深层页岩气油基钻井液承压堵漏技术

Enhancing Pressure Bearing Capacity of Formation to Control Mud Losses in Deep Shale Gas Drilling With Oil Base Drilling Fluids

随着涪陵页岩气向深层开发,钻井液密度达到1.75 g/cm3,固井水泥浆密度达到1.85~1.89 g/cm3,为了提高固井质量,防止水泥浆漏失,需要提高油基钻井液应用井段承压能力。国外新型油基堵漏材料在涪陵二期深层页岩气焦页XX井进行了应用。应用效果表明,该技术能够实行随钻封堵,对钻井液的流变性能没有副作用,在提承压作业过程中,对部分漏失层段进行承压作业,承压能力能够从1.75 g/cm3提至1.80 g/cm3。最后对全部漏失层段进行承压作业,采用国外油基堵漏剂和自研油基堵漏材料T150联合堵漏,承压能力提高至1.85 g/cm3。研究结果表明,该油基堵漏技术适用性强,配方简化,亲油性强,可操作性好,可以进行推广应用。

With the advancement of shale gas drilling to deeper reservoirs, the density of drilling fuid has approached 1.75 g/cm , and the density of cement slurry approached 1.85-1.89 g/cm^3. To improve the quality of well cementing and prevent the losses of cement slurry, the pressure bearing capacity of the open hole to oil base drilling fuids should be improved. The application of an imported new lost circulation material （LCM） for use in oil base mud on the deep shale gas well Jiaoye-XX （a well drilled in the second phase of shale gas development in Fuling, Sichuan） showed that the oil base mud LCM is able to plug lost circulation zones while drilling, and imposes no negative effect on the rheology of the drilling fuid. The pressure bearing capacity of part of the lost circulation zones was enhanced, from pressure bearing capacity of 1.75 g/cm^3 to 1.80 g/cm^3. Finally, all the lost circulation zones had their pressure bearing capacity enhanced. Using the imported LCM and an oil base mud LCM T150 of independent intellectual property rights, the pressure bearing capacity of the formations prone to lost circulation was enhanced to 1.85 g/cm^3. Study results showed that control of oil base mud losses with the two strongly LCMs is widely applicable and easy to operate. The two strongly lipophilic LCMs are a worth popularizing in controlling oil base mud losses.