Following the basic theory of protecting gas-reservoirs from damage with the temporary bridging technology,inert calcium carbonate (CaCO3) particles,whose diameter is consistent with the size of pores or apertures in ...Following the basic theory of protecting gas-reservoirs from damage with the temporary bridging technology,inert calcium carbonate (CaCO3) particles,whose diameter is consistent with the size of pores or apertures in the reservoir,were selected as the bridging agent,and modified resolvable starch was selected as filtration loss reducing particles to form the non-clay low damage temporary bridging drilling/completion fluids system (NLTDFS). Under the simulated condition of the well bottom during real drilling,NLTDFS was used to conduct dynamic and static damage experiments of cores for 48 hours,respectively,and then the experimented cores were permeated with pure nitrogen from the undamaged end to the damaged one to measure their recovery of permeability. The results showed that the permeability recovery rate of the core reached 90% or so,and the damaged depth was less than 1 cm,which demonstrates that NLTDFS has higher temporary bridging effectiveness and lower damage to the gas-reservoir than other drilling fluids system. NLTDFS has been used to drill many horizontal wells,and four of them have obtained high yield of natural gas. The yield of natural gas of LP1 well reached 85×104 m3/day after completion with the rump pipe. The formation of the stable well wall and smooth drilling led to an API loss less than 4 mL and an HTHP loss less than 15 mL.展开更多
琼东南盆地属于中孔低渗储层,储层易发生水化、水锁等伤害。当前区块系列井所用深水钻井液侵入损害类型、机理不明,且传统的钻井液伤害评价方法误差大,不能直观地量化损害程度。因此设计了以钻井液污染实验、扫描电子显微镜(scanning el...琼东南盆地属于中孔低渗储层,储层易发生水化、水锁等伤害。当前区块系列井所用深水钻井液侵入损害类型、机理不明,且传统的钻井液伤害评价方法误差大,不能直观地量化损害程度。因此设计了以钻井液污染实验、扫描电子显微镜(scanning electron microscope,SEM)分析、计算机断层扫描(computed tomography,CT)结合的方式分析钻井液固相以及液相侵入损害储层的方法。结果表明,深水钻井液与地层水配伍性良好,储层水锁损害率处于19.8%~31.4%,液相侵入损害主要为水锁损害;岩心SEM扫描结果显示其孔隙连通性差,EDS测试结果中Ba^(2+)、Ca^(2+)含量较高,分析固相侵入损害主要由加重剂引起,且蒸馏水返排后岩心CT扫描结果显示孔隙度微幅上升表明固相堵塞很难通过自然返排的方式清除。于是通过研发降滤失剂和优选加重剂粒径配比的手段优化深水钻井液储层保护性能。根据理想充填理论,确定最佳配比为1000目CaCO_(3)、600目CaCO_(3)和200目CaCO_(3)的比例为5∶11∶9。优化后体系滤失量显著降低,固相颗粒中径在90μm左右,滤饼致密程度明显提高;渗透率恢复值提高12.1%~19.68%,对该区块钻井液储层保护性能优化具有指导意义。展开更多
文摘Following the basic theory of protecting gas-reservoirs from damage with the temporary bridging technology,inert calcium carbonate (CaCO3) particles,whose diameter is consistent with the size of pores or apertures in the reservoir,were selected as the bridging agent,and modified resolvable starch was selected as filtration loss reducing particles to form the non-clay low damage temporary bridging drilling/completion fluids system (NLTDFS). Under the simulated condition of the well bottom during real drilling,NLTDFS was used to conduct dynamic and static damage experiments of cores for 48 hours,respectively,and then the experimented cores were permeated with pure nitrogen from the undamaged end to the damaged one to measure their recovery of permeability. The results showed that the permeability recovery rate of the core reached 90% or so,and the damaged depth was less than 1 cm,which demonstrates that NLTDFS has higher temporary bridging effectiveness and lower damage to the gas-reservoir than other drilling fluids system. NLTDFS has been used to drill many horizontal wells,and four of them have obtained high yield of natural gas. The yield of natural gas of LP1 well reached 85×104 m3/day after completion with the rump pipe. The formation of the stable well wall and smooth drilling led to an API loss less than 4 mL and an HTHP loss less than 15 mL.
文摘琼东南盆地属于中孔低渗储层,储层易发生水化、水锁等伤害。当前区块系列井所用深水钻井液侵入损害类型、机理不明,且传统的钻井液伤害评价方法误差大,不能直观地量化损害程度。因此设计了以钻井液污染实验、扫描电子显微镜(scanning electron microscope,SEM)分析、计算机断层扫描(computed tomography,CT)结合的方式分析钻井液固相以及液相侵入损害储层的方法。结果表明,深水钻井液与地层水配伍性良好,储层水锁损害率处于19.8%~31.4%,液相侵入损害主要为水锁损害;岩心SEM扫描结果显示其孔隙连通性差,EDS测试结果中Ba^(2+)、Ca^(2+)含量较高,分析固相侵入损害主要由加重剂引起,且蒸馏水返排后岩心CT扫描结果显示孔隙度微幅上升表明固相堵塞很难通过自然返排的方式清除。于是通过研发降滤失剂和优选加重剂粒径配比的手段优化深水钻井液储层保护性能。根据理想充填理论,确定最佳配比为1000目CaCO_(3)、600目CaCO_(3)和200目CaCO_(3)的比例为5∶11∶9。优化后体系滤失量显著降低,固相颗粒中径在90μm左右,滤饼致密程度明显提高;渗透率恢复值提高12.1%~19.68%,对该区块钻井液储层保护性能优化具有指导意义。
