GJ-1 cement slurry system for gas reservoir protection and its laboratory evaluation

As a system used in plugging gas reservoir, GJ-1 cement slurry for gas reservoir protection has been developed based on analyzing the requirement of the cement slurry in lowpermeable gas field and the mechanism of the cement slurrypreventing gas channeling,as well as the interaction of the cement slurry additives. The properties of cement slurry and cement stone are tested from macroscopic to microcosmic and the results show that the inner microcosmic structure of cement slurry stone has been adjusted by cement additives; tenacity and impact resistance of cement stone have been improved; degree of cement slurry polluting producing pay has been reduced because of the low filtrate, etc. . The cement slurry has the characteristics of plastic latex and has good abilities of irreducible free water, solid fine particle and improving interfacial cementation, meanwhile, compact strong gel film can be formed in low filtrate condition so that the cement slurry has quite act of preventing formation fluid channel into annular space in curing time and reduce the plastic factor of the cement slurry. Because of these reasons, the cementing quality of gas layer has been improved, oil, gas and water channeling have been prevented and reservoir has been protected.