抗高温高密度油基钻井液高效封堵剂研究与应用

DEVELOPMENT OF HIGH-SEALING-PERFORMANCE AGENT FOR HIGH-TEMPERATURE HIGH-DENSITY OIL-BASED DRILLING FLUID AND ITS APPLICATION

四川盆地页岩气储量丰富,但页岩层理发育,液体侵入后使井壁极易发生层间剥落。因此,如何从钻井液角度出发有效封堵页岩层间缝隙,减小液相侵入,防止井下垮塌,是页岩气开发必须解决的难题。同时,由于部分构造的页岩气井为深井超深井,井底温度高(≥180℃)、地层压力大(2.35 g/cm3),钻井液必须具有较高密度和较强抗高温能力。文章采用甲基丙烯酸甲酯和丙烯酸丁酯通过乳液聚合研发出一种适合于油基钻井液的、具有高效封堵能力的抗高温树脂微粒。该树脂微粒一方面提高钻井液对页岩地层的封堵能力,减少液相侵入地层造成的压力传递,解决井壁失稳的技术难题,另一方面降低处理剂加量从而改善高密度油基钻井液流变性。在现场应用过程中,为页岩气井威204H5-6井水平段安全快速钻进提供了技术保障,也为进一步推动我国页岩气"工厂化"开发进程奠定了坚实基础。

The shale gas reserves in Sichuan is abundant,but the shale beddings is highly developed,subject to scaling between formations after liquid phase intruded into. Therefore,how to effectively block off the crevices between shale beds to reduce the liquid invasion and thus avoid well casing is a problem of shale gas development must to be solved. At the same time,the shale gas wells at some structures are deep or ultradeep wells,with high BHT( ≥180℃),high formation pressure 2.35g/cm^3,the drilling fluid must have high density and able to work in high temperatures. A new high-performance sealing agent made of high-temperature resin grains is developed for OBM,able to improve the drilling fluid's performance to block off the shale formations to reduce the pressure transmission caused by liquid invasion and so to keep the wellbore stable,and its use will reduce the amount of agents to be added to improve the rheology of the high-density OBM. It was ever used to drill the horizontal interval of the shale gas well W204H5-6 well,the safe and fast drilling was guaranteed. It has also laid a solid foundation for pushing forward the factory development of China's shale gas.