Page 4 - Treating Oilfield Emulsions

Segment I
Chapter 1

The Treating Problem
Petroleum Extension-The University of Texas at Austin
A t some time in the life of almost every oilwell, the reservoir (B, C), may produce clean oil at the
fi more water is produced with the crude oil beginning. Figure 2 shows the same reservoir
than is acceptable to the pipeline company or later in the life of the field. Note the relationship
other carriers. Some wells may produce water atthis laterdatebetween theposition of each well
from the beginning, but, more often, water en­ and what each is producing.
croachment comes later in the life of the field. Figure 3 illustrates another possible cause of
Figure 1 shows, in simplified form, one source of water in oilwells. Casing failure coupled with a
water produced with oil. Both oil and water are poor cementing job at a point above the produc­
contained in the pores of the rock that makes up ing zone allows water to enter the well and con­
the reservoir. In figure 1,a large quantity of water taminate production. To correct the problem, the
liesunderthe oil. Early inthe life ofthe field, some casing can be patched and a squeeze cementing
of the wells that are drilled near the point of oil­ job can be performed, ora packer can be placed in
water contact (A) produce excessive amounts of the tubing-casing annulus to form a temporary
water. Other wells, which are drilled higher on seal above the oil zone and exclude the water.

A

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Figure 1. Sketch showing relative position of oil and water in early life of reservoir. Well A requires plugging
back. Wells Band C produce clean oil.

Figure 2. Same reservoir as in figure 1, portraying later conditions in life of field. Well A is completely watered
out. Well B produces water and cut oil. Well C continues to produce clean oil.

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