Page 234 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

218 Gas Wettability of Reservoir Rock Surfaces with Porous Media

precursor. Nano-polysilicon and the surfactant can be adsorbed on the rock
surface to alter its wettability and improve the relative permeability of the
water phase. In 2006, Yang Jainhua et al. realized that pressure decreases when
the injection increases in water-injection wells by acid treatment of water
wells. This helped achieve desirable effects in the field and properly addressed
the issues faced in water-injection of low-permeability reservoirs. In 2008, Li
Yanjun et al. studied and found that the wettability of reservoirs altered
through the surface effects of nano-polysilicon materials, or that the chemical
treatment of surfactants decreased pressure and increased water injection in
low-permeability reservoirs. Also, chemical treatment may increase crude oil
recovery and address insufficiencies encountered with conventional chemical
oil-displacing technology in low-permeability reservoirs. In 2006, Liu Y., et al.
prepared a new type of chemical substance, realized gas-wetting alteration of
rock surfaces in reservoirs and increased the relative permeability of gas and
water phases. The production capability increased by 2B3 times. In 2008, Yao
Tongyu et al., studied the capability and features altering the wettability of
artificial cores to gas wettability through chemical agents, including sodium
dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, octyl phenol
polyoxyethylene ether OP215, simethicone GB2201, and dichlorodimethylsi-
lane. They also studied their effects on the permeability of gas and liquid
phases, and measured the relative permeability of these phases before and
after changes in wettability of cores.

The above research illustrates that the tendency for decreasing pressure and
increasing injection in low and extra-low-permeability water-injection
reservoirs is as follows: technology involving decreasing pressure and increas-
ing injection of polysilicon nanomaterials, technology involving a combina-
tion of nanomaterials and surfactants, and gas-wetting alteration technology
of condensate gas reservoirs. These technologies decrease pressure and increase
injection by changing the wettability of rock surfaces.
The concept of “trapezoid protection technology for low-permeability water-
injection reservoir” is described in this section: ① By modifying the quality
of injected water, the properties of rock surfaces in water-injection reservoirs
are changed, and hydration swelling of clay minerals and water-block dam-
age are prevented. Meanwhile, the increase in pressure during injection is
slower, and the injection capability and water-displacing-oil efficiency are
improved. ② During construction, a certain injection method is adopted to
improve the quality of injected water gradually, to reduce costs, etc., and
resolve problems including rapidly rising pressure, low injection volume,
and shorter effective time period for low and extra-low-permeability water-
injection reservoirs.
In case of problems like hydration swelling and water-block damage that
universally exist in low- and extra-low-permeability water-injection reservoirs,
trapezoid protection agent A, which features excellent antiswelling and
antiscaling effect, and trapezoid protection agent B, which boasts good oil