青海油田英西深层水平井固井技术

青海油田英西狮子沟区块深层油气藏是近年来柴达木盆地油气勘探的重大突破，该区块资源潜力巨大，同时复杂的钻井、地质条件给固井质量和后续开采带来了巨大的挑战。针对该区块水平井多级压裂的开发特点，为了建立有效的层间封隔，保持水泥环长期密封完整性，通过分析固井难点，完善了固井工艺，优选水泥浆和前置液体系，形成了一套适用于狮子沟水平井开发的固井技术。使用自愈合剂有效封堵水泥石出现的微裂缝，抑制油气窜流，使其同时具有弹性水泥特征，保证水泥环长期密封完整性。形成的基体抗侵防窜水泥浆体系具有一定触变性和较强的内部黏滞力，具有良好的"静止堵漏"效果，同时可降低窜流发生的风险。2018年以来，该固井技术在英西狮子沟区块应用20余井次，平均井深5000 m，平均水平段长1000 m，现场应用效果良好，满足后续体积压裂改造的技术需求，为英西深层开发提供关键配套技术，具有广阔的市场应用前景。 

Technology for Cementing Deep Reservoirs in Yingxi Area,Qinghai Oilfield

Qinghai Oilfield has in recent years found deep petroleum reservoirs in the Block Yingxi Shizigou. This is a major breakthrough in oil and gas exploration in the Qaidam Basin. This block not only has huge potential of oil and gas reserves, the complex drilling and geological conditions also bring about great challenges to well cementing operation and subsequent production. Since the horizontal wells in this block is stimulated with multistage fracturing, to establish effective zonal isolation and to maintain long-term seal integrity of the cement sheath, a special cement slurry and prepad fluid have been selected, based on the analyses of difficulties encountered in well cementing. The cement slurry, the prepad fluid and an improved set of well cementing techniques together formed a set of well cementing technology suitable for the horizontal wells drilled in block Shizigou. Using a self-healing agent, the micro-fractures generated inside set cement were filled and the set cement was thus rendered elasticity, ensuring the long-term seal integrity of the cement sheath. The anti-invasion anti-channeling cement slurry also has some thixotropic property and internal viscous force, which are beneficial to cement slurry loss control and channeling mitigation. Since 2018, this set of well cementing technology has been applied with great success in Shizigou for more than 20 times/wells, with average well depth of 5,000 m and average horizontal length of 1,000 m. Wells cemented with this technology satisfied the needs of subsequent spatial fracturing operation. As a key technology for the development of deep reservoirs in Yingxi, this technology will find wide application in the future.