The deep sidetrack wells of Tahe oilfield require to meet requirements of avoiding water, and drill to the leakage zone and collapse area of carboniferous system, two pressure systems need to be drilled, which traditional drilling fluids and chemical plugging method can’t ensure drilling safety, and if running the conventional casing into the hole, drilling and completion face many difficulties because of following slim hole. All above making the old deeply areas remaining oil can’t be liberated. Expandable casing technology is a new technology, which acts as intermediate casing to block complex formation during drilling. It can optimize the structure of the well bore, block abnormal high pressure layer, collapsed layer and leaking layer, providing a technical plan to drill successfully to the target for complex deep wells. According to the developing difficulties of Φ177.8mm casing deep sidetrack horizontal wells in Tahe oilfield, it produces a solution of expandable casing, analysis the operating difficulties of expandable casing, proposes an expandable casing technology solution, adopts unconventional diameter 130mm borehole drilling after expanded. It also describes in detail the drilling block application of expandable casing technology for the first time in the sidetrack horizontal well. Field application shows that expandable casing drilling technology program designed can solve the drilling problem of the deep sidetrack horizontal well of the Tahe oilfield, and gains good technical practice. The effect of application confirms that the expandable casing implementation can meet the drilling block and follow unconventional slim hole drilling requirements. In conclusion, the expandable casing drilling technology is the first time for technical casing of sidetrack horizontal wells , which proves the practicability of expandable casing drilling solution, and provides a new way to solve the development problems in Tahe oilfield. Meanwhile we successfully solves the unconventional diameter 130mm borehole drilling problem, using the non-standard small-diameter MWD instrument and non-standard diameter 89mm drill pipes for the first time, perfects slim hole drilling process. Furthermore, this application successfully provides the technical foundation of expandable casing technology in complex stratigraphic drilling.
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