Page 172 - Introduction to Petroleum Engineering

ACTIVITIES 159
8.5.3 exercises

8.1 A. Suppose a pipe string weighs 15 lbf/ft of length. If the pipe is used to form
a string of pipe that is 10 000 ft long, what is the weight of the pipe string?
B. Suppose a pipe string is 10 000 ft long. 6000 ft of the pipe string is made
of pipe that weighs 15 lbf/ft of length. 4000 ft of the pipe string weighs
18 lbf/ft of length. What is the weight of the pipe string?
8.2 A. What volume of mud is needed to fill a section of pipe with inner diameter
.
ID = 45 in. and length = 30 ft? Express your answer in ft and gal.
3
B. Calculate the volume in the annulus between a section of pipe with outer
diameter OD = 7 in., length L = 1200 ft, and the casing with inner diam-
eter = 10 in. Express your answer in ft .
3
8.3 The KB (kelly bushing) is 30 ft above the ground. A well is drilled to a total vertical
depth of 6000 ft below the ground. How many joints of pipe are needed to reach
from the KB to the bottom of the wellbore? Assume each joint of pipe is 30 ft long.
8.4 A. The top of a reservoir is at a depth of 4000 ft SS (SS = subsea or below sea
level). The KB on the drilling rig is 5280 ft above sea level. What is the depth
to the top of the reservoir relative to the KB? Express your answer in ft.
B. Estimate confining pressure p at the depth in Part A using an overburden
con
pressure gradient of 0.43 psia/ft. Express your answer in psia.
8.5 We want to drill a well with a total length of 4000 ft. We know from previous
experience in the area that the drill bit will be effective for 36 hr before it has to
be replaced. The average drill bit will penetrate 20 ft of rock in the area for each
hour of drilling. We expect the average trip to replace the drill bit to take about
8 hr. A trip is the act of withdrawing the drill pipe, replacing the drill bit, and
then returning the new drill bit to the bottom of the hole. Given this information,
estimate how long it will take to drill the 4000 ft. Hint: prepare a table as follows:

Incremental Incremental Cumulative Cumulative
Time (hr) Length (ft) Time (hr) Length (ft)

8.6 Consider the following types of pipe: conductor pipe, surface casing,
intermediate casing, production casing, and production pipe. Which string is
cemented last?

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8.7 If a gas well can drain 160 acres, how many gas wells are needed to drain 3 mi ?
8.8 Bend radius is the distance required for a string of pipe to make a 90° turn.
Suppose the trajectory of a horizontal well requires a quarter of a mile to go
from the kickoff point at the end of the vertical segment of the trajectory to the
beginning of the horizontal segment. How many joints of pipe are needed to
establish the curvature from the vertical segment to the horizontal segment if
each joint of pipe is 30 ft long?