Page 18 - A Primer of Oilwell Service and Workover Completion

ADDITIONAL RECOVERY TECHNIQUES 



Petroleum Extension-The University of Texas at Austin

ADDITIONAL RECOVERY TECHNIQUES

fter a well has used up the WATERFLOODING toward other wells in the same res-
A reservoir’s natural drives ervoir. These producing wells then
When the wells drilled into one
and all the hydrocarbons pos- pump up the oil and water, often
sible have been lifted by pumps reservoir stop flowing, the com- by means of a beam pumping
pany representative may hire a
or gas lift, statistics show that unit. Several injection wells sur-
workover contractor to pump,
 to  percent of the oil in round each producing well. This
or inject, water into some of
the reservoir may remain there. procedure is called waterflooding.
them (fig. .). The wells into
This amount of oil can be worth Sometimes a crew injects a
which water is pumped become
recovering if prices are high gas, such as natural gas, nitrogen,
injection wells. This water kills
enough. The petro leum industry or flue gas, in alternating steps
the wells and then sweeps into
has developed several techniques with water to improve recovery. In
the reservoir and moves some of
to produce at least part of this this case it is called gas injection.
the oil that remains in the rock
remaining oil.
One thing to keep in mind
about additional recovery tech-
niques is that they are expensive PRODUCING
and risky. They require special WELL INJECTION
WELLS
chemicals, equipment, and per-
sonnel. And there are no guaran-
tees that a project will work. Of
course, the potential rewards are
high if a project does work out,
but the risk is also high. In most
cases, it takes years before a com-
pany actually starts recovering
any oil from a project. Recover-
ing oil from reservoirs beyond
OIL
the initial production remains
one of the great challenges facing
the oil industry.

Figure .. In waterflooding, water is injected into wells around the
producing well. This is a five-spot pattern—four injection wells and one
producer—but many other patterns can be used.