Page 38 - Introduction to Petroleum Engineering

22 INTRODUCTION

1.5 A. A project is expected to recover 200 million STB of oil. The project will
require installing an infrastructure (e.g., platforms, pipelines, etc.) that costs
$1.2 billion and another $0.8 billion in expenses (e.g., royalties, taxes, operating
costs). Breakeven occurs when revenue = expenses. Neglecting the time value
of money, what price of oil (in $/STB) is needed to achieve breakeven?
b. Suppose a fire on the platform adds another $0.5 billion to project cost.
Neglecting the time value of money, what price of oil (in $/STB) is
needed to achieve breakeven?
1.6 A. The water cut of an oil well that produces 1000 STB oil per day is 25%.
What is the water production rate for the well? Express your answer in STB
water per day.
b. What is the WOR?
1.7 A. Fluid production from a well passes through a separator at the rate of
1200 MSCF gas per day and 1000 STB oil per day. What is the separator
GOR in MSCF/STB?
b. Based on this information, would you classify the fluid as black oil or
volatile oil?
1.8 A. How many acres are in 0.5 mi ?
2
b. If one gas well can drain 160 acres, how many gas wells are needed to
drain 1 mi ?
2
1.9 A. A wellbore has a total depth of 10 000 ft. If it is full of water with a pressure
gradient of 0.433 psia/ft, what is the pressure at the bottom of the wellbore?
b. The pressure in a column of water is 1000 psia at a depth of 2300 ft. What
is the pressure at a shallower depth of 2200 ft.? Assume the pressure gra-
dient of water is 0.433 psia/ft. Express your answer in psia.
1.10 A. Primary recovery from an oil reservoir was 100 MMSTBO where 1
MMSTBO = 1 million STB of oil. A water flood was implemented
following primary recovery. Incremental recovery from the water flood
was 25% of original oil in place (OOIP). Total recovery (primary recovery
plus recovery from water flooding) was 50% of OOIP. How much oil (in
MMSTBO) was recovered by the water flood?
b. What was the OOIP (in MMSTBO)?
1.11 A. A core contains 25% water saturation and 75% oil saturation before it is
flooded. Core floods show that the injection of water into the core leaves
a residual oil saturation of 25%. If the same core is resaturated with oil
and then flooded with carbon dioxide, the residual oil saturation is 10%.
What is the displacement efficiency of the water flood? Assume displace-
)
S
ment efficiency can be estimated as E D S ( oi S / .
oi
or
b. What is the displacement efficiency of the carbon dioxide flood?
1.12 The revenue from gas produced by a well is $6 million per year. The gas drains an
area of 640 acres. Suppose you have 1 acre in the drainage area and are entitled to
25% of the revenue for your fraction of the drainage area, which is 1 acre/640
acres. How much revenue from the gas well is yours? Express your answer in $/yr.