表面活性剂压裂液的防水锁增产机理实验

Experimental of water unlocking stimulation mechanism on surfactant fracturing fluid

以进一步探索表面活性剂压裂液(1.5%KCl+0.05%AN)的防水锁增产机理为目的,采集河东煤田柳林地区沙曲矿的焦煤作为研究对象,通过表面张力和接触角测试、渗透率伤害实验、变压解吸实验,探讨煤储层水锁伤害的控制方法,揭示表面活性剂压裂液防水锁增产作用机理。研究结果表明:表面活性剂压裂液具有极低的表面张力和界面接触角,具备降低煤储层孔喉毛细管压力、增强压裂液可排性的能力,使得其水锁伤害率比活性水压裂液降低约40%,能够有效抑制煤储层的水锁伤害;这种防水锁作用不仅能够提高煤储层束缚水状态下的气相渗透率,实现增透增产,而且还能降低煤层气产出的临界孔径以促进煤层气解吸,实现增解增产。

This paper presents an experimental study of water unlocking stimulation mechanism on surfactant fracturing fluid based on the measurements of surface tension,contact angle,gas-phase permeabilities and desorption of nitrogen on synthetic coal samples.The coking coal in Liulin zone of Hedong coal field was used as testing object in this study.Active water and surfactant fracturing fluids were used as testing liquids in this study.Results show that the surfactant fracturing fluid(1.5%KCl+0.05%AN)reduces the surface tension of active water fracturing fluid(1.5%KCl)and increases the wettability of active water fracturing fluid to coal reservoir;the surfactant fracturing fluid reduces the capillary pressure of fluid in coal pore to make the fracturing fluid easily access into the coalbed methane reservoir;the surfactant fracturing fluid can reduce the water blocking damage rates of coal reservoirs by about 40%;and the surfactant fracturing fluid inhibits the occurrence of water blocking damage efficiently.Regarding to the coalbed methane reservoir,the surfactant fracturing fluid has the stimulation effect.It is concluded that the surfactant fracturing fluid increases the gas-phase permeabilities at bound water saturation of coal reservoir,thus realizing the permeability increasing,and the surfactant fracturing fluid reduces the critical diameter of coalbed methane production,thus realizing the desorption increasing.