气井储层水锁效应解除措施应用

THE APPLICATION OF RELIEF MEASURES FOR WATER LOCK EFFECT IN RESERVOIRS OF GAS WELLS

低渗气藏的通道较窄,渗流阻力较大,液、固界面和液、气界面的表面张力较大。这使得气井在生产过程中,由于地层水或外来流体(尤其是钻井液、压井液、酸化液和压裂液等)未排干净,致使气井储层气相相对渗透率下降,从而造成储层水锁,严重地影响气井产能的发挥。储层气相相对渗透率取决于孔隙介质中的含水饱和度和在水存在的情况下气体的分相流动特点,因此通过降低近井地带储层含水饱和度,改变气体的分相流动特性可以解除水锁效应。室内评价实验及现场试验表明,使用由表面活性剂和低毛细管力酸液复配而成的气井解堵剂解除了气井储层的水锁效应,提高了产层气相渗透率,使气井的产气量得到明显提高。

Low-permeability gas reservoirs are characterized by narrow channels, relatively great percolating resistance, relatively great surface tension of liquid-solid and liquid-gas interface, which makes the relative decline of gas well reservoirs permeability and results in water lock of reservoir, seriously affecting gas wells production, for the reason that formation water or external fluid (especially drilling fluid, killing fluid, and acidizing and fracturing fluid, etc.) is not drained away in the production process of gas wells. The relative permeability of gas information in gas wells is determined by the characteristics of water saturation in porous medium and the gas fractional flow with the existence of water. Therefore, by reducing the water saturation in reservoirs near well-bore area and changing the fractional flow of gas, the water lock effect can be relieved. Laboratory evaluation tests and field tests showed that the gas well plugging agent, which compounded by surfactants and low capillary acidizing fluid, can relieve the water lock effect in gas reservoir, increase gas phase permeability of producing formation, and enhance gas production of gas wells significantly.