Abstract:

To prevent the water block damage induced by any extraneous fluid's invasion during drilling and completion operations in low-permeability gas reservoirs，a high-performance anti-water blocking agent（FWB），which is composed of hydrogen-rich block silicone oil and some additives such as organosilicon surfactant and deformer，was developed for low-permeability gas reservoirs. The infrared spectroscopy was used to characterize the molecular structure of the block silicone oil，and a series of tests，which include surface tension test，contact angle test，core imbibition test，permeability recovery ratio test，and drilling fluid compatibility test，were conducted to comprehensively evaluate the performance of this anti-water blocking agent. The test results show that，at the mass concentration of 1%，it can dramatically reduce the surface tension of the aqueous phase to 22.28 mN/m，increase the contact angle of the aqueous phase from 29° to 120°，decrease the core imbibition amount by 69.2%，and improve the permeability recovery ratio to 89.3%，and that it has good compatibility with drilling fluids. This anti-water blocking agent can significantly reduce the water block damage during drilling and completion operations and provide effective protection for low-permeability oil and gas reservoirs. 

Key words:

low-permeability gas reservoir, anti-water blocking agent, block silicone oil, permeability recovery ratio, contact angle, reservoir protection

摘要： 针对低渗气藏钻完井过程中外来流体侵入引发的水锁损害问题，以高含氢嵌段硅油为主剂，复配有机硅表面活性剂、消泡剂等助剂，制备了一种适用于低渗气藏的高性能防水锁剂FWB。采用红外光谱对嵌段硅油的分子结构进行了表征，并通过表面张力法、接触角法、岩心自吸法、渗透率恢复率实验和钻井液配伍性等实验综合评价了防水锁剂FWB的性能。实验结果表明，1%防水锁剂FWB可将水相表面张力大幅降低至22.28 mN/m，将水相接触角由29°提高至120°，岩心自吸水量的减少幅度达69.2%，且渗透率恢复率可提高至89.3%。该防水锁剂具有良好的钻井液配伍性。研制的防水锁剂FWB可以显著降低钻完井过程中的水锁损害程度，能有效保护低渗油气储层。

关键词:

低渗气藏, 防水锁剂, 嵌段硅油, 渗透率恢复率, 接触角, 储层保护