9 Tubing Tools 15

Chair of Petroleum & Geothermal Energy Recovery

OGPP - Practical Tubing Design / Tools

Clemens Langbauer dongbaosy.en.alibaba.com

Chair of Petroleum & Geothermal Energy Recovery

Agenda - Tubing Stress Analysis -

Material Properties

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Tension

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Collapse

-

Burst

-

Biaxial Design

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Triaxial Design

-

Load Cases

- Packers - Subsurface Safety Valve (SSSV) Page 2

Chair of Petroleum & Geothermal Energy Recovery

Tubing Stress Analysis Tubing is the fundamental component of most completion designs and is a barrier in the well control envelope. Objectives: -

Defines the size, weight and grade of the tubing Design scenarios ensure that the selected tubing will withstand all projected installation and service loads for the life of the well Ensure that through tubing interventions are not adversely affected by stress effects such as buckling Assist the drilling engineers in defining loads for casing stress analysis (gas-lift operations)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Stress – Strain Relationship

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Steel Qualities Carbon Steels Carbon steel is steel in which the main alloying constituent is carbon in the range of 0.12–2.0%. 13 Cr steels 13 Cr steels are stainless steels that does not readily corrode or rust with water as ordinary steel does. Duplex steel Duplex stainless steels are called “duplex” because they have a twophase microstructure consisting of grains of ferritic and austenitic stainless steel. Corrosion – resistant alloys (CRA) A corrosion-resistant alloy (CRA) is an alloy consisting of metals such as: Chrome, Stainless steel, Cobalt, Nickel, Iron, Titanium, Molybdenum Page 5

Chair of Petroleum & Geothermal Energy Recovery

Tubing Grades

Source: Well Completion Design Book

Page 6

Chair of Petroleum & Geothermal Energy Recovery

Tubing Properties

B. Howard: Petroleum Engineers Handbook

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Chair of Petroleum & Geothermal Energy Recovery

Tubing Properties

B. Howard: Petroleum Engineers Handbook

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Chair of Petroleum & Geothermal Energy Recovery

Temperature Dependency The strength of steel (especially of cold-worked alloys) is dependent on Temperature (starting at 70°F) and experience a significant decrease in strength at high temperatures. (During manufacturing, as the material is cold-worked to increase its strength, energy is stored in the material in the form of dislocations. By heating the material, the energy barrier which prevents this return to a lower energy state is overcome and returning it to the pre-deformed state.)

Carbon steel 13Cr Duplex steel

0,03 % / °F 0,05 % / °F 0,1 % / °F

Source: Well Completion Design Book

0,054 % / °C 0,09 % / °C 0,18 % / °C

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Chair of Petroleum & Geothermal Energy Recovery

Temperature Dependency Example Temperature Dependency of the Yield Strength Calculate the reduction of the yield strength of a 125 ksi duplex steel at a temperature of T = 350°F! (1 ksi = 1000 psi)

Page 10

Chair of Petroleum & Geothermal Energy Recovery

Loads on Tubing Axial Loads Axial strength Weight of tubing Piston forces Ballooning Temperature changes Fluid drag Bending stresses Buckling Tubing to casing drag Collapse Elastic collapse Transition between elastic and plastic Plastic collapse Yield collapse Burst Page 11

Chair of Petroleum & Geothermal Energy Recovery

Safety Factors

Source: Well Completion Design Book

Page 12

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Axial Strength Fa,max = Ax . Yp σ=

F Ax

σ F Ax ε E Fa,max Yp

ε=

∆L L

E=

σ ε

… Stress (lbf/in² or psi / Pa) … Load (lb , N) … Area (in², m²) … Strain (-) … Young’s modulus (30.106 psi / 210.109 Pa) … Maximum axial force (lb, N) … Yield stress (psi, Pa)

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example Stress Calculation A 10000 ft long tubing is loaded with an axial load of 300 000 lb. Calculate the stress and the elongation of the 5,5 in, 17 lb/ft tubing! (neglect self-weight) Example

Maximum Axial Force Calculate the maximum axial force a 5,5 in, 17 lb/ft tubing, grade L80 can support!

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Weight of Tubing: Vertical well: (ignoring friction) The whole weight is supported by the tubing hanger Deviated well: (ignoring friction) w . MD l w Fw = . TVD l w Fn = . (MD − l

W=

Lw = Lw w l

TVD)

w l² . l 2EA

… Elongation / self weight … Weight per foot of tubing (lb/ft, N/m)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example Weight of Tubing Generate the load vs. depth profile of the axial load, caused by the self-weight of a 10000 ft long, vertical tubing string in air. 5,5 in, 17 lb/ft Calculate the elongation due to the selfweight of the tubing string!

Source: Well Completion Design Book

Page 16

Chair of Petroleum & Geothermal Energy Recovery

Piston Force Buoyancy: fluid pressure acting on the base of free-hanging tubing Fp = p. Ax p = 0,433. sg. TVD (Field Units)

Example

HW Deadline: 22.10.2014 Buoyancy

10:00

Calculate the axial load of the 5,5 in, 17 lb/ft tubing in sea water (s.g. 1,02) Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Piston Force Pressure testing plugs: Pressure differential across the plug Fp = ∆pplug . Ai ∆L =

∆L

L.∆pplug .Ai E. A0 −Ai

… Elongation (ft, m)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Piston Force Example

HW Deadline: 22.10.2014

10:00

Pressure testing plug Calculate the axial load of a tubing pressure test in a vertical well in seawater. ∆p = 5000 psi Tubing: 5,5 in, 17 lb/ft Plug near base of tubing

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Piston Force

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Piston Force Crossovers: Pressure differential on crossover Fp = −∆pi Api − Ati + ∆po Api − Ato ∆L =

pi po Api Ati Ato Fp

Fp .L E. A0 −Ai

… p in tubing (psi, Pa) … p in annulus (psi, Pa) … Area of packer ID (in², m²) … Area of tubing ID (in², m²) … Area of tubing OD (in², m²) … Force due to piston effect (lb, N)

Source: Well Completion Design Book

Page 21

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Ballooning: Internal pressure swells or balloons the tubing and causes it to shorten. Pressure in the annulus squeezes the tubing, causing it to elongate “reverse ballooning”.

Fb = 2. μ. Ai . ∆pi − Ao . ∆po ∆LBal =

−L.Fb E. Ao −Ai

μ Ai Ao ∆pi ∆po

… Poisson ratio (-) 0,3 in most cases … Tubing inside diameter (in², m²) … Tubing outside diameter (in², m²) … Change of inside pressure (psi, Pa) … Change of outside pressure (psi, Pa)

Source: Well Completion Design Book

Page 22

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example HW Deadline: 22.10.2014

10:00

Ballooning Calculate the ballooning force, resulting from the pressure test for the 5,5 in, 17 lb/ft tubing (no outside pressure). Calculate the movement if the tubing is free hanging.

Source: Well Completion Design Book

Page 23

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Temperature Changes: Thermal expansion or contraction causes a length change in the tubing. ∆Lt = Ct . Lt . ∆T

Ft = − Ct . E. ∆T. Ao − Ai ∆T is the difference between the average temperatures of any two operating modes.

Carbon & 13C steels Duplex steels

Ct

∆Lt Lt ∆T

Ct : 1,1.10-5 1/°C Ct ∶ 1,25.10-5 1/°C

(6.10-6 1/°F) (7.10-6 1/°F)

… Coefficient of thermal expansion (1/°F, 1/°C) … Change in tubing length (ft, m) … Tubing length (ft, m) … Change in average temperature (°F, °C)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example Temperature Effect A vertical completion uses a 2000 meter long 2 7/8” tubing. During the installation the tubing temperature equalizes with the surrounding temperature, given by the following equation: T(d)=1,5.10-5.d² - 0,005.d + 50 °C

(d in m)

Calculate the length change that occurs during the installation of the tubing, if the storage temperature of the pipes is TSurface = 10 °C! (Duplex Steel)

Source: Well Completion Design Book

Page 26

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Fluid Drag: The tubing string is contracted / stretched due to the fluid friction that occurs during production or injection. The direction of the stretch is in flow direction.

FF =

∆p A .L ∆L i

∆LF =

∆p ∆L

FF .L 2E. Ao −Ai

… friction pressure drop (psi/ft, Pa/m)

Source: Well Completion Design Book

Page 27

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example

HW Deadline: 22.10.2014

10:00

Fluid Drag Calculate the friction force of a water injection well with a frictional pressure drop of 90 psi/1000 ft and the elongation if the tubing is free hanging. Tubing: 5,5 in, 17 lb/ft

Source: Well Completion Design Book

Page 28

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Bending Stresses: Caused by bending of the tubing string (e.g. through dogleg)

σb = ±

E.Do π α . . 2.12 180 100

(Field units)

σb = ±

E.Do π α . . 2 180 30

(Si units)

Do E α

… Outside tubing diameter (in, m) … Young's Modulus (psi, Pa) … Dogleg severity (°/100 ft, °/30 m)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example Bending Stresses Assume the buoyant tubing string from the previous example (tubing: 5,5 in, 17 lb/ft, 10000 ft long). Calculate the bending stresses and the bending load, if there is a dogleg of 3°/100 ft from 8000 ft to 10000 ft.

Source: Well Completion Design Book

Page 30

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Buckling: Structural weakness of thin slim elements -

-

High bending stresses and therefore low axial safety factors as well as bending loads on connections Large tubing – to – casing friction force Torque on connection that can unscrew them in extreme cases Shortening of the tubing when buckled Resulting doglegs that can limit through tubing access

Source: Well Completion Design Book

Page 32

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads

Assuming a small initial defection from vertical tubing. Internal pressure acts on both sides of the tubing (inside). The area on the outside of the bend is larger than on the inside. The sideways forces resulting from this pressure will tend to increase the initial bend.

Source: Well Completion Design Book

Page 33

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Compression and internal pressure pi promote buckling, whilst external pressure po and tension reduce the likelihood of buckling. These effects are captured in the term effective tension Feff: Feff = Ftotal + (po . Ao − pi . Ai ) Ftotal Fc

… Total axial load (neglecting bending) … Critical buckling force

Source: Well Completion Design Book

Page 34

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads The effective axial load goes precisely to zero at the base of the tubing, as buoyancy and the pressure component of the effective axial load are equal in magnitude and opposite in sign.

Source: Well Completion Design Book

Page 35

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Critical buckling force / vertical wells: Sinusoidal buckling: Fc = 1,94 . Helical buckling: Fc = 4,05 .

I for tubing = I w

π . 64

3

3

EIw²

EIw²

Do 4 − Di 4

… Momentum of inertia (in4, m4) … Tubing buoyant weight (lb/in, N/m)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Critical buckling force / deviated wells: Sinusoidal buckling: Fc =

4.EIw.sinθ rc

Helical buckling: Fc = 1,41~1,83.

rc

4.EIw.sinθ rc

… radial clearance (in, m) (difference in radius: csg. inside and tbg. outside)

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Tubing to casing drag: Friction factors: Mud 0,15 – 0,25 Water 0,3 – 0,45 Brine 0,2 – 0,3

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Expansion Device

used to reduce stresses on packers and tubing

Source: Well Completion Design Book

Page 40

Chair of Petroleum & Geothermal Energy Recovery

Axial Loads Example Axial Loads In a 3000 meter deep 7” 23 lb/ft, (di=6,366”) casing a 2 7/8” 6,4 lb/ft (9,52 kg/m) tubing J55 and a packer are installed. The annulus is filled with brine s.g. 1,02 (pch=0 MPa). Evaluate the behavior of the tubing if the well is switched after tubing installation and perforation to production (pwf = 40 MPa, s.g. 0,9, 40°C at surface). Calculate the force the packer must support for a fixed tubing and a tubing with expansion device. Check the tension safety factor! Friction pressure losses: 110 psi/ft (2,48 MPa/1000m) TSurface = 10 °C Geothermal gradient = 3 °C/100m Packer setting force = 10000N tension Page 41

Chair of Petroleum & Geothermal Energy Recovery

Collaps API Collapse Formulas: Four formulas (named according to the type of failure) are available for calculating the collapse resistance: - Elastic collapse - Transition between elastic and plastic - Plastic collapse - Yield collapse

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Chair of Petroleum & Geothermal Energy Recovery

Collaps

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Collaps Yield Collapse: Four formulas (named according to the type of failure) are available for calculating the

Source: Applied Drilling Engineering

Page 44

Chair of Petroleum & Geothermal Energy Recovery

Collaps Plastic Collapse: (based on empirical data)

Source: Applied Drilling Engineering

Page 45

Chair of Petroleum & Geothermal Energy Recovery

Collaps Transition Collapse: (obtained by numerical curve fitting between plastic and elastic collapse)

Source: Applied Drilling Engineering

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Chair of Petroleum & Geothermal Energy Recovery

Collaps Elastic Collapse: (based on theoretical instability failure)

Source: Applied Drilling Engineering

elastic

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Chair of Petroleum & Geothermal Energy Recovery

Collaps Example: API Collapse Determine the collapse strength of a 5 ½” 14 lbm/ft J-55 pipe under zero axial loads. (t = 0,244 in)

Page 48

Chair of Petroleum & Geothermal Energy Recovery

Burst API Burst Formulas: Internal pressure is higher than external pressure.

p Yp t D

… minimum internal yield pressure (psi) … minimum yield strength (psi) … wall thickness (in) … Outside pipe diameter (in)

Source: Applied Drilling Engineering

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Chair of Petroleum & Geothermal Energy Recovery

Burst API Burst Example: Calculate the minimum internal yield pressure for a pipe 5”, 15 lbm/ft and grade C-95 (density steel = 0,286 lbm/in³, t = 0,296 in)

Page 50

Chair of Petroleum & Geothermal Energy Recovery

Biaxial Design Collapse and Axial Stress -

The collapse pressure resistance of a pipe depends on the axial stress

-

The collapse resistance of a pipe is reduced when tensional loads are present

-

The collapse resistance of a pipe is increased when compression loads are present

Page 51

Chair of Petroleum & Geothermal Energy Recovery

Biaxial Design Burst and Axial Stress -

The burst pressure resistance of a pipe depends on the axial stress

-

The burst resistance of a pipe is increased when tensional loads are present

-

The burst resistance of a pipe is reduced when compression loads are present

Page 52

Chair of Petroleum & Geothermal Energy Recovery

Biaxial Design

Source: Applied Drilling Engineering

Page 53

Chair of Petroleum & Geothermal Energy Recovery

Biaxial Design Example: Biaxial Collapse Determine the collapse strength for a 5 ½”, 14 lbm/ft, J55 pipe under axial load of 100000 lb!

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Chair of Petroleum & Geothermal Energy Recovery

Triaxial Design Triaxial Analysis The analysis of the axial stress 𝜎𝑎 , radial stress 𝜎𝑏 and tangential stress 𝜎𝑡 is called triaxial analysis.

Von Mises Equivalent:

Source: Well Completion Design Book

Page 55

Chair of Petroleum & Geothermal Energy Recovery

Triaxial Design

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Triaxial Design

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Triaxial Design

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Triaxial Design

Source: Well Completion Design Book

Page 59

Chair of Petroleum & Geothermal Energy Recovery

Load Cases -

Initial conditions

-

Tubing pressure test

-

Annulus pressure test

-

Production

-

Evacuated tubing

-

Tubing leak

-

Injection

-

Pump in to kill

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Load Cases -

Gas lift installation

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Load Cases -

Shut in

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Packers Packers provide a structural purpose and a sealing purpose. Objectives: -

Isolate the annulus to provide sufficient barriers or casing corrosion prevention (production packer) Isolate different production zones for zonal isolation Isolate gravel and sand (gravel pack packer) Provide a repair or isolation capability (e.g. straddle packers) Aid in forming the annular volume required for gas lift Limit well control to the tubing at the surface, for safety purpose Hold well servicing fluids

Source: Well Completion Design Book

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Chair of Petroleum & Geothermal Energy Recovery

Packers

Source: Well Completion Design Book

Page 64

Chair of Petroleum & Geothermal Energy Recovery

Packers Permanent Packer:

Source: Well Completion Design Book

Retrievable Packer:

Page 65

Chair of Petroleum & Geothermal Energy Recovery

Packers Packing loads on Casing: The slips of a packer or anchor will generate an outward (burst) force on casing. This outward force from the slips will try to expand the casing radially.

Fr =

Fa .(1−μ.tan α) μ+tan α

pburst = ∆pcasing + Fr Fa μ α

Fr Slip area

… Friction force (lb / N) … Axial force (lb / N) … Friction coefficient (-) … Cone angle of slips (°)

Source: Well Completion Design Book

Page 66

Chair of Petroleum & Geothermal Energy Recovery

Packers Example Packer Calculate the required friction force and the additional burst pressure to support 100000 N. (6 slips each 80 x 20 mm) μ = 0,45 α = 10°

Source: Well Completion Design Book

Page 67

Chair of Petroleum & Geothermal Energy Recovery

Subsurface Safety Valve SSSV are fail-safe valves that are designed to prevent an uncontrolled release of hydrocarbons from the well if something catastrophic occurs at surface.

Source: Well Completion Design Book

Page 68

Chair of Petroleum & Geothermal Energy Recovery

SSSV Operation Principle: The hydraulic pressure (applied surface pressure, hydrostatic pressure of the control line fluid) in the control line must overcome the spring force to maintain the valve open. If the valve is positioned too deep, the hydrostatic pressure can maintain the valve open even when all surface pressure has been bled off. Dmax =

pvc −pmc g.ρf

Dmax pvc pmc ρf

…… maximum fail setting depth (m) …… recorded valve closing pressure (Pa) …… closing safety margin (Pa) …… control line fluid density (kg/m³)

Source: Well Completion Design Book

Page 69

Chair of Petroleum & Geothermal Energy Recovery

SSSV Example SSSV: Fail close setting depth calculation Calculate the fail close setting depth for a well with hydraulic oil control line fluid (0,87 s.g.), 1,2 s.g. packer fluid, a recorded valve closure pressure of 1500 psi and a recommended safety margin of 200 psi.

Source: Well Completion Design Book

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