Page 192 - Air and gas Drilling Field Guide 3rd Edition

CHAPTER

Air, Gas, and Unstable

Foam Drilling 8

Deep drilling operations with air and gas drilling technology are used in the
recovery of oil and natural gas and in the recovery of geothermal steam and hot
water. In the late 1970s, it was estimated that air and gas drilling technology was
being used on only about 10% of the deep wells drilled and completed [1, 2].
Today, most of the world’s oil and natural gas producing fields are in mature sedi-
mentary basins. The application of air and gas drilling technology is usually
limited to either (1) performance drilling operations in competent rock forma-
tions or (2) underbalanced drilling operations in low pressure reservoirs (i.e.,
in-fill operations). In the latter operations, the reservoirs are usually sensitive to
formation damage caused by traditional mud drilling operations. The advantage
of air and gas drilling operations is that the bottom hole annulus pressures can
be designed to be below the reservoir bottom hole pressure. The existence
of extensive formation damage using traditional drilling technology has led to
the development of underbalanced drilling and completion technology. Even
though underbalanced drilling and completion operations have applications in
low mud weight drilling operations, the vast majority of these operations utilize
air and gas drilling technology. Currently, it is estimated that approximately 30%
of land-based oil and natural gas recovery drilling and completion operations
utilize some form of air and gas drilling technology (either as a performance
drilling operation or as an underbalanced drilling operation). As more oil and
natural gas producing fields mature throughout the world, this percentage will
increase.
This chapter outlines the steps and methods used to plan a successful deep
air and gas drilling operation. This chapter also illustrates the application of
these steps and methods to the planning of a typical deep drilling operation.
The objective of these steps and methods is to allow engineers and scientists
to cost-effectively plan their drilling operations and ultimately select their dril-
ling rig, compressor package, and other auxiliary drilling location equipment.
The additional benefit of this planning process is that data created by the process

183