The Use of Drill
Cuttings in Reservoir Evaluation
By
D.B. Schafer (BP Exploration (Alaska) Inc.) and G. Bolger (PetroTech Associates)
The use of drill
cuttings has been significantly elevated in its importance relative to reservoir
evaluation. In the past,
drill
cuttings commonly have been used to provide
simple and qualitative information about the rock types present and not to make
concrete decisions about the economic viability of any reservoir. However, the
capability exists to perform more advanced reservoir evaluation from the
cuttings as it relates to reservoir properties, performance and predictions. An
additional caveat is that the cost of obtaining the rock material (conventional
cores, sidewall cores) has been eliminated, hence reducing the cost of any well
as much as 10–15%. This translates into approximately $350,000 in cost savings
per North Slope well in Alaska.
Based on the type of drill
bit used, the quality and
quantity of
drill
cuttings can vary. Once
drill
cuttings are collected and
washed they are then ‘picked’ to separate formation representative aggregates
from drilling mud and other contaminants. Advanced rock studies, including Thin
Section Petrography, X-ray Diffraction, Scanning Electron Microscopy, and
Mercury Injection Capillary Pressure can then be performed on the cuttings,
yielding high quality results. Using
drill
cuttings in formation evaluation has
opened up an integral avenue of data collection achieved through significant
cost savings. The data obtained from this technique is invaluable for making
‘setting pipe’ decisions, improving completion practices and many other aspects
regarding how the reservoir should be developed. Here lies yet another very cost
effective tool for oil and gas teams to further their understanding of reservoir
potential.
AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.