion equipment Tubular components • Steel grades: • Corrosion Resistant Alloys (CRA) • Super alloys: Hastelloy for tubular in severe conditions, Pyromet 31 for SSSV, tools, nipples and MP35N for wireline

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Downhole completion equipment Tubular components • Steel grades: • Corrosion Resistant Alloys (CRA)

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Downhole completion equipment Tubular components • Steel grades:

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Downhole completion equipment Tubular components • Steel grades:

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Downhole completion equipment Tubular components • Steel grades:

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Downhole completion equipment Tubular components • Steel grades: In summary § Carbon steel and low alloys are defined by API Spec and used for completion tubular. § Special alloys are available for sour service and special applications. They are widely used as follows: § 9 Cr for H2S service, § 13 Cr for CO2, § 22 Cr and higher for CO2 + H2S. MMA

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Downhole completion equipment Tubular components Tubing specifications Connection: tubing are screwed together through connections, which could be : § Part of the pipe body:

Integral joint MMA

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Flush joint

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Downhole completion equipment Tubular components Tubing specifications Connection: tubing are screwed together through connections, which could be : § Or coupling: a collar with internal threads used to join two sections of threaded pipe

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Downhole completion equipment Tubular components Tubing specifications Thread: is cut at the pipe end: § On a forged metal pipe end with increased wall thickness and diameter, called upset. It is usually an External Upset End (EUE)

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Downhole completion equipment Tubular components Tubing specifications Thread: is cut at the pipe end: § Or on a flush body end, It is a Non Upset End (NUE)

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Downhole completion equipment Tubular components Tubing specifications Thread: different types are available. They have different shapes, forms and features suitable for different usage. The most used are: § API round thread: - 8 thread / inch for EUE and - 10 thread / inch for NUE. § Vam family: New Vam, Vam Ace, … § Hydril family: HCS, H95, … MMA

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Downhole completion equipment Tubular components Tubing specifications • Connection seal: is ensured in different ways: § API connections rely upon the thread compound (grease), to seal off the leak path between the threads, which is sufficient for low pressure only.

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Downhole completion equipment Tubular components Tubing specifications • Connection seal: is ensured in different ways: § various manufacturers have developed and patented their own connections designed to contain high pressure gas, and often called premium or metal-tometal seal connections, MMA

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Downhole completion equipment Tubular components Tubing specifications • Premium connections:

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Downhole completion equipment Tubular components Selecting Tubing Connectors Criterion: contain well fluid at the maximum anticipated pressure. - Premium Connections for: • all offshore oil wells • deep & high pressure land oil wells • all gas wells - API for: • onshore low pressure wells • pumping wells (EU) - Large price differences exist. MMA

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Downhole completion equipment Tubular components Other tubing characteristics • The drift gives the maximum OD of any equipment to run through the tubing string, and hence it is a foremost parameter. It is the diameter of a 42” long mandrel that passes through tubing joint. • Wall thickness: is a result of the OD and the weight. MMA

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Downhole completion equipment Tubular components Other tubing characteristics • Internal diameter (ID): is a result of the OD and the wall thickness, and it is used to calculate pressure losses and velocities. • Maximum outside diameter: it depends on the nominal diameter and the connection type. It is critical as it determines the strings size that can run in a given casing. MMA

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Downhole completion equipment Tubular components Other tubing characteristics • Mechanical characteristics: deduced from nominal size, weight and grade: § Collapse resistance is the maximum differential pressure applied from outside, that the tubing withstand without permanent deformation. § Internal yield pressure or burst resistance is the maximum internal differential pressure that will cause a tubing to fail. MMA

OGIM

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97

Well Completion and Operations

Downhole completion equipment Tubular components Other tubing characteristics • Mechanical characteristics: deduced from nominal size, weight and grade: § Joint yield strength or tensile strength is the greatest longitudinal stress that the joint can bear without tearing apart.

MMA

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98

Well Completion and Operations

Downhole completion equipment Tubular components • Special tubing: § Fiberglass tubing: is used in low pressure, shallow wells and as a tail pipe below the squeeze packer or for setting cement plugs. They are corrosion resistant and easily drillable. § Internally coated tubing for highly corrosive effluent. Coating is damaged mechanically by tools run inside the production string. MMA

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99

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Downhole completion equipment Tubular components Choosing tubing It is made on the basis of the following parameters: § the expected flow and its expected evolution and the production casing size, to fix tubing nominal size. § The stresses the tubing has to withstand during production and operations, and the effluent type, to choose the grade of steel, the weight and the type of connection. MMA

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Well Completion and Operations

Downhole completion equipment Tubular components • Pup joint: section of pipe less than 20 ft (range I) long. Tubing pup joints are used to space out the string, or adjust distance between downhole equipment. Usual lengths are 2 ft, 3 ft, 5 ft and 10 ft. • Blast joint: joint pup joint with thick wall and hardened external surface. It is run in front of perforations. Usual lengths are 5 ft and 10 ft. MMA

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Well Completion and Operations

Downhole completion equipment Tubular components • Flow Coupling is a heavy walled tubing coupling used to reduce the internal erosion effects caused by disturbances in the production flow stream. They are normally installed above and below safety valves, production profile nipples, sliding sleeves, etc. Lengths: 3, 4 and 6 ft. MMA

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102

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Downhole completion equipment Tubular components • Perforated pup joint: a ported production tub used as an alternative path for wireline measuring devices. • Wireline entry guide: a flaredend sub run on the end of the tubing string to guide back wireline tools into the tubing. Could be also a half mule shoe, which is a cutoff pup joint. MMA

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Well Completion and Operations

Flow control equipment • Sliding side door: a device run as part-of a tubing string which can be opened or closed by wireline methods to provide communication between tubing and casing. Basically it consists, of a ported tubing nipple in which a slotted inner sleeve can be shifted to open or close it. MMA

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Well Completion and Operations

Flow control equipment • Sliding side door:

MMA

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105

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Well Completion and Operations

Flow control equipment • Landing Nipple: receptacle in a production string Internally profiled with: • locking and locating recesses • polished bore in which a mandrel with various types of plugs or valves can be landed, locked and sealed, by wireline method. MMA

OGIM

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Well Completion and Operations

Flow control equipment • Landing Nipple: The landing nipple profile

MMA

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Well Completion and Operations

Flow control equipment • Landing Nipple: A lock mandrel is run with wireline and set inside the landing nipple It is carrying control devices: plugs, valves, chokes, etc.

MMA

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Flow control equipment • Landing Nipple

BOTTOM BLANKING PLUG

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Flow control equipment

Top No-go

• Landing Nipple: can be classified into 3 basic designs - Top No-go - Bottom No-go -

Bottom No-go MMA

OGIM

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110

Well Completion and Operations

Flow control equipment • Landing Nipple: can be classified into 3 basic designs - …. - Selective Nipples Selective Nipple

MMA

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Flow control equipment Landing Nipple are used for: • Plugging the tubing for: • Pressure testing • Setting hydraulic packers • Isolating the tubing, • Zonal isolation • Installing flow control equipment: • Downhole chokes, regulators, SSSV’s • Bottom hole pressure recorder MMA

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Well Completion and Operations

Flow control equipment Bottom-hole Chokes and Regulators • Used to: - Restrict fluid flow in tubing to prevent freezing of surface controls and lines - Maintain reasonable (workable) surface pressure in high-pressure wells - Installed and retrieved by wireline

MMA

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Flow control equipment Bottom-hole Chokes and Regulators

Bottom Choke Circulating Bottom Choke MMA

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Flow control equipment Subsurface safety valve: • An automatic valve installed in the production tubing below the wellhead and designed to prevent uncontrolled flow when actuated. It is commonly abbreviated SSSV. MMA

OGIM

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • It shuts in well down hole when surface control equipment are damaged or removed. • In closed position it prevents well from flowing but it allows pumping down. MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • There are two types of Sub Surface Safety valves: • The Sub Surface Controlled Sub Surface Safety Valve or SSCSSV. § and the Surface Controlled Sub Surface Safety Valve or SCSSV.

MMA

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Flow control equipment Subsurface safety valve: SSCSSV are wireline run and retrieved, and set in landing nipple using locking device They are pressure actuated with: § differential pressure through the valve: a coil spring holds the valve open until well flow rate reaches a predetermined value, the differential pressure exceeds the spring tension and the valve closes § or pressure from above the valve. MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • SSCSSV :

MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • Performance of SSCSSV depends on: - TBG size, - depth, - Temperature, - production rate, - Wellhead flowing pressure, - GOR, - Specific gravity MMA

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Flow control equipment Subsurface safety valve: SSCSSV • Advantages: - Simple construction and operating principle - Easy installation and retrieval - Cheaper installation cost • Disadvantages - Not 100% reliable - Performance could be affected due to solid deposition - Testing of valve operation is not easy MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: SCSSV: § Valves are spring – loaded in the closed position; § They are opened and kept open by applying hydraulic pressure through the control line. § Valve closes when pressure is released MMA

OGIM

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Well Completion and Operations

Flow control equipment Subsurface safety valve: SCSSV: § They are controlled by a hydraulic line connecting the valve landing nipple to a surface control manifold • Two types exist: - Wireline retrievable - Tubing retrievable or tubing integral MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • Wireline retrievable SCSSSV. • The safety valve is run and retrieved with wireline. • It is set in the LN with a lock mandrel.

MMA

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Well Completion and Operations

Flow control equipment Subsurface safety valve: • Wireline retrievable Surface Controlled SSSV. § A ported landing nipple with external control line connection is run within the completion string, usually by 500 to 1000 ft § A Stainless steel ¼” control line is run along the tubing to the surface and attached to it. MMA

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125

Well Completion and Operations

Flow control equipment Subsurface safety valve: Wireline retrievable SCSSV Ø Main advantages: - Easily and economically retrieved for inspection and repair Ø Main disadvantages - Creates restriction to flow and - Can cause plugging or paraffin problems MMA

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126

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Well Completion and Operations

Flow control equipment Subsurface safety valve: Tubing retrievable Surface Controlled SSSV. § The body of the valve is an integral part of the production string. § Similar operation as wireline retrievable type: remote controlled (opened) from surface with hydraulic pressure through a stainless steel ¼” control line. MMA

OGIM

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127

Well Completion and Operations

Flow control equipment Subsurface safety valve: Tubing retrievable Surface Controlled SSSV. Ø Main Advantages: - Full opening design - no restriction to flow - no plugging or paraffin problems Ø Main Disadvantage: - Need to pull TBG for valve repair or inspection MMA

OGIM

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128

Well Completion and Operations

Flow control equipment Subsurface safety valve: Advantages of (SCSSV) over (SSCSSV) • Larger internal diameters and higher flowrate, • Less affected by sand production • Can run wireline tools through valve • Easily and economically retrieved for inspection and repair • Insensitivity to pressure and fluid surge • Valve operation is independent of wellbore influence • More positive control MMA

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OGIM

Well Completion and Operations

Flow control equipment Subsurface safety valve: Disadvantages of SCSSV vs. SSCSSV • Higher cost • Installation more complicated, • Needs well-trained crews

MMA

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Well Completion and Operations

The production string 1. Transfers safely and efficiently the effluent from bottom to surface 2. Allows access to the reservoir for measurement and monitoring. 3. protects the casing from corrosion and erosion MMA

OGIM

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Well Completion and Operations

The production string 1. Safely and efficiently transfer of effluent • Pressure and flow containment • Annuluses isolation • Downhole closure of the flow string • Circulation capability • Tubing isolation

MMA

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132

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Well Completion and Operations

The production string • Pressure and flow containment within : - Production casing - Production tubing - Wellhead - X-mass tree - Packer

MMA

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Well Completion and Operations

The production string • Annulus isolation - It is achieved with the tubing, the packer and the wellhead - It is required in: § Production wells to avoid annulus heading § Injection wells to protect casing against injection pressures § Production \ injection wells to minimize corrosion risks MMA

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Well Completion and Operations

The production string • Downhole closure is required for most wells in particular: - Gas wells - Offshore wells - Remote wells - High pressure wells • it is generally achieved by SubSurface Safety Valve (SSSV) MMA

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Well Completion and Operations

The production string • Circulation Capability It is required mainly for killing the well and it is achieved as follows: - Through circulation ports between the tubing and annulus • Sliding Side Door (SSD) • Side Pocket Mandrel (SPM) • Ported Nipple • Tubing Punch - By squeezing - Through coil tubing or snubbing unit MMA

OGIM

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136

Well Completion and Operations

The production string • Tubing Isolation - In addition to SSSV a secondary means of isolation will be installed - Useful for removal of SSSV (it can act as one safety factor) - Provision is normally provided deep within the wellbore - Normally a wireline plug and nipple combination is used MMA

OGIM

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137

Well Completion and Operations

The production string 2. Allows access to the reservoir for measurement • Ability to suspend P&T monitoring equipment, generally achieved by installing: - wireline nipple as a component of completion string - Perforated pup joint • Through tubing tools for measurement (production logs) MMA

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138

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OGIM

Well Completion and Operations

The production string 3. Protecting casing from corrosion and erosion • Annular seal: packer being the most common method for that • Use of corrosion inhibitor in the packer fluid.

WCO -P1_2010 -V0

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139

Well Completion and Operations

The production string Production string non-essential functions: 1. Downhole tubing detachment : packer seal locator and anchor, safety joint, tieback stem, … 2. Tubing stresses release: travel or expansion joint, packer seal locator, … 3. Protecting tubing from internal and external erosion: flow coupling, blast joint. 4. Wireline entry guide WCO -P1_2010 -V0

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140

Well Completion and Operations

The production string Production string configurations The tail pipe

MMA

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141

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Well Completion and Operations

The production string Production string configurations Single string: § it is the most common type of completion § It is used mainly for single completion (one production or injection zone) § It is also used for dual completion: one zone producing \ injecting through the string the second zone in the annulus tubing \ casing WCO -P1_2010 -V0

MMA

OGIM

142

Well Completion and Operations

The production string Production string configurations

Single Layer Single Tubing Completion WCO -P1_2010 -V0

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143

Well Completion and Operations

The production string Production string configurations

RESERVOIR A

RESERVOIR B

Double Layer Single Tubing MMA

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144

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Well Completion and Operations

The production string Production string configurations Single completion

WCO -P1_2010 -V0

MMA

OGIM

145

Well Completion and Operations

The production string Production string configurations Single completion with permanent packer

WCO -P1_2010 -V0

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OGIM

146

Well Completion and Operations

The production string Production string configurations Single completion with straddle packer

MMA

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147

49

OGIM

Well Completion and Operations

The production string Production string configurations Multi-string: § The dual string is the most common type of multi-string completion § It is used mainly for dual completion: two zones at different pressures, with different or incompatible effluents, or with different productivities MMA

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Well Completion and Operations

The production string Production string configurations I

II

RESERVOIR A

RESERVOIR B

Double Layer Dual Tubing Completion MMA

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149

Well Completion and Operations

The production string Production string configurations Dual completion with dual packer and single permanent packer

MMA

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150

50

OGIM Well Completion and Operations Equipment of naturally flowing wells

Production string configurations Dual completion with lateral open holes

MMA

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151

Well Completion and Operations

The production string Subsea Completions • Subsea production systems have wells located on the sea floor. • Safety equipments are installed underwater on the seabed. • enable early production from deepwater, remote, and marginal fields • offer a means of producing field extremities not reachable by directional drilling from existing platforms. • Used also when field economics do not justify the installation of one or more additional platforms MMA Completion Subsea

OGIM

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Well Completion and Operations

Production wellhead

MMA

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153

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Well Completion and Operations

Production wellhead • The wellhead is the housings and spools plus valves, hangers and seals in which the casing and tubing strings are supported.

MMA

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154

Well Completion and Operations

Production wellhead tubing head spool

MMA

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155

Well Completion and Operations

Production wellhead • The tubing head spool

MMA

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156

52

OGIM

Well Completion and Operations

Production wellhead tubing head spool

tubing hangers

MMA

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157

Well Completion and Operations

Production wellhead •The production tree, or Christmas tree (X-mass tree) is an assembly of valves and fittings installed as a unit on top of the tubing head. It is used to maintain surface control of a well. MMA

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158

Well Completion and Operations

Production wellhead • Compact Dual Christmas tree

MMA

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159

53

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Well Completion and Operations

Production wellhead • Subsea wellhead

WCO -P1_2010 -V0

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160

Well Completion and Operations

Production wellhead • The valves Gate valve: employs a sliding gate to open or close the passage in it

WCO -P1_2010 -V0

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161

Well Completion and Operations

Production wellhead • The valves actuator Actuator is a mechanism for the remote or automatic operation of a valve or choke Pneumatic actuator MMA

Hydraulic actuator WCO -P1_2010 -V0

162

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Well Completion and Operations

Production wellhead chokes: • restrict the flow diameter and reduce the fluid flow. • At the wellhead, they: • Help to maintain a fixed wellhead pressure and therefore a stabilized production flow • Prevent the surface parameters fluctuations from affecting the well production (supersonic velocity in the choke throat. MMA

OGIM

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163

Well Completion and Operations

Production wellhead • The wellhead Choke: a device installed after the wing valve to regulate the flow rate.

MMA

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164

Well Completion and Operations

Production wellhead Chokes

MMA

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165

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Well Completion and Operations

Production wellhead Chokes

MMA

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166

Well Completion and Operations

Production wellhead

MMA

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167

Well Completion and Operations

Well performance • Hydrocarbons in the reservoir are under pressure from the natural forces that surround and trap it. • If a hole (well) is drilled into the reservoir, an opening is provided at a much lower pressure through which the reservoir fluids can escape. • The driving energy which causes these fluids to move out of the reservoir and into the wellbore comes from the compression of the fluids that are stored in the reservoir. MMA

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168

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Well Completion and Operations

Well performance • The driving energy should overcome the friction losses in the system and to lift the effluent to the surface. • For naturally flowing well the energy to lift the effluent to surface comes from the reservoir pressure • The reservoir pressure shall overcome the hydrostatic pressure in the well and all the pressure losses from reservoir to the surface PR > Δ PBorehole + PH + Δ PString + PWH MMA

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Well Completion and Operations

Well performance • A well is naturally flowing when it has enough energy to push hydrocarbons to the surface.

MMA

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Well Completion and Operations

Well performance • To ensure PR > Δ PBorehole + PH + Δ PString + PWH we can act at different levels: § increase PR: water injection or gas injection in the reservoir, so we are adding energy to the reservoir.

MMA

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171

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Well Completion and Operations

Well performance • To ensure PR > ΔPBorehole + PH + ΔPString + PWH we can act also by reducing ΔPBorehole : Δ PBorehole • uses 10 to 50 % of available pressure. • This pressure drop depends mainly on flow rate, formation permeability and pay zone thickness, fluid viscosity, GLR in reservoir conditions and wells spacing. MMA

OGIM

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Well Completion and Operations

Well performance • To ensure PR > Δ PBorehole + PH + Δ PString + PWH we can also: § reduce (PH + Δ PString) § (PH + Δ PString) is the pressure drop in lifting the fluids from the wellbore to the wellhead through the production string. § It is known as the vertical lift performance (VLP), or the tubing performance relationship (TPR). MMA

OGIM

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Well Completion and Operations

Well performance • reducing (PH + Δ PString) • (PH + Δ PString) the pressure drop in lifting the fluids from the wellbore to the wellhead, is 35 to 98 % of the available wellbore flowing pressure • It depends on flow rate, tubing size and roughness, depth, GLR, P, T, effluent density, etc.

MMA

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Well Completion and Operations

Well performance

• reducing (PH + Δ PString) • reduce Δ PString by increasing the string diameter, whitch has its own limit as production string with large diameter could act as separator and consequently kill the well. • reduce PH: the hydrostatic pressure of the effluent in the production string • reduce PWH: it is fixed by the surface process, and its value is usually very low. MMA

OGIM

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Well Completion and Operations

Well performance • reducing PH PH = H x d /10 To reduce either: § d (density): mixing gas to the well effluent (Gaslift), or § h (the column height): mechanically or hydraulically lifting the well effluent (pumping). MMA

OGIM

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176

Well Completion and Operations

Well performance • To analyze the fluid flow in a system, we cut the system into distinct successive elements (equipment sections). • The intersection of two adjacent elements is called node. • The system analysis for the determination of fluid production rate and pressure at a specified node is called ‘‘Nodal analysis’’ MMA

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Well Completion and Operations

Well performance Nodal analysis is performed on the basis of the following principles: • pressure continuity: only one pressure can exist at a node. • Flow into the node equals flow out of the node

MMA

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Well Completion and Operations

Well performance • In a production system two nodes are always considered: • the wellbore • and the wellhead • Upstream the wellbore node there is the reservoir system, • Down stream the wellbore there is the production string, which is at the same time the upstream of the wellhead node. • Downstream the wellhead node there is the surface facilities system. MMA

OGIM

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Well Completion and Operations

Well performance

MMA

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180

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Well Completion and Operations

Well performance • The flow upstream the wellbore (through the reservoir to the wellbore) is called the inflow. • The flow from the bottom hole upward (down stream the wellbore) is called the outflow. • Inflow and outflow must be equal.

MMA

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Well Completion and Operations

Well performance • Inflow is controlled by reservoir properties (pressure, fluid type and composition, permeability, etc.) • Outflow is controlled by: - Production string (length, diameter, roughness) - Surface separator pressure - Fluid type and composition

MMA

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Well Completion and Operations

Well performance • The IPR (inflow performance relationship) represents the relationship between flowing bottom-hole pressure (Pwf) and the liquid production rate. - The shape of the IPR curve depends on the type of reservoir drive mechanism that produces the liquid. - the derivative (slope) of the IPR curve at Pwf is the PI. MMA

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Well Completion and Operations

Well performance • The relation between pressure and flow in a considered system, is called performance relation. • The plot (P,Q) is the performance relation curve.

WCO -P1_2010 -V0

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184

Well Completion and Operations

Well performance Inflow Performance Curve IPR

PI = slope of IPR curve (BPD/psi)

Ps Pwf

Qtest Qliquid MMA

OGIM

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185

Well Completion and Operations

Well performance PI Equation

PI = q /(Pr - Pwf ) Where: - PI is the productivity index, stbpd/psi - q is liquid production, stbpd - Pr is average reservoir pressure, psia - Pwf is flowing well pressure at perforations, psi Equation is approximate for liquid flow with no free gas from formation (Pr > Pb) MMA

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Well Completion and Operations

Well performance Productivity Index PI • The PI may, and usually does, vary as Pwf changes. • PI is fairly constant for water-drive reservoirs. • PI is changing for dissolved gas drive

MMA

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Well Completion and Operations

Well performance • Factors affecting PI: - Increased free gas saturation near the wellbore as reservoir pressure declines (gas comes out of solution). This lowers relative permeability to oil. - Change of flow regime from laminar to turbulent near wellbore. - Critical flow rate through formation pores (pores act as orifices in choked flow.) MMA

OGIM

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188

Well Completion and Operations

Well performance • Comparative IPR Curves

MMA

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189

63

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Well Completion and Operations

Well performance Tubing Performance

MMA

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190

Well Completion and Operations

Well performance Tubing and IPR

MMA

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191

Well Completion and Operations

Well performance

MMA

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192

64

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Well Completion and Operations

Well performance

MMA

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193

Well Completion and Operations

Well performance

MMA

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194

Well Completion and Operations

Well performance For the production equipment: • Accurate models exist for single phase flow and the characteristic parameters are known or can be easily determined for each component. • For two phase flow, models do exist but experimental closure equations are required (the problem is too complex) and some degree of uncertainty exist in the predictions. MMA

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195

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OGIM

Well Completion and Operations

Well performance For the flow in the reservoir and near wellbore region • Accurate models exist for single phase flow but the characteristic parameters such as permeability and porosity distribution are not known and an “averaged effect” must be determined by a well test. • For two phase flow no simple model exist and the predictions rely on correlations or empirical methods MMA

OGIM

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Well Completion and Operations

Well performance • IPR under multiphase flow conditions can not be easily calculated. • The most accurate method is by solving the equations governing the flow in the porous media through a reservoir simulator. • The IPR is so important to Production Engineers that simplified or empirical methods to estimate it are necessary. • The most common correlations are Vogel and Fetkovich MMA

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Well Completion and Operations

Well performance • Vogel equation

MMA

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198

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Well Completion and Operations

Perforating design Perforation: • a hole made in the casing, cement, and formation establishing communication between the borehole and the formation. • the hole is about ¼” diameter, penetration is 2 to 6 ft,

MMA

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Well Completion and Operations

Perforating design Perforation: • Usually several perforations are made at a time, using a perforation gun. • The perforation gun is a device fitted with shaped charges or bullets that is lowered to the desired depth in a well and fired to create penetrating holes.

MMA

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200

Well Completion and Operations

Perforating design Perforation:

MMA

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201

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Well Completion and Operations

Perforating design Perforation: • There are tubing convoyed and wireline convoyed perforation guns. • Perforation are done after running the production \ injection string, using tubing convoyed gun

MMA

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Well Completion and Operations

Perforating design Perforation:

MMA

OGIM

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203

Well Completion and Operations

Perforating design Perforation: perforation guns

MMA

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204

68

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Well Completion and Operations

Perforating design Perforation: shaped charges

MMA

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OGIM

205

Well Completion and Operations

Perforating design Perforation: shaped charges

MMA

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206

Well Completion and Operations

Perforating design Perforation: The Perforation Process

MMA

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207

69

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Well Completion and Operations

Perforating design Perforation: The Perforation Process • High jet tip velocity 7,000 m/sec • High Impact pressure: millions psi • Short duration: microseconds • Jet at elevated temperature, but not melted (about 500 °C) • About 25 – 30% energy efficient MMA

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Well Completion and Operations

Perforating design Perforation: Halliburton perforation shaped charges

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Well Completion and Operations

Perforating design Perforation:

Perforating Gun Comparison

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OGIM

Well Completion and Operations

Perforating design Perforation: the hole penetration is depending also on the presence of fluid between the charge and the well wall, the thickness of casing and cement and the type and compactness of the formation.

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Well Completion and Operations

Perforating design Perforation: • Perforate in clean, solid free, nondamaging fluid: normally water or oil, with a differential pressure into well bore. • The perforation interval and density depends on pay zone thickness and petrophysical properties. Usually 4 SPF with 90° or 180° phasing are used. MMA

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Well Completion and Operations

Perforating design Perforation design: • It will depend on: • the formation nature and height, • The reservoir characteristics: porosity, permeability, fracture, fault, etc. • The reservoir fluids proprieties: nature, viscosity • the OWC and the GWC.

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Well Completion and Operations

Perforating design Perforation design: • Usually the oil bearing formation (or gas bearing formation for gas wells) is perforated at: • 4 SPF, 90° phased for thin formations • 2 SPF for very thick formations

MMA

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Well Completion and Operations

Causes and prevention of formation damage Fluid Incompatibilities: • Mixing different fluids could create solids precipitation, fluids are said incompatible. • Fluids entering the reservoir formation such as fluids used for drilling muds, well completion, killing the well, stimulation, or fluids produced from different formations and not compatible with the reservoir fluids will precipitate solids inside the reservoir plugging it. • The damage could be permanent if the solids are not soluble (acid, solvents, etc.) MMA

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Well Completion and Operations

Causes and prevention of formation damage Fluid Incompatibilities: • Fluids entering the reservoir formation could also react with the formation (fresh water and formation clay), plugging pores and reducing permeability. • Drilling and milling fluids circulated in front of a reservoir formation should be: • low solid content, • low filtrate and • compatible with reservoir fluids and matrix MMA

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Well Completion and Operations

Causes and prevention of formation damage Fluid Incompatibilities: • Any other fluid pumped in the well and which could enter the reservoir formation should be: • Solid free • Compatible with the formation fluids • Compatible with the formation matrix • In all cases reduce the overpressure on the pay zone, consider underbalanced drilling and milling MMA

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Well Completion and Operations

Causes and prevention of formation damage • Formation could be also damaged by: • Produced solids (sand, silt) in a non consolidated formation. Consider the use of screens, gravel pack, etc. • Solids deposits due to change in petrophysics parameter: P, V, T, composition, etc. entailing a deposit of wax, asphalt, calcium carbonate. • Prevent deposit by staying away from deposit conditions • Treatment with solvent, acid, etc. MMA

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Well Completion and Operations

Causes and prevention of formation damage Acid Damage: • Iron from the tubing/casing dissolves in the acid. As the pH of the spent acid rises, the iron will precipitate out in the formation. To reduce this problem “pickle” the tubing (pump acid down the tubing, then reverse circulate it out).. • If the formation contains oil or an oilbased mud was used, the acid and oil can form an emulsion (accelerated by the dissolved iron). Use surfactants with the acid to prevent emulsion formation. MMA

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Well Completion and Operations

Causes and prevention of formation damage • Pressure Build Up (BU) will determine the skin effect • In case of positive skin effect consider treating. • Treatment will depend on the nature and the extent of the damage, and could be acid wash, chemical treatment, reperforation, etc.

MMA

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Well Completion and Operations

Causes and prevention of formation damage Treatment of damaged formation: • Backflow • Stimulation (acid wash, acidizing) • Re-perforate /Add perforations • Stimulation (fracturation) • Recomplete MMA

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