Page 262 - Drilling Technology in Nontechnical Language

Chapter 10 – EVALUATION 253

The plot of pressure and derivative curves makes it possible to identify
many more reservoir characteristics than was previously possible. Some

examples are shown in figure 10–13, in which the lower curve in each
graph is the derivative, and the top curve is the pressure.

Fig. 10–13. Pressure and derivative curves for different reservoirs
Courtesy of Schlumberger.

Various treatments are available to improve the initial performance of
a well. For instance, acid can be used to etch channels in the rock around
the wellbore, improving the permeability into the well. A transient test
before treatment can be compared with one after treatment to evaluate the
effectiveness of the treatment.

Summary

This chapter showed how data from the well is obtained using various
methods of sampling and measuring. This data is used to monitor and
optimize performance, optimize future drilling activities (well planning
and operations), recognize a commercially viable hydrocarbon reservoir,
and to optimize exploitation of the reservoir.
In particular, the activities encompassed by mud logging, wireline
logging, surface and subsurface sampling, and production well testing
were discussed in some detail. The working principles behind different
types of electric log were described.

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