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This exploration borehole will be designed and drilled to the
greatest depth of practical interest, and the geological results-the
stratigraphy, ages of the rocks, dips, sonic velocity
characteristics, maturation levels of organic matter in the rocks,
and fossils recovered in cores and samples-all contribute to a
refinement of the original model that was based on the seismic
surveys. More seismic work may be done. If petroleum is not
found, the information gained may lead to the drilling of further
exploratory wells in the area. If petroleum is found, it will be
tested and analyzed, and the pressures and flow rates will be
measured.

TEXT №4.

1. Read the text.
2. Find the key sentence in each paragraph and translate it into
Ukrainian.

The nature of an oil field with a single large pool is quite
different from one with many pools and from one with many
pools in a faulted structure, and the economics also differ. A
single large pool may be developed with relatively few wells
spaced several kilometers apart if the field permeability is good,
or a few wells if the oil column is thick and the field area
relatively small, whereas the same volume of oil in several
faulted reservoirs may require wells for multiple completion on
more than one reservoir (dual completions, even triple
completions). It is in the nature of oil fields that those in
transgressive sequences tend to be large single-pool
accumulations and those in regressive sequences tend to be
multiple-pool accumulations.
The extraction of oil fields tends to result in a gradual
pressure decline in the reservoirs. This not only impairs the
productivity of the field but also leads to surface subsidence
through the compaction of the depleted reservoirs and, in some
fields, the movement of oil or water from undepleted reservoirs
to depleted reservoirs in juxtaposition across faults. Pressure-
maintenance schemes are planned and put into operation early in
the life of a field, usually involving the injection of water at the