Single Slot Dual Wells Casing Cutting Technology for Offshore Oil Field

Among the treatment measures for inefficient Wells in offshore oil fields, the lateral drilling technology of shallow casing retrieve is a simple and effective method. However, due to the increasing number of old platforms with single barrel and double wells in offshore oil fields, the conventional single-barrel single-well shallow cutting and casing retriveve technology has been unable to meet the operational requirements due to the problem of shallow layer collision prevention. The main purpose of this article is to solve these problems with current technologies and tools. The main technical methods and ideas are as follows:casing cutting decision tree demonstration analysis, casing cutting point anti-collision analysis and hydraulic cutter optimization; According to CNOOC directional well collision prevention standard, three-dimensional quantitative analysis is carried out on the separation coefficient and center distance of cutting point collision prevention, so as to make it absolutely safe once cutter operates in the limit eccentric state. At the same time, according to the cutting casing size, layer number and pound grade, the optimal combination of hydraulic cutter type is optimized, and suitable milling tools are prepared to meet the urgent needs. The successful application of this technology in several oilfields in Bohai Bay not only creates a precedent of single-barrel double-well shallow cutting and casing pulling, but also greatly reduces the operating cost and risk. In the case of gas well or high gas-oil ratio well operation, it is suggested to abandon two wells or temporarily seal the lower part of them to avoid the accident of "cutting" adjacent wells caused by personnel's misoperation and data error. In the future, this technology can be tried and popularized in single-barrel wells and deep-water cluster wells.