适用于深层页岩气储层的高效水基钻井液体系研究及应用

RESEARCH AND APPLICATION OF HIGH EFFICIENCY WATER-BASED DRILLING FLUID SYSTEM SUITABLE FOR DEEP SHALE GAS RESERVOIR

针对深层页岩气储层钻井时易出现井壁失稳的现象,考虑到油基钻井液的环保以及成本压力,结合深层页岩气储层基本特征,室内通过关键处理剂的优选及评价实验,研究出了一套适合深层页岩气储层的高效水基钻井液体系,并评价了体系的综合性能。结果表明,该钻井液体系在140℃下老化后各项性能稳定,具有良好的流变性、润滑性、抑制性和封堵性能,另外,钻井液体系中加入膨润土、钻屑和CaCl2污染后,各项基本性能变化也不明显,体系抗污染能力较强。现场应用试验结果表明,研制的高效水基钻井液体系性能稳定,施工过程中未出现井壁失稳等井下复杂情况,能够满足深层页岩气钻井施工对钻井液的要求。

Aiming at the wellbore instability in deep shale gas reservoir drilling,considering the environmental protection and high cost of oil-based drilling fluid,combined with the basic characteristics of deep shale gas reservoir,a set of high-efficiency water-based drilling fluid system suitable for deep shale gas reservoir has been developed through laboratory optimization and evaluation experiments of key treatment agents,and the comprehensive performance of the system has been evaluated.The results show that the drilling fluid system has good rheological,lubricating,inhibiting and plugging properties after aging at 140℃.In addition,after adding bentonite,drilling cuttings and CaCl2 pollution into the drilling fluid system,the basic performance changes are not obvious,and the anti-pollution ability of the system is strong.Field application test results show that the developed high-efficiency water-based drilling fluid system has stable performance,and there are no complex downhole conditions such as borehole wall instability in the construction process,which can meet the requirements of drilling fluid for deep shale gas drilling.