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230 Gas Wettability of Reservoir Rock Surfaces with Porous Media

with NaHCO 3 as the water type. When trapezoid protection technology was
used in this oilfield, the injection pressure was maintained between
3
13B15 MPa, with the daily volume between 50B60 m . The phenomenon
that results in failure of injection due to plug formation or significantly declin-
ing injection volume has not occurred during the last year, and the protection
to reservoirs has been maintained.

6.4 MICROEMULSION OIL REMOVAL TECHNOLOGY
6.4.1 Research Status of Cutting Processing Technology

Oil removing technology is being used to process oil-based drilling fluids,
which were used by some countries overseas and have now become more
advanced. Currently, there are several oil-cutting technologies, such as reinjec-
tion, pyrolysis, drilling, cleaning cuttings method, centrifugation, bioanalysis,
ultrasonic method, and water-jet oil removal method. All of them have their
respective advantages and drawbacks. This text generalizes and summarizes
several kinds of processing technologies.

6.4.1.1 CUTTING REINJECTION TECHNOLOGY
The cuttings generated during the drilling process are mixed with drilling
fluids, seawater, and other applicable injected liquids, and then reinjected into
the formation through casing annular space or perforated casings [35 42].
With the development of cutting reinjection technology, the injection technol-
ogy is not limited to oil-bearing cuttings any more, and includes reinjections,
like waste oil-based drilling fluids, waste water-based drilling fluids, and
saline. The reinjection technology achieves zero discharge of oily waste and is
quite a good method to process oily waste in offshore drilling, remote places,
and environmental limits, but domestic applications are less, due to inefficient
cost control and formation condition limitations.

6.4.1.2 PYROLYSIS METHOD
Water and oil are desorbed from solid waste by heating and then the oils are
recycled, while the waste residue is collected [43]. Pyrolysis is a better method
for centrally and commercially processing oily cuttings. Oil can be completely
processed and recycled, but it is not economical to process on a small scale.
Waste gases, powders, and noise require special processing, and secondary pol-
lution may arise if the process is incorrect.
Existing devices for pyrolysis included rum-type indirect pyrolysis devices,
screw pyrolysis devices, hammer-mill types, and chemical pyrolysis devices.
The required temperature and processing methodology are all different for
each device processing oily cuttings. Among them, the hammer-mill can
smash oily cuttings to a micron in diameter. The interior structure of cuttings
and oil in pores don’t exist anymore, and the petroleum hydrocarbon content
in processed cuttings is less than 0.1% [44,45].