Casing Design: 2021 #23

Design 7 in. production casing to be set in 11 lbm/gal mud in a vertical 15,000 ft well. Assume 10 lbm/gal pore pressure. Use three sections (minimum 2,000 ft each) based on pipe body performance properties. Design limits: 90M lbf overpull over buoyed casing weight...[see text]. What is the most cost-effective casing to use in the bottom of the hole?

A) 32 lbf, C-95
B) 29.0 lbf, C-110
C) 29.0 lbf, C-95
D) 26.0 lbf, C-95

Make sure you stay organized on this problem! Build a table of the needed information (provided in the problem or in the Reference on P41 and P67). Get be familiar with how the provided reference is organized; there is tons of data in a very small space and you need to be able to find and use it rapidly. Most importantly, the fomat is not overly similar to what you may be used to using. So here's our table:

Collapse (1.1) Burst (1.1) Tension (1.8).
23.0 lbf, C-95 3764 (4140) 6845 (7530) 486 (632).
26.0 lbf, C-95 5345 (5880) 7818 (8600) 552 (717).
29.0 lbf, C-95 7118 (7830) 8809 (9690) 618 (803).
32.0 lbf, C-95 8864 (9750) 9782 (10760) 681 (885).
29.0 lbf, C-110 7755 (8530) 10200 (11220) 715 (929).
Burst@surface=7780 psi.

Burst@TD: 7780+0.052*9*15000-0.052*10*15000=7000 psi.
Collapse surface=0 psi; Collapse@TD: 0.052*10*14000=7800 psi.
Neutral-Plane-BF=1-MW/65(P41)=1-11/65=0.846*15,000=12462’-NP-collapse-derate-above.
Section-1: TD-collapse-options>7800-is-8864 32 lbf, C-95, “A”.

References: (TS12 P430; GB 11 DCA 1; RG P41, P67).

This is a fairly tough problem. Remember, it's highly unlikely the design will be too complex, and your trick is to find the limiting factor as quickly as possible.

 

DCA: 2021 #22

True statements about decline curve analysis (DCA) include (select any that apply):
__ DCA is the most widely used method of forecasting future production from gas fields.
__ DCA is the most widely used method of forecasting future production from oil fields.
__ All real wells have hyperbolic decline.
__ DCA has few fundamental theoretical foundations.
__ Harmonic decline is a particular case of hyperbolic decline.
__ Exponential decline is a particular case of hyperbolic decline.
__ Hyperbolic decline is a particular case of exponential decline.
__ Hyperbolic decline is a particular case of harmonic decline.
__ Harmonic decline is a particular case of exponential decline.

Of course the provided Reference Guide will offer no assistance on word problems; you must know the material from prior experience or study. Feel free to ask questions in the comment box below.

 X DCA is the most widely used method of forecasting future production from gas fields (TS8 P170).
 X DCA is the most widely used method of forecasting future production from oil fields (TS8 P170).
 X All real wells have hyperbolic decline (TS8 P172).
 X DCA has few fundamental theoretical foundations (TS8 P172).
 X Harmonic decline is a particular case of hyperbolic decline (TS8 P172).
 X Exponential decline is a particular case of hyperbolic decline (TS8 P172).
__ Hyperbolic decline is not a particular case of exponential decline (TS8 P172).
__ Hyperbolic decline is not a particular case of harmonic decline (TS8 P172).
__ Harmonic decline is not a particular case of exponential decline. (TS8 P172).