钻具和环空双密度钻井液碳酸盐岩储层钻井工艺

Drilling technology for carbonate reservoir with dual density drilling fluid of drilling tool and annulus

碳酸盐岩储层非均质性强,同一层段可能存在多套压力系统,钻井过程中易发生恶性漏失、溢漏同存等复杂,常规钻井工艺无法有效平衡安全钻进与钻井成本的问题,为此提出基于水眼和环空的双密度非常规钻井技术,根据井况在环空和钻具水眼内采用不同密度的钻井液,不建立循环进行钻进,通过测量环空液面高度及套压等方式实时跟踪地层压力变化情况,及时优选钻井液密度,实现在复杂地层的快速钻进。塔里木油田不同区块完成10余口井现场应用,使用低密度钻井液成功多钻进尺1881.62 m,在多打进尺的同时降低钻井液成本。应用结果表明,该技术可在不堵漏、不增加其他设备的情况下穿越恶性漏失层及油气活跃频繁出现高套压的地层,在大幅提高生产时效的同时实现成本节约,能满足轨迹监测需求,必要时可定向钻进以保证轨迹符合设计要求。该技术可实现最大限度钻揭储层,最大化实现地质目的及释放产能,进一步满足高效开发的要求,具有较好的应用前景。

Due to the strong heterogeneity of carbonate reservoirs,multiple sets of pressure systems may exist in the same formation,leading to incidents such as coexistence of severe circulation loss and overflow.Conventional drilling techniques fail to effectively balance the issues of safe drilling and drilling costs.To address this,a dual-density unconventional drilling technology based on bit nozzle and annular space was proposed.Different densities of drilling fluids were used in the annular space and the bit nozzle on drilling tool,eliminating the need for circulation during drilling.Simultaneously,the changes in formation pressure were monitored in real time by measuring the annular fluid level and casing pressure,and the optimal drilling fluid density was promptly selected,enabling rapid drilling in complex formations.This technology was successfully applied in over 10 wells in different blocks of the Tarim Oilfield,achieving a successful penetration depth of 1881.62 meters using low-density drilling fluid,which not only increased the penetration depth but also reduced drilling fluid costs.The application results show that this technology can penetrate formations with severe circulation loss and frequent high casing pressure without causing plugging or requiring additional equipment.This technology significantly improves production efficiency while achieving cost savings,which meets well trajectory monitoring requirements and can be directionally drilled when necessary to ensure the trajectory conforms to design specifications.This technology can maximize reservoir exposure,achieve geological objectives,release production capacity,and further meet the requirements of efficient development,demonstrating promising application prospects.