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

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.