Page 183 - Petroleum Production Engineering, A Computer-Assisted Approach

Guo, Boyun / Computer Assited Petroleum Production Engg 0750682701_chap12 Final Proof page 179 4.1.2007 2:43pm Compositor Name: SJoearun

SUCKER ROD PUMPING 12/179
28,000

24,000
(a)
20,000
(b)
16,000
Load (lb) 12,000 (c)

8,000

4,000
(d)
0

−4,000
8 7 6 5 4 3 2 1 0 −1 −2 −3 −4
Displacement (ft)
Figure 12.13 Surface to down hole cards derived from surface dynamometer card.

the dynagraph card at the plunger itself. This card indicates 12.3 Use your knowledge of kinematics to prove that for
gross pump stroke of 7.1 ft, a net liquid stroke of 4.6 ft, and Class I lever systems,
afluid load of W f ¼ 3,200 lb. The shape of the pump card, a. the polished rod will travel faster in down stroke
Fig. 12.13d, indicates some down-hole gas compression. than in upstroke if the distance between crank-
The shape also indicates that the tubing anchor is holding shaft and the center of Sampson post is less than
properly. A liquid displacement rate of 200 bbl/day is cal- dimension d 1 .
culated and, compared to the surface measured production b. the polished rod will travel faster in up stroke than
of 184 bbl/day, indicated no serious tubing flowing leak. in down stroke if the distance between crankshaft
The negative in Fig. 12.13d is the buoyancy of the rod
string. and the center of Sampson post is greater than
The information derived from the dynamometer card dimension d 1 .
(dynagraph) can be used for evaluation of pump perfor- 12.4 Derive a formula for calculating the effective di-
mance and troubleshooting of pumping systems. This sub- ameter of a tapered rod string.
ject is thoroughly addressed by Brown (1980).\ 12.5 Derive formulas for calculating length fractions of
equal-top-rod-stress tapered rod strings for (a) two-
sized rod strings, (b) three-sized rod strings, and
Summary (c) four-sized rod strings. Plot size fractions for
This chapter presents the principles of sucker rod pumping each case as a function of plunger area. 5 1
systems and illustrates a procedure for selecting components 12.6 A tapered rod string consists of sections of ⁄ 8 - and ⁄ 2 -
of rod pumping systems. Major tasks include calculations of in. rods and a 2-in. plunger. Use the formulas from
polished rod load, peak torque, stresses in the rod string, Problem 12.5 to calculate length fraction of each size
pump deliverability, and counterweight placement. Opti- of rod. 3 5
mization of existing pumping systems is left to Chapter 18. 12.7 A tapered rod string consists of sections of ⁄ 4 -, ⁄ 8 -,
3
1
and ⁄ 2 -in. rods and a 1 ⁄ 4 -in. plunger. Use the for-
mulas from Problem 12.5 to calculate length fraction
of each size of rod.
References
12.8 The following geometry dimensions are for the
brown, k.e. The Technology of Artificial Lift Methods, pumping unit C–80D–133–48:
Vol. 2a. Tulsa, OK: Petroleum Publishing Co., 1980. d 1 ¼ 64 in.
coberly, c.j. Problems in modern deep-well pumping. Oil d 2 ¼ 64 in.
Gas J. May 12, 1938. c ¼ 24 in.
golan, m. and whitson, c.h. Well Performance, 2nd edi- h ¼ 74.5 in.
3
tion. Englewood Cliffs: Prentice Hall, 1991. Can this unit be used with a 2-in. plunger and ⁄ 4 -in.
nind, t.e.w. Principles of Oil Well Production. New York: rods to lift 30 8API gravity crude (formation volume
McGraw-Hill Book Co., New York, 1964. factor 1.25 rb/stb) at depth of 2,000 ft? If yes, what is
the required counter-balance load?
12.9 The following geometry dimensions are for the
Problems pumping unit C–320D–256–120:
d 1 ¼ 111:07 in.
12.1 If the dimensions d 1 , d 2 , and c take the same values d 2 ¼ 155 in.
for both conventional unit (Class I lever system) and c ¼ 42 in.
air-balanced unit (Class III lever system), how differ- h ¼ 132 in.
ent will their polished rod strokes length be?
1
3
12.2 What are the advantages of the Lufkin Mark II and Can this unit be used with a 2 ⁄ 2 -in. plunger and ⁄ 4 -,
air-balanced units in comparison with conventional 7 ⁄ 8 -, 1-in. tapered rod string to lift 22 8API gravity
units? crude (formation volume factor 1.22 rb/stb) at a