Key drilling technologies of scoop-shape horizontal well in Hutubi gas storage

Hutubi gas storage is limited by the surface conditions, so in order to effectively produce the high-quality gas reservoir below the wellhead, the scoop-shape horizontal well drilling technology is adopted, which can increase horizontal section length and reservoir contact area and improve single well injection and production capacity effectively. Scoop-shape horizontal well is complex in well trajectory and drilling tool stress with greater drilling friction and torque, and reversal large-size hole whipstocking is adopted in Hutubi area, which brings greater challenges to horizon wells from aspects of well stability, well trajectory control, friction and drag reduction and rate of penetration (ROP) improvement. It is determined by the well stability analysis that the maximum horizontal principal stress is in the direction of 23° and the drilling along the maximum horizontal principal stress is the most stable. The safe running of the casing in the reversal whipstocking section is ensured by selecting drilling fluid system, optimizing drifting bottom hole assembly (BHA) and reducing friction and drag. The fourth spud in one trip is realized by means of well trajectory optimization, “one-tip” PDC bit and rotatory steering technology, which ensures the smooth drilling of scoop-shape horizontal well 7# in Hutubi. Compared with its contemporaneous neighboring horizontal well, its horizontal section is 245 m longer, its average ROP is 9.6% higher and its drilling cycler is 3.0% shorter. The successful implementation of scoop-shape horizontal well in Hutubi gas storage provides a powerful technological guarantee for the efficient development of Hutubi gas storage and a reference for the construction of gas storages rebuilt from oil and gas reservoirs in China.