适用于煤层气开采的低密度钻井液技术研究与应用

Study and application of light weight drilling fluid applied to coalbed methane development

针对煤储层井壁易坍塌、易受钻井液污染等难题,通过中空玻璃微球密度降低剂的优选及对钻井液性能的影响评价实验,研发了中空玻璃微球低密度钻井液体系。钻井液性能评价实验结果表明:该钻井液具有良好的流变性和滤失性,泥饼薄而致密,API失水量小于5 mL,高温高压失水量小于15 mL,120℃老化16 h后钻井液性能稳定,具有很好的抗温性;同时,该钻井液具有很好的抗污染性、防塌性、封堵性、沉降稳定性和保护储层作用。沁南示范区成功进行了1口井的现场试验,钻井液密度0.95 g/cm3,有效防止了液体对煤储层的污染,有利于后续的煤层气开采。

In view of the collapsibility of borehole face and coal formation pollution resulted from drilling fluid,developed the light weight drilling fluid through optimization experiments of hollow glass microspheres light weight additive and evaluation experiments of its influence on drilling fluid performances.The density of the developed light weight drilling fluid was reduced by adding hollow glass microspheres.The evaluation experiments of drilling fluid performances show that the light weight drilling fluid has good rheological property and filtration property,and its mud cake is thin and tight,its API filtration loss is less than 5 mL,and is less than 15 mL at high temperature and pressure,and after aging 16 h at 120 ℃,the drilling fluid performance is stable,which shows that it has good temperature tolerance.Moreover,this drilling fluid has a lot of good properties,such as antipollution,anti-sloughing,blocking,sedimentation stability and formation protection.This light weight drilling fluid,whose density is 0.95 g/cm3,was applied in one well for field trial successfully at Qinnan demonstration plot.Good performanc on protecting coal formation from pollution,which is good for sequent development of coalbed methane,was observed.