胜利油田东部油区页岩油气水平井固井技术

Cementing technologies for shale oil and gas horizontal wells,eastern oil block,Shengli oilfield

胜利油田东部油区页岩油气使用水平井开采,针对高温高压长水平段固井所面临的现场下套管困难、环空界面胶结环境差、施工前井筒漏失、施工后气窜气侵等一系列技术难题,采用两亲冲洗隔离液、纤维膨胀和塑性胶乳防窜水泥浆体系以及相关配套技术措施共同组成了固井技术方案,解决了技术难题。室内实验评价结合现场施工应用,研究成果表明:①两亲冲洗隔离液可有效清除油基钻井液附着套管壁油膜和井壁含油滤饼,改善环空界面胶结环境,为固井质量提供前提保障;②塑性胶乳防窜水泥浆具有低失水、零游离液、沉降稳定性好、防窜性能好、水泥石抗压强度高和弹性模量低等性能优点,有效保证了长水平段固井界面胶结质量;③纤维膨胀水泥浆具有良好的堵漏防漏效果,在固井施工中可实现前期防漏,提高地层承压能力;④优化扶正器、漂浮顶替、环空压稳、辅助下套管等配套技术措施,使长水平段套管居中度得以保证,并解决了水泥浆在候凝失重过程中水平段油层无法压稳的难题;⑤将上述固井关键技术,现场应用于胜利油田东部油区4口页岩油气水平井,固井质量优,后期压裂开采效果好,为今后页岩油气水平井固井提供借鉴。

Horizontal-well drilling has been always used for shale oil and gas,eastern oil block,Shengli oilfield.But,horizontal-well cementing especially with long horizontal segment under high temperature and pressure is facing a series of technical problems such as difficulty in running casing,poor cementing environment at the annular interface,lost circulation before cementing,and gas channeling or invasion after cementing.Thus,several solutions have been proposed,for example adopting amphiphilic flushing spacer fluid,fiber expansion,plastic latex anti-channeling cement slurry system,and related supporting techniques.And these solutions were conducted by experimental evaluation and field application.Results show that(1)the spacer fluid can effectively remove both oil film on casing wall and oily filter cake at sidewall caused by oil-based drilling fluid,thereby making cementation environment better at annular interface to provide the prerequisite guarantee for cementing quality;(2)the anti-channeling cement slurry boasts low water loss,zero free liquid,good subsidence stability,right anti-channeling performance,high anti-compressive strength of cement stone,and low elastic modulus,which can effectively ensure the quality at the cementing interface in long horizontal segment;(3)the expansion cement slurry boasts superior plugging and anti-leakage effect to implement an early prevention during cementing and mend pressure-bearing capacity;(4)the supporting techniques,such as centralizer optimization,floating displacement,annular stabilization,and auxiliary casing running,can not only assure the centering of casing with long horizontal segment but solve the problem that oil layer in horizontal segment cannot keep stable pressure during the waiting on cement and weight loss;and(5)the above solutions have been used for 4 shale oil and gas horizontal wells in this block,achieving better cementing quality and subsequent fracturing effect,which may provide a reference for the future cementing of similar wells.