Page 45 - Drilling Technology in Nontechnical Language

36 Drilling Technology in Nontechnical Language Second Edition

1. Prove that oil and gas both exist in the reservoir, obtain
samples of each for analysis, and measure the fluid pressures in

the reservoir.
2. Determine the depths of the gas-oil and oil-water contacts.
3. Take samples of rock in the oil part of the reservoir.
4. Test the oil layer to measure the following:

a. The maximum rate at which the oil can flow before sand
starts to be produced.
b. The maximum possible production rate.

c. Internal reservoir characteristics, such as permeability,
porosity, internal boundaries, pressures, and temperatures.
d. Damage to the reservoir from the drilling operation. This
is known as the mechanical skin and causes a reduction
in permeability.
Now a well proposal document has to be written, which is a request
from the exploration department for a well to be drilled. It provides the
necessary information to the drilling department to start designing for
the well.

Well proposal contents

Well proposal contents include the following information:
1. Type of well (exploration) and well objectives (as stated above).
2. Essential well design data:

a. Surface (rig) location to use, if known.
b. Downhole targets to hit; position, depth, and the acceptable
margin for error.
c. Depths and descriptions of the downhole rock strata, as far as
can be determined.
d. Expected strengths of formations down hole and pressures of

fluids inside the rocks.

e. Temperature profile; how the temperature varies with depth.
f. What information is required from the well.

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