Page 236 - Drilling Technology in Nontechnical Language

10

EVALUATION

Overview

The term evaluation covers several different techniques that together
allow different disciplines within the team (drilling, geology, production,
reservoir engineers, etc.) to understand the subsurface conditions. Typical

information obtained will describe lithology, pore fluids present, wellbore
condition, rock structures (bedding planes and faults), and detailed

reservoir characteristics (static and flowing).
This chapter will describe the different types of technique available
and the type and quality of information possible from each.

Evaluation Techniques

The techniques available can be divided into the following major
categories:
1. Physical sampling at the surface (examining drilled cuttings and

returned drilling fluids)
2. Physical sampling down hole (taking cores of rock or samples of
fluids and recovering them to the surface)

3. Electrical logging (using downhole instruments to measure
physical attributes of the formations, casing, and cement)
4. Production testing (flowing hydrocarbons from the reservoir

while measuring pressure)

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