Introduction(#1)

Petroleum Engineering Department

Course Book Barham S. Mahmood [email protected] 7 September 2019

Course overview 2

 The upstream of the petroleum industry involves itself in the business of oil and gas exploration and production activities.  While the exploration activities find oil and gas reserves, the production activities deliver oil and gas to the downstream of

the industry  The petroleum production is definitely the heart of the petroleum industry.

Course overview cont.. 3

 Petroleum production engineering is that part of petroleum engineering that attempts to maximize oil and gas production in a cost-effective

manner.  To achieve this objective, production engineers need to have a thorough

understanding of the petroleum production systems with which they work.  To perform their job correctly, production engineers should have solid background and sound knowledge about the properties of fluids they produce and working principles of all the major components of producing

wells and surface facilities.

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 Introduction to production technology  Completion design − Introduction − Completion Design Considerations − Bottom-hole Completion Techniques − Selection of Production Conduit − Completion String Facilities − Completion String Components − Factor affecting on well completion designs  Perforating − Introduction − Shaped charges − Effect of formation strength on perforator performance − Perforating fluids − Perforating guns

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 Water and Gas Coning − Introduction to Water and Gas Coning − Coning types − Coning dependency − Solving the coning problem − Oil critical rate empirical correlations − Breakthrough Time in Vertical Well  Skin factor − Introduction − Skin zone pressure drop − Pressure drop due to Formation skin factor (𝑺𝒇𝒎) − Pressure drop due to partial perforation skin factor (𝑺𝒑𝒑) − Pressure drop due to completion configuration skin factor (𝑺𝒄) − Flow efficiency (FE)

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 Helical Buckling in tubing − Introduction − Supplied force − Packers permitting free movement a. Piston effect (Hook’s law) b. Buckling effect c. Ballooning effect − Effect of temperature

 Artificial lift methods − − − − − − −

Introduction The importance of Artificial Lift (AL) for world oil production Selection of AL based on ranking criteria Different Artificial lift methods Describe the gas lift process Identification of application areas/advantages for gas lift well unloading process; gas lift hardware components, gas lift completion design

Course policies 7

 Informal lectures, so please interrupt me if you have questions related to the lecture.  No cell phone is allowed during lecture and exams  Be on time  In addition to the exams, there will be some quizzes during the academic year.  Exams and quizzes are closed book

Grading Scheme: 8

 Midterm exam

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 Final exam

%60 Total: %100

Petroleum Engineering Department “Introduction” Lecture #1

Barham S. Mahmood [email protected] 7 September 2019

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Outline Introduction Role of Production Engineer Time Scale of Involvement Key Areas in Production Technology

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Introduction  Production Technologist is responsible for the production system.  The production system describes the entire production process and includes the following principal components:  The Reservoir  The Wellbore  Production Conduit  Wellhead, Xmas Tree and Flow Lines  Treatment Facilities

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Elements of the production technology system

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Role of Production Engineer Achieving optimum performance from the production system and To achieve this the technologist must understand:  chemical and physical characteristics of the fluids and,  systems which will be utilised to control the efficient and safe production/injection of fluids

The importance of the production chemistry input has only recently been widely acknowledged.

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 The main disciplines which are involved in Production Technology are: 1) Production Engineering:  Fluid flow  Reservoir dynamics

 Equipment design, installation, operation and fault diagnosis

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2) Production Chemistry:  The fluids - produced, injected and treatment fluids  The rock - mineralogy, physical/chemical properties and rock strength and response to fluid flow.

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Time Scale of Involvement  The production technologist is involved in the initial well design and will have interests in the drilling operation from the time that the reservoir is penetrated.  In other words,the production technologist will contribute to company operations on a well from initial planning to abandonment.  The inputs in chronological order to the development and the operation of the well are listed below:

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Drilling  Casing string design  Drilling fluid selection

Completion  Design/installation of completion string

Production  Monitoring well and completion performance

Workover/Re-completion  Diagnosis/recommendation/ installation of new or improved production systems

Abandonment  Identify candidates and procedures

Production Engineers

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Key Areas in Production Technology Production technology is both a diverse and complex area. It is, possible to identify several key subject areas:  Well Productivity  Well Completion  Well Stimulation  Associated Production Problems  Remedial and Workover Techniques  Artificial Lift / Productivity Enhancement  Surface Processing

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Production Technology Topics Well Performance

Production enhancement/ artificial lift

Production problems

Well Completion

Production Technology

Well monitoring diagnosis and workover

Surface Processing

Stimulation and remedial processes

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 Well Productivity  The productivity of the system is dependent on the pressure loss which occurs in: – – – – – –

The reservoir The wellbore The tubing string The choke The flow line The separator

 In natural flow conditions:

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Production System –Pressure lose

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Source of pressure loss in a production system

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 Productivity from the production system depends primarily on the pressure loss in the system (from reservoir to separator)  During the production using reservoir natural enrgy

PR = DPSystem + Psep  Where pressure loss occur in different areas; reservoir, well, tubing, chock, valves .. etc

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 The pressure drop which occurs across the reservoir, DPres, is defined as the inflow performance relationship or IPR.  The pressure drop in lifting the fluids from the reservoir to the surface, DPTBG, is known as the vertical lift performance or VLP, or the tubing performance relationship or TPR

PR – PTH = DPRES + DPTH Where; PTH = Tubing head pressure

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 Well Completion  Major part of production technology is concerned with the engineering and installation of completion equipment.

 Completion string is a critical component of the production system and it must be efficiently designed, installed and maintained.  Actual capital costs of the completion string has become a significant proportion of the total well cost.

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 The completion process can be split into several key areas: – The fluids which will be used to fill the wellbore during the completion process.

– The completion must consider and specify how the fluids will enter the wellbore from the formation (open hole, cased hole, etc.). – The design of the completion string itself (safety and minimal pressure loss). – Contingencies are available in the event of changing fluid production characteristics and minor servicing operations.

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 Well Stimulation Why well stimulation is required?  Productivity of a well naturally arises fluids mobility and the flow properties of the rock.  In some cases the degree of inter-connection of the pore space may be very poor.  In such situations it may be beneficial to stimulate the production capacity of the well.

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What are the objectives in stimulation?  Stimulation techniques are intended to: – Improve the degree of inter-connection between the pore space, particularly for low permeability or vugular rocks – Remove or bypass impediments to flow, e.g.. damage. – Provide a large conductive hydraulic channel which will allow the wellbore to communicate with a larger area of the reservoir.

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What are the techniques in stimulation?  In general, there are four principal techniques applied, namely: – Propped Hydraulic Fracturing

– Matrix Acidisation – Acid Fracturing

– Frac Packing

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Propped Hydraulic Fracturing  Whereby fluids are injected at a high rate and at a pressure which exceeds the formation break down gradient of the formation.  The rock will then fail mechanically producing a “crack”.  To prevent closure or healing of the fracture, it is propped open by a granular material.  This technique increases the effective well bore radius of the well.

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Matrix Acidisation This process is conducted at pressures below the formation break down gradient.

It requires the injection of acid into the reservoir to either dissolve the rock matrix and/or dissolve damage material contaminants which has invaded the rock pore space. The main objective of acidisation is to increase the conductivity of the rock.

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Acid Fracturing Whereby acid injected at a pressure above the formation breakdown gradient, creates a fracture. The acid then etches flow channels on the surface of the fracture which on closure will provide deep conductive flow channels.

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Frac Packing Which is a shallow penetrating hydraulic fracture propagated usually into a formation of moderate to high permeability, and is subsequently propped open prior to closure. The process is used to reduce the near wellbore flow induced stress, and in some cases can also limit/reduce sand production

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 Associated Production Problems Problems are frequently encountered as a results of:  Physico-chemical changes − The produced fluids experience a temperature and pressure reduction and deposition of heavy hydrocarbon materials such as asphaltenes and waxes. − Incompatibility between reservoir fluids and those introduced into the wellbore which may result in formation damage, e. g., scale deposits or emulsions.

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− The mechanical collapse or breakdown of the formation may give rise to sand production.

− Siliceous or clay fines may be produced creating plugging in the reservoir and wellbore. − Corrosion due to the inherent corrosive nature of some of the components contained in the hydrocarbon system, for example, hydrogen sulphide (H2S), carbon dioxide (CO2 ), etc. chloride ions in produced water and oxygen in injected water can also create corrosion. − Processing problems associated radioactive scales, foams, heavy metals deposits, etc.

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 Remedial and Workover Techniques  The production technologist is responsible for monitoring and ensuring the ongoing safe operation of the well.  As such the responsibilities include:

1) Identification of problems and their source 2) Plan the required corrective action

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1) Identification of problems and their source  This is normally conducted on the basis of surface information which indicates changes in production characteristics such as rate and pressures.  In addition downhole investigations using production logging techniques and transient pressure surveys (flow tests) can also help to identify the location of problems and the reasons for the changes.

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2) Plan the required corrective action  This requires considerable attention to detail and will necessitate: − Identifying the equipment, manpower and other capabilities required. − Identification and assessment of the unknowns/uncertainties. − Identification and evaluation of the key safety points and milestones. − The assessment of the probability of technical and economic success. − Attention to detail and careful workover planning.

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 Artificial Lift It may be necessary to assist in the lift process by either:  Reducing flowing pressure gradients in the tubing e.g. reducing the hydrostatic head by injecting gas into the stream of produced fluids. This process is known as gas lift. − This will result in change in fluid composition in the tubing above the point of injection.  Providing additional power using a pump, to provide the energy to provide part or all of the pressure loss which will occur in the tubing.

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 When pumps are used, apart from fluid recompression (and heating) and the associated fluid properties, there is no change in fluid composition.  There are specific mechanisms for providing pump power and the lift mechanism. e.g. 1) Electrical powered centrifugal pumps

2) Hydraulic powered centrifugal/turbine, jet and reciprocating pumps 3) Sucker rod and screw pumps 4) Gas lift

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 Each artificial lift system has a preferred operating and economic envelope influenced by factors such as: − Fluid gravity

− G.O.R. − Production rate

− Sand production − Devlopment factors such as well type, location and

availability of power/gas.

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 Surface Processing The objectives of surface processing are as follows:  To effectively separate oil, gas, water and remove other produced materials such as sand.

 To monitor and adjust the chemical properties prior to separation/transport/reinjection, e.g.: − Defoaming − Filtration − Scale Inhibition

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 To dispose of the oil and gas via pipeline or to storage − this will necessitate equipment for pumping, compression, water removal, hydrate suppression and pour point depression.

 To prepare for and to reinject necessary fluids such as gas and water.

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