煤层气生物酶可解堵钻井液的岩心流动实验研究

Laboratory Core Flow Research on Enzyme Biodegradable Drilling Fluid Used for Coal Bed Methane

为解决煤层钻井井眼净化、井壁稳定和储层保护之间的矛盾,采用生物酶可解堵钻井液技术进行黏度衰减实验,验证了聚合物与生物酶最优匹配性研究,对8种生物酶可解堵钻井液材料进行了岩心流动实验和金相显微观察实验,用固液耦合法分析了影响生物酶在岩心中解堵聚合物的可能因素。岩心流动实验结果表明:生物酶对特定聚合物的解堵速率:酶C>酶B>酶A>酶F;采用特定生物酶破胶,岩心渗透率恢复率可达70%以上;可解堵钻井液用于煤层气钻探具备前期稳定井壁后期降低对煤储层伤害的特性。

To solve the contradiction between borehole cleaning,wellbore stability and reservoir protection,the enzyme biodegradable drilling fluid system is applied.In laboratory,the viscosity decay test is used to optimize the enzyme matches the polymer best,and eight kinds of materials that can be used for biodegradable drilling fluid are tested with the core flow experiment and metallographic microscopic observation test.Solid-liquid coupling method is carried out to analyze the factors influencing the degradation of polymers.The experimental results show that gradation rate of particular polymer with enzyme is C>B>A> F and by using specific enzyme breaking gel,the core permeability recovery rate is over 70%,so that the biodegradable drilling fluid has characteristics of keeping wellbore stability and reducing reservoir damage for coal bed methane drilling.