Casing design

Complete Casing Design with types of casing, casing properties, casing functions, design criteria and properties used for designing and one numerical problem

1. Casing Design Lecturer Syed Nawaz Free Lance NDT Inspector Founder of Petroleum Universe

2. Introduction Functions of Casing Casing Types Approach to Casin g Design Numerical Zone Conclusion References Content

3. Hussain.et.al in Fundamentals of Sustainable Drilling says that if a tubular is less 4.5 inch of diameter then it is tubing. The range of casing diameter is 4.5” to 36 ” Once the section of subsurface is drilled, it has to be cased with steel pipe, which is said to be Casing The reason behind the circular shape of casing is even distribution of pressure Casing constitute 20-30% of the total cost of the well. Introduction

4. Casing is installed to prevent the following problems: Faults High pressure formations Toxic materials Thief zones, etc When and Why Casing?

5. To protect near surface unconsolidated formations Provide protection against shallow gas flows Seal off shallow water zones Prevent caving of weak formations Provide protection against shallow blowouts It will ensure that formations at the casing shoe will not fracture at the high hydrostatic pressure which may encountered at later stage. Is usually set in the transition zone below or above an over-pressured zone To seal off a severe loss zone To isolate producing zones, To provide reservoir fluid control To permit selective production in multizone production To isolate lost circulation or abnormally pressured zone Functions of Casing

6. It prevents cross channeling between two or more subsurface fluid bearing layers To provide structural support for the wellhead and BOPs Note: Casing, Tubing, Drill Pipe must all confirm to API series 5 “Tubular Goods” including API Spec, ISO Specifications, etc Why Casing?

7. Stove Casing Conductor Casing Surface Casing Intermediate Casing Production Casing Liner Casing Casing types based on depths and diameters

8. These are marine conductor or foundation pile for offshore drilling It is run to prevent washout of near surface unconsolidated formations, to provide a circulation system This pipe does not carry any weight from the wellhead equipment and can be driven into the ground or seabed The normal size for a stove pipe ranges from 26 in to 42 in Stove Casing

9. Largest diameter Protect near surface unconsolidated formations, seal off shallow water zones Size vary from 16 inch to 48 inch Conductor pipe is always cemented up-to the surface. Conductor Casing

10. Prevent caving of weak formations at shallow depths Shallow blowouts Depth of surface casing depends on aquifers and well head pressure Diameter range is 18.625 to 20 inch in North Sea Operations and casing size in middle east is usually 13.375 Surface Casing

11. Usually set in the transition zone below or above an over-pressured zone Mainly design to overcome the problems like caving shale, thief zones, mobile salt zones It ranges from 7.625 to 13.375 but no specific range of length Intermediate Casing

12. Last casing placed at the top of pay zone. Isolate producing zone Range is of 4.5, 5, 7 inches in O.D Production Casing

13. Do not reach the surface Mounted on liner hangers installed to previous casing string (Intermediate Casing). In liner completions both the liner and the intermediate casing act as the production string. The design criteria for liner is usually the ability to withstand the maximum expected collapse pressure Liners

14. Types of Liner

15. Design process Selection of Casing Sizes Selection of setting depths Definition of design properties Design properties Collapse pressure Burst pressure Yield strength: tensile and compressive Biaxial loading consideration Effect of Bending Design procedure Collapse pressure calculation Burst pressure calculation Tensile/ compressive strength calculation Safety factor Approach to Casing Design

16. Casing depth Selection

17. Collapse Minimum external pressure required for pipe collapse (no internal pressure or loads) Design Properties

18. Based on diameters and thickness there are 4 different types of collapse pressure The API bulletin 5C3 3 reports four formulas for calculating the collapse resistance of tubular goods and they are as follows: Elastic Collapse Pressure Transition Collapse Pressure Plastic Collapse Pressure Yield Strength Collapse Pressure Collapse pressure estimation

19. Yield Strength (x<15.545) Plastic (15.545 < x < 26.025) Transition (26.025 < x < 39.9) Elastic (x > 39.912) Formulas and limitation

20. Under field conditions, a given casing section will be under the combined action of external and internal pressure and axial load due to its own weight Collapse pressure with Axial stress

21. Burst Minimum internal pressure at which pipe permanently deformed (pipe is to no or less external pressure or axial loads) API Burst is given as Lame equation is also used for burst pressure Wall-thickness correction factor 0.875 for standard API tubulars when a 12.5% wall-thickness tolerance is specified.

22. Graphical Design

23. The ability of a metal to tolerate gradual progressive force without any permanent damage or deformation. Classified into 2 pressures or loading: Axial Load and Compressive Load Applying force on a structure directly along the structure axis Yield Strength

24. Axial Load

25. API Design Factors Safety Factor Forces Range (Globally used ) Collapse 1.0-1.125 (1.125) Tension 1.0-2.0 (1.8) Burst 1.0-1.33 (1.1) Triaxial 1.25

26. Casing Size Connections Weight Grade Length Properties of Casing

27. The OD is recognized as the size of Casing. The size of casing vary from 4.5” to 36” Drift Diameter: allowable diameter for next coming tool Breaking out the sequence then factors are to be estimated such as Connections Mud weight Cementing Dogleg severity Outside Diameter (OD)

28. Pipe weight is usually expressed as weight per unit length in lb/ft. Weight Weight Outer dia Inner dia Wall thickness Drift dia lb/ft in in in in 53.5= 1658 9.625 8.535 0.545 8.379 47= 1457 9.625 8.681 0.472 8.525 43.5 = 1348 9.625 8.755 0.435 8.599 40 = 1240 9.625 8.835 0.395 8.679 31

29. The steel grade of the casing relates to the tensile strength of the steel from which the casing is made Grade is a dependent property (Chemical Composition, Mechanical Properties) The steel grade is expressed as a code which consists of a letter and a number Grade

30. API Casing length ranges Most commonly used are R-2 Length Ranges Ranges of Length (ft) Average Length (ft) R-1 16-25 22 R-2 25-34 31 R-3 >34 42

31. Casing Specifications

32. API provides 4 types of Casing connectors: CSG short round threads and couplings LCSG long round threads and couplings BCSG buttress threads and couplings XCSG extreme line threads CSG and LCSG combined are called API 8-Round threads Casing connections

33. An intermediate section of 17.5 size was planned to be drilled at a depth of 14,000 ft . A 13 3/8 OD casing is to be set and cemented in this section. There are four casing types available in stocks which are shown in Table below. Maximum burst pressure has to be assumed when casing is full of 15.8 ppg cement slurry and fluid in the annulus is water. In addition, maximum collapse pressure has to be assumed when casing is full of fresh water and annulus is full of 15.8 ppg cement slurry. Safety factor for burst and collapse was designed to be 1.18 and 1.15 respectively . Design a casing that should be used in this section. Numerical Zone

34. Depth of the casing shoe = 14,000 ft Density of cement slurry 15.8 ppg Density of fresh water = 8.34 ppg Collapse safety factor = 1.15 Burst safety factor = 1.18 Given Data

35. Estimate the collapse and burst pressure for the available casing sizes along with safety factor Then estimate collapse and burst pressure of required depth without safety factor Based on magnitude select the casing Procedure

36. Estimating Collapse pressure with the help of outer, inner diameter and yield strength Estimating collapse pressure and burst pressure with reference to depth Formula

37. For ID 12.031 inch Calculating Burst and Collapse of Casing w.r.t to d/t ratio

38. Calculated values

39. = 0.052 X 14000 X (15.8 – 8.34) = 5430.88 psi = 0.052 X 14000 X (15.8 – 8.34) = 5430.88 psi Collapse and Burst Pressure

40. The collapse pressure with safety factor is 5740 and burst pressure is 5961 and the calculated magnitude is 5430.88 which lies between the above values. Thus 12.031 inch ID casing is best. Numerical Conclusion

41. Hussain Rabia “Well Engineering and Construction” Hussain Rabia “Oil Well Drilling Engineering Principles and Practice” Hussain and Majid “Fundamental of Sustainable Drilling” “Formulas and Calculations for Drilling Operations” by G.James “Formulas and Calculations for Drilling, Production and Workover ” by Lapeyrouse Working Guide to Drilling Equipments and Operations by Williams Lyons Drilling Engineering Workbook by Baker Hughes “Drilling Engineering Technology” by Nediljka Gaurina Medimurec University of Zagreb Advanced Oil Well Drilling Engineering by Mitchell Petroleum Well Construction Directional Drilling by Halliburton Adam.et.al “Applied Drilling Engineering” Drilling Engineering A complete well planning Aprroach by Neal Adam Petroleum Engineering Handbook by Warner Jr. Practical Field Reports I can’t mentioned their names References

42. Thank you https://bit.ly/3ibtqZt https://www.facebook.com/Petroleum-Universe-575251903155462/?modal=admin_todo_tour https://www.linkedin.com/company/67110978/admin/ https://www.slideshare.net/SYEDNAWAZ4/edit_my_uploads