Completion Design Course PDF

Preview

Summary

Completion Design Course...

Description

COMPLETION DESIGN

CONTENTS 1.

2.

INTRODUCTION

1-1

1.1 1.2 1.3

DESIGN PROCESS OBJECTIVES FUNCTIONS OF A COMPLETION

1-1 1-5 1-6

RESERVOIR CONSIDERATIONS

2-1

2.1

2.2

2.3

3.

CHARACTERISTICS OF RESERVOIR ROCKS 2.1.1 Porosity 2.1.2 Permeability 2.1.3 Relative Permeability 2.1.4 Wettabilty 2.1.5 Fluid Distribution 2.1.6 Fluid Flow In The Reservoir 2.1.7 Pressure Distribution Around the Wellbore EFFECTS OF RESERVOIR CHARACTERISTICS 2.2.1 Reservoir Drive Mechanisms 2.2.2 Reservoir Homogeneity RESERVOIR/PRODUCTION FORECAST

2-1 2-1 2-1 2-1 2-2 2-2 2-3 2-3 2-4 2-4 2-7 2-9

COMPLETION DESIGN CLASSIFICATION

3-1

3.1 3.2

3-1 3-2 3-2 3-2 3-2 3-4 3-4 3-5 3-7 3-8 3-10 3-10 3-10 3-12 3-13 3-17 3-17 3-18 3-21 3-23 3-23 3-23 3-23 3-23 3-24 3-25

3.3

3.4

3.5

3.6

3.7

INTRODUCTION CLASSIFICATION OF COMPLETIONS 3.2.1 Reservoir/Wellbore Interface 3.2.2 Mode of Production 3.2.3 Number of Zones Completed CLASSIFICATION-BY RESERVOIR/WELLBORE INTERFACE 3.3.1 Open Hole Completions 3.3.2 Uncemented Liner Completions 3.3.3 Perforated Cemented Liner Completions 3.3.4 Perforated Cemented Casing Completions CLASSIFICATION-BY MODE OF PRODUCTION 3.4.1 Tubingless Completions 3.4.2 Tubing Flow Completions 3.4.3 High Rate Liner (or Monobore) 3.4.4 Artificial Lift CLASSIFICATION BY NUMBER OF ZONES COMPLETED 3.5.1 Single Zone Completions 3.5.2 Multiple Zone Completions HORIZONTAL COMPLETIONS 3.6.1 Open Hole 3.6.2 Uncemented Liner 3.6.3 External Casing Packers 3.6.4 Cemented And Perforated Liner 3.6.5 Pre-Packed Screen 3.6.6 Gravel Pack SUBSEA COMPLETIONS

 Tristar T.S.L. 1999 Rev 02

i

COMPLETION DESIGN 3.8

4.

3-25

COMPLETION EQUIPMENT

4-1

4.1

4-3 4-3 4-3 4-4 4-4 4-6 4-9 4-10 4-10 4-12 4-14 4-15 4-15 4-15 4-15 4-16 4-16 4-17 4-17 4-17 4-17 4-17 4-17 4-19 4-19 4-19 4-19 4-19 4-20 4-23 4-25 4-25 4-25 4-25 4-27 4-27 4-27 4-30 4-30 4-33 4-33 4-34 4-34 4-34 4-35 4-37

4.2 4.3 4.4 4.5

4.6

4.7

4.8

4.9 4.10

4.11 4.12

4.13

ii

ANNULUS CONFIGURATIONS

WIRELINE RE-ENTRY GUIDE 4.1.1 Bell Guide 4.1.2 Mule-Shoe Re-entry Guide TUBING PROTECTION JOINT WIRELINE LANDING NIPPLES 4.3.1 Nippleless Lock Systems PERFORATED JOINTS PACKERS 4.5.1 Classification Of Packers 4.5.2 Retrievable Packers 4.5.3 Permanent Packers 4.5.4 Permanent/Retrievable Packers PACKER SETTING METHODS 4.6.1 Mechanical Setting 4.6.2 Electric Wireline Setting 4.6.3 Hydraulic Setting 4.6.4 Setting Adapter Kit RETRIEVABLE PACKER ACCESSORIES 4.7.1 Travel Joint 4.7.2 Adjustable Union 4.7.3 Snap Latch 4.7.4 Safety Joint 4.7.5 Pump-Out Ball And Seat PERMANENT PACKER ACCESSORIES 4.8.1 Locator Tubing Seal Assembly 4.8.2 Seal Bore Extension 4.8.3 Tubing Anchor Seal Nipple 4.8.4 Polished Bore Receptacle (PBR) 4.8.5 Tubing Seal Receptacles SLIDING SIDE DOORS (SSDS) SIDE POCKET MANDRELS 4.10.1 Gas Lift Valves 4.10.2 Dummy Valves 4.10.3 Chemical Injection Valves 4.10.4 Circulating Valves 4.10.5 Differential Dump Kill Valves 4.10.6 Equalising Dummy Valves SUB-SURFACE SAFETY VALVES 4.11.1 Sub-Surface Safety Valve Applications SUB-SURFACE CONTROLLED SUB-SURFACE SAFETY VALVES 4.12.1 Pressure-Differential Safety Valves 4.12.2 Ambient Type Safety Valves 4.12.3 Injection Valves SURFACE CONTROLLED SUB-SURFACE SAFETY VALVES 4.13.1 Wireline Retrievable SCSSV 4.13.2 Tubing Retrievable SCSSV

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN

5.

4.14 SAFETY VALVE LEAK TESTING 4.14.1 API Leakage Limit In Gas Wells 4.14.2 API Leakage Limit In Oil Wells 4.15 FLOW COUPLINGS 4.16 BLAST JOINTS 4.17 ANNULUS SAFETY VALVES 4.18 SURFACE CONTROL MANIFOLDS 4.19 CONTROL LINES 4.20 TUBING 4.21 WELLHEADS 4.22 TUBING HANGER SYSTEMS 4.22.1 Bowl Type Tubing Head/Mandrel Type Tubing Hanger 4.22.2 Ram Type Tubing Head 4.22.3 Multiple Tubing Heads/Hangers 4.23 XMAS TREES 4.23.1 Composite Tree 4.23.2 Solid Block Tree 4.23.3 Spool Tree 4.23.4 Subsea Xmas Tree Systems 4.23.5 Surface Tree Valve Arrangment

4-39 4-39 4-40 4-40 4-40 4-40 4-42 4-43 4-43 4-43 4-45 4-45 4-46 4-49 4-50 4-50 4-50 4-50 4-51 4-51

COMPLETION SELECTION AND DESIGN CRITERIA

5-1

5.1 5.2 5.3 5.4 5.5 5.6 5.7

6.

WELL PARAMETERS WELL LOCATION SAFETY OPERATIONAL FUNCTIONS RESERVOIR MONITORING/LOGGING/MAINTENANCE COMPLETION STRING SERVICING/MAINTENCE EXAMPLE SUBSEA WELL FUNCTIONAL REQUIREMENTS

5-3 5-5 5-5 5-6 5-7 5-8 5-9

TUBING TECHNOLOGY

6-1

6.1 6.2

6-1 6-1 6-1 6-1 6-2 6-3 6-4 6-4 6-4 6-4 6-5 6-5 6-7 6-7 6-7 6-8

6.3 6.4

6.5

DEFINITIONS APPLICATIONS 6.2.1 Casing 6.2.2 Tubing OCTG MARKET FINISHED PRODUCT 6.4.1 Size 6.4.2 Weight 6.4.3 Grade 6.4.4 Connection Type 6.4.5 Range 6.4.6 Example Pipe Designations GRADES OF STEEL 6.5.1 API Grades 6.5.2 Proprietary Grades 6.5.3 Selection of Grades

 Tristar T.S.L. 1999 Rev 02

iii

COMPLETION DESIGN

7.

6.6

CONNECTIONS 6.6.1 Tubular End Forms 6.6.2 Connection Forms 6.6.3 Connection Criteria 6.6.4 Thread Terminology 6.7 PREMIUM CONNECTION DEVELOPMENT 6.8 CONNECTION SEALING METHODS 6.8.1 Metal-to-Metal Seals 6.8.2 Thread and Dope Seals 6.9 THREAD COMPOUNDS 6.9.1 Composition 6.9.2 Sealing 6.9.3 Practical Use 6.9.4 Environmentally Friendly Thread Compounds 6.10 CHROME TUBULARS 6.10.1 The Corrosion Problem 6.10.2 13% or 23% Chrome Steel Solution 6.10.3 Corrosion Resistant Alloy (CRA) Grades 6.10.4 Surface Treatment Of Chrome Threads

6-9 6-9 6-9 6-9 6-10 6-13 6-14 6-14 6-14 6-15 6-15 6-16 6-16 6-17 6-17 6-17 6-17 6-18 6-18

TUBING DESIGN

7-1

7.1 7.2

7-1 7-1 7-1 7-5 7-5 7-5 7-5 7-6 7-6 7-6 7-7 7-7 7-7 7-7 7-8 7-8 7-8 7-10 7-13 7-14 7-15 7-15 7-18 7-19 7-19 7-19 7-20 7-20

7.3

7.4

7.5

7.6 7.7

7.8

iv

THEORY OF TUBING DESIGN PROPERTIES OF STEEL 7.2.1 Mechanical Properties of Steel 7.2.2 Temperature TUBING MOVEMENT/STRESS RELATIONSHIP 7.3.1 Free Movement 7.3.2 Limited Downward Movement 7.3.3 Anchored Tubing REQUIRED WELL DATA 7.4.1 Casing Profile/Geometry 7.4.2 Tubing Data 7.4.3 Bottomhole Pressure 7.4.4 Temperatures (Static and Flowing) 7.4.5 Reservoir Fluids 7.4.6 Completion Fluid PRESSURE INDUCED FORCES 7.5.1 Piston Effect 7.5.2 Buckling Effect 7.5.3 Ballooning Effect TEMPERATURE EFFECT EVALUATION OF TOTAL TUBING MOVEMENT 7.7.1 Anchored Tubing 7.7.2 Tubing Permitting Limited Motion 7.7.3 Packer Setting TUBING LOAD CONDITIONS 7.8.1 Pressure Testing 7.8.2 Acid Stimulation 7.8.3 Fracturing

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN 7.8.4 Flowing 7.8.5 Shut-In 7.8.6 Load Condition Summary 7.9 TUBING SELECTION 7.9.1 Critical Factors 7.9.2 Tubing Size And Weight 7.9.3 Anchoring Systems 7.10 TUBING STRESS CALCULATIONS 7.10.1 Calculation Methods 7.10.2 Safety Factor 7.10.3 External Pressure Limit 7.10.4 Packer Load Limits 7.10.5 Example Manual Calculation

 Tristar T.S.L. 1999 Rev 02

7-22 7-22 7-26 7-26 7-26 7-27 7-28 7-29 7-29 7-31 7-32 7-33 7-34

v

COMPLETION DESIGN

vi

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN 1.

INTRODUCTION

1.1

DESIGN PROCESS The purpose of this course is to provide delegates with a general understanding of the completion design process and its importance on well productivity, well servicing capabilities and completion life. These in consequence, have a large impact on costs and field profit. The approach to completion design must be interdiscipline, involving Reservoir Engineering, Petroleum Engineering, Production Engineering and Drilling Engineering. Many of the decisions made by the various disciplines are interrelated and impact on the decisions made by other disciplines. For instance, the decision on the well architecture may subsequently be changed due to the availability of well servicing or workover techniques. This does not mean that the process is sequential and many decisions can be made from studies and analysis run in parallel. The design process consists of three phases:   

Conceptual Detailed design Procurement.

The activities in each phase are illustrated in Figure 1.1, Figure 1.2 and Figure 1.3. The conceptual design process guides the engineers through analysis and key questions to be considered. During this phase, the user will resolve many of the dilemmas, raised by the interrelated decisions, at an early time. The final conceptual design will be used as the basis for the detailed design process. The conceptual design process begins at the field appraisal stage when a Statement Of Requirements (SOR) of the completion is produced. It is essential that this is an accurate statement including all the foreseen requirements, as it has a fundamental effect on the field final design and development. As more information is gleamed from further development wells and as well conditions change, the statement of requirements need to reviewed and altered to modify the conceptual design for future wells. This provides a system of ongoing completion optimisation to suit changing conditions, increasing knowledge of the field and incorporating new technologies.

 Tristar T.S.L. 1999 Rev 02

1-1

COMPLETION DESIGN

Figure 1.1 - Conceptual Completion Design Process

1-2

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN

Figure 1.2 - Detailed Completion Design Process

 Tristar T.S.L. 1999 Rev 02

1-3

COMPLETION DESIGN

Figure 1.3 - Procurement Process

1-4

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN 1.2

OBJECTIVES The fundamental objectives for a completion are to:    

Achieve a desired (optimum) level of production or injection. Provide adequate maintenance and surveillance programmes. Be as simple as possible to increase reliability. Provide adequate safety in accordance with legislative or company requirements and industry common practices. Be as flexible as possible for future operational changes in well function. In conjunction with other wells, effectively contribute to the whole development plan reservoir plan. Achieve the optimum production rates reliably at the lowest capital and operating costs.

  

These may be summarised as to safely provide maximum long-term profitability. This, however, in reality is not simple and many critical decisions are needed to balance long term and short term cash flow and sometimes compromises are made. An expensive completion may derive more long term profit than a low cost completion but the initial capital costs will be higher (Refer to Figure 1.4 below).

Figure 1.4 – Completion Design Versus Profitability

 Tristar T.S.L. 1999 Rev 02

1-5

COMPLETION DESIGN On the other hand if the data available are not accurate, the estimate of some well performance and characteristics throughout the life of the well may be wrong and early workover or well intervention operations will impact on well profitability. An inherent problem is that the Reservoir Engineering Department’s objectives do not coincide with the Completion Engineering Department’s in that Reservoir Engineering’s objectives are based on the entire field performance, whereas the Completion Group’s is to optimise for profit on a long term well by well basis which includes well servicing and/or workover. Reservoir and geoscience groups often have to set plans and objectives for the field on well performance based on limited information, in the early stages, but are not concerned about production problems, well maintenance or detailed operations.

1.3

FUNCTIONS OF A COMPLETION The main function of a completion is to produce hydrocarbons to surface or deliver injection fluids to formations. This is its primary function, however a completion must also satisfy a great many other functions required for safety, optimising production, servicing, pressure monitoring and reservoir maintenance. These main functional requirements must be built into the conceptual design and include:       

Protecting the production casing from formation pressure. Protecting the casing from corrosion attack by well fluids. Preventing hydrocarbon escape if there is a surface leak. Inhibiting scale or corrosion. Producing single or multiple zones. Perforating (underbalanced or overbalanced). Permanent downhole pressure monitoring.

These functional requirements are addressed during the course presentation and in greater detail in the Section 5 of this manual.

1-6

 Tristar T.S.L. 1999 Rev

COMPLETION DESIGN 2.

RESERVOIR CONSIDERATIONS Oil and gas wells are expensive faucets that enable production of petroleum reservoirs or allow injection of fluids into an oil or gas reservoir. As pointed out in Section 1.1, a completion conceptual design must take into account all the well objectives to produce the optimum design to maximise profitability. The purpose of this section is to consider the characteristics of reservoir fluids and the flow of these in the area around the wellbore to allow these parameters to be tied into the well completion design and well intervention/workover operational requirements.

2.1

CHARACTERISTICS OF RESERVOIR ROCKS

2.1.1

Porosity Porosity or pore space in reservoir rocks provides the container for the accumulation of oil and gas and gives the rock characteristic ability to absorb and hold fluids. Most commercial reservoirs have sandstone, limestone or dolomite rocks, however some reservoirs even occur fractured shale.

2.1.2

Permeability Permeability is a measure of the ability of which fluid can move through the interconnected pore spaces of the rock. Many rocks such as clays, shales, chalk, anhydrite and some highly cemented sandstones are impervious to movement of water, oil or gas even although they may be quite porous. Darcy, a French engineer, working with water filters, developed the first relationship which described the flow through porous rock which is still used today. Darcy’s Law states that the rate of flow through a given rock varies directly with permeability (measure of the continuity of inter-connected pore spaces) and the pressure applied, and varies inversely with the viscosity of the fluid flowing. In a rock having a permeability of 1 Darcy, 1cc of a 1cp viscosity fluid will flow each second through a portion of rock 1cm in length and having a cross-section of 1cm2, if the pressure across the rock is 1 atmosphere.

2.1.3

Relative Permeability As normally two or three fluids exist in the same pore spaces in a reservoir, relative permeability relationships must be considered. Relative permeability represents the ease at which one fluid flows through connecting pore spaces in the presence of other fluids, in comparison to the ease that it would flow if there were no other fluid. To understand this, assume a rock filled with only oil at high pressure where gas has not been able to come out of solution, the following applies:  



 

 Tristar T.S.L. 1999 Rev 02

All the available space is taken up by the oil and only oil is flowing. If reservoir pressure is allowed to decline, some lighter components of the oil will evolve as gas in the pore spaces. Flow of oil is reduced but gas saturation is too small for it to flow through the pores. If pressures to continue to decline, gas saturation continues to increase and at some point (equilibrium gas saturation) gas begins to flow and the oil rate is further reduced. With further increases in gas saturation, the gas rate continues to increase and less oil flows through the pores until finally only gas flows. Significant oil may still occupy the pores but cannot be recovered by primary production means as the permeability to oil has dropped to zero.

2-1

COMPLETION DESIGN This same principle governs the flow of oil in the presence of water. The saturation of each fluid present affects the ease of fluid movement or relative permeability. The gas-oil or water-oil relative permeability relationships of a particular reservoir rock depend on the configurations of the rock pore spaces and the wetting characteristics of the fluids and rock surfaces. In an oil-water system, the relative permeability to oil is significantly greater when the rock is ‘water wet’. 2.1.4

Wettabilty Most reservoirs were formed or laid down in water with oil moving in later from adjacent zones to replace a portion of the water. For this reason, most reservoir rocks are considered to be ‘water wet’. This means that the grains of the rock matrix are coated with a film of water permitting hydrocarbons to fill the centre of the pore spaces. The productivity of oil in this condition is maximised. Although it is extremely difficult to determine wettability of cores due to the cutting and preparing specimens for laboratory testing which alters the wettability characteristics, it is not important as this characteristic is included in the permeability measurements. However, it is important when completing or servicing the well in that any foreign substance which may come into contact with the rock can alter its wettability characteristic, reduce the relative permeability to hydrocarbon fluids and/or cause emulsion which may block flow.

2.1.5

Fluid Distribution The distribution of fluids vertically in the reservoir is very important as the relative amounts of oil, gas and water present at a particular level determines the fluids that are produced by a well completed at that level and also influence the relative rates of fluid production. In rock the capillary forces, which are related to water wettability, act to change the normal sharp interfaces between the fluids separated by density. From the point in a zone of the free water level upward to some point where water saturation becomes constant is called the ‘transition zone’. Relative permeability permits both water and oil to flow within the transition zone. Water saturation above the transition zone is termed ‘irreducible water saturation’ or more commonly the ‘connate water saturation’. Above the transition zone, only oil will flow in an oil-water system. Connate water is related to permeability and pore channels in lower rocks are generally smaller. For a given height, the capillary pressure in two different pore sizes will be the same, therefore the water film between the water and the oil will have the same curvature, hence more oil will be contained in larger pore spaces. The nature and thickness of the transition zones between the water and oil, oil and gas, and water and gas are influenced by several factors: uniformity, permeability, wettability, surface tension and the relative density differences between the fluids. These can be summarised in three statements:   

The lower the permeability of a given sand, the higher will be the connate water saturation. In lower permeability sands, the transition zones will be thicker than in higher permeability sands. Due to the greater density difference between gas and oil as compared to oil and water, the transition zone between the oil and gas is not as thick as the transition zone between oil and water.

A well completed in the transition zone will be expected to produce both oil an...