应用高性能多元醇钻井液保护深层低渗透油气藏

High-performance polyalcohol drilling fluid applied to protection of ultra-deep reservoir with low permeability

准噶尔盆地中部3区块的深层油气藏具有低渗透储层的典型特征,表现为含水饱和度高、孔喉细小、渗透性差、结构复杂、非均质性严重、油气流动阻力大及常伴有天然裂缝等特点。经岩心流动实验证实,水锁是损害该低渗透储层的主要因素之一,渗透率损害率为49.3%-89.2%。应用防液锁技术、理想充填理论及d90规则,研发了具有防水锁、低侵入特点的高性能多元醇钻井液。通过配伍性实验、表面-界面张力评价实验、动态污染实验及水锁实验,对该钻井液的储层保护特性进行了评价。室内实验及现场应用结果表明,该钻井液不仅能够满足超深井安全快速钻井的需要,而且多元醇SYP-1与表面活性剂HAR之间的协同作用能显著降低滤液表面张力和滤液-油界面张力,提高钻井液返排效率,减轻深层低渗透储层水锁损害。

The deep reservoir in the Block 3 of the center part of Junger Basin is commonly characterized by high initial water saturation,high capillary pressure,complicated structure,serous heterogeneity,high oil-gas flow resistance and natural fractures.Laboratory core tests confirmed that one of factors for severe damage of reservoir was water blocking effect caused by aqueous invasion fluids during drilling and production operations.The damage extent of permeability ranges from 49.3% to 89.2%.By adopting the liquid trap prevention method,ideal packing theory and d90 rule,a high-performance drilling fluid was developed,which was composed of polyalcohol SYP-1,efficient water blocking preventing surfactant HAR and temporary bridging agents.The protection characteristics of fluid to reservoir were verified by compatibility test,surface and interfacial tension test,dynamic damage test and phase trap test.The test results and field data showed that the fluid system could satisfy the safe and fast requirement of ultra-deep drilling operation.The synergy of HAR and SYP-1 could efficiently minimize water blocking,reduce the surface-interfacial tension and improve the displacement rate of drilling fluid.