J45断块盐下水平井钻井关键技术

Key technologies for drilling horizontal wells in the subsalt layer of Fault Block J45

冀中坳陷束鹿凹陷J45断块地质条件复杂,沙河街组一段地层底部发育大段盐膏岩,该盐膏岩蠕变速率快、蠕变非均匀应力大,且对井筒工作液污染严重,其下部紧邻沙河街二段储层产状变化较快,内部单个砂组厚度较薄。针对以上情况,从井眼轨道设计、储层轨迹控制、套损套变预防和固井质量保证等方面着手,分析、整理出该断块水平井开发时存在的难点,并针对性采用了双增六段制剖面设计、地质工程一体化导向、双层组合套管注机油及抗盐水泥浆体系等系列技术对策。通过4口水平井的现场应用及不断改进,逐步形成了J45断块独有的盐下水平井钻井配套技术。

Fault Block J45 in Shulu Sag of Jizhong Depression is geologically complex.A thick salt gypsum layer,whose creep rate and heterogeneous stress are high,is developed at the bottom of the first Member of Shahejie Formation,and it brings serious damage to the well working fluid.It is directly underlain by the second Member of Shahejie Formation,whose occurrence varies faster and internal single sand body is thinner.Considering these situations,the difficulties in the horizontal well development of this fault block were analyzed and summarized from the aspects of hole trajectory design,reservoir track control,casing damage and deformation prevention and cementing quality control.In addition,a series of technological countermeasures were adopted correspondingly,including double-buildup six-section profile design,geology-engineering integrated steering,double-layer casing for machine oil injection and salt-resisting slurry system.Based on their field application in four horizontal wells and continuous improvement,the unique supporting technologies for drilling horizontal wells in the subsalt layer of Fault Block J45 are developed gradually.