14. Intro to Completions

Question 1

What are the 3 requirements of a completion?

Answer 1

Safe, Efficient, and Means of oil or gas production

Question 2

What is the purpose of the completion?

Answer 2

Designing Casing protection, tubing string removal, safet or contingency, and production control for means of oil and gas production

Question 3

Factors affecting Well Performance

Answer 3

Estimated Reservoir boundary, measured reservoir properties, controlled completions.

Question 4

Types of well profile

Answer 4

Vertical, deviated, and horizontal

Question 5

Casing vs. Liner

Answer 5

Casing extends between cap rock and reservoir; Liner only extends into reservoir

Question 6

open-hole vs. cased hole

Answer 6

No downhole flow control or isolation, producing formation is unsupported, casing only provides isolation between shallower formations if cemented; cased hole provides more support for production formation

Question 7

List and compare different tubing completion

Answer 7

Casing/liner; tubing/packer/tailpipe provides casing string with more protection from fluid and pressure effects

Question 8

What’s the function of tubing?

Answer 8

Provides the primary conduit from the producing interval to the wellhead production facilities.

Question 9

Tubing String Specifications

Answer 9

Size, material grade, tool joint, construction

Question 10

String Design Factors

Answer 10

Pressure and tension less than 80 percent of tubing yield strength; Production rate; wellbore environment; tubular connectioins and geomentry; forces and stress throughout life of completion

Question 11

Piston Effect

Answer 11

Force up or down on the end of tubing string

Question 12

Buckling Effect

Answer 12

unequal force distribution caused by a large internal tubing pressure differential; only occcurs with high internal tubing pressures and contributes very little to tubing length contraction

Question 13

Ballooning Effect

Answer 13

If tubing collapses an increase in length and compression force on packer; if tubing expands length is shortened and tension on packer; Reverse balloning/collapse tubing causes more effect than Balloning

Question 14

Temperature Effect

Answer 14

Cooling shortens the length of tubing if free to move, if restrained tension applied to packer; When heated the tubing elongates if free to move and if restrained compresses packer

Question 15

What’s a Packer?

Answer 15

Sub-surface tool; provides a seal between Tubing and casing (or Open Hole) of well and preventing the movement of fluids past sealing point; counteract Piston Effect

Question 16

Intervention Reasons to Run Packer

Answer 16

well testing, well repair, stimulation, sand control

Question 17

Production Reasons to Run Packer

Answer 17

to protect casing from corrosive fluids, keep high formation pressures from cassing and wellhead, separate production from different zones, zonal isolation

Question 18

Perforation

Answer 18

Process of creating a clear channel of communication between the wellbore and the reservoir

Question 19

Key parameters of perforation

Answer 19

Perforated interval, shot density, hole size, bottom hole perforating pressure, perforation phasing

Question 20

Overbalanced

Answer 20

BHP in wellbore > reservoir pressure so surge of pressure into reservoir after perforation acts to compact debris; requires less complex equipment and techniques

Question 21

Underbalanced

Answer 21

BHP in wellbore <reservoir pressure so surge of pressure into wellbore removes perforation debris, reduces likelihood of near-wellbore damage, and requires special equipment and techniques

Question 22

Extreme Overbalanced Perforation (EOP)

Answer 22

BHP in wellbore > fracture initiation pressure; formation exposed to wellbore pressure and fluid rushing into perforations generate multiple small fracs that remain open after the operation.

Question 23

Dynamic Underbalanced

Answer 23

PURE, SLB proprietary technique, produces cleanest perforation tunnels and may actually provide slight stimulation (negative S) in some environments

Question 24

Effective perforatitons and Phasing

Answer 24

0 to 180 degrees equals all; 120 degrees equals 2/3; 60 degrees equals 1/3 communication with fracture

Question 25

Phasing criteria

Answer 25

zero degrees cor screenless sand control, 180 degress if oreinted in fracture plane, 60 degrees less initiation pressure and tortuosity; hole size minimum of 6 proppant diameters; generally use 8 to 10 proppant diamters used to offset variations in hole size due to small gun variances and off centered guns

Question 26

Criteria for natural flow in a well

Answer 26

Po< Pwf

Question 27

What does artificial lift do to help production?

Answer 27

increase pressure differential