Study and Application on Perforation Technology for Extended-reach and High-inclination Well in Offshore Field

It is an important way to develop fault block oil and gas reservoir economically and efficiently by sidetracking extendedreach well from old-well, which puts forward higher requirements for safety perforation technology in well completion. Well Pinghu AM1 is a ultra-deep, extended-reach and high-inclination well, the well depth is 6 866 m, the horizontal displacement is 5 350.49 m, the maximum inclination is 77.81°, the well section with inclination above 60° is 4 524 m. During perforation operation of these kinds of wells, a series of problems often occur, such as security of strings, depth correction with conventional wireline logging, monitoring method of well control. By optimizing the size of 114 mm perforating gun, the passage of pipe string can be increased, and pipe-sticking can be prevented. Key perforation tools such as three gun head protection primer and delay device are adopted to reduce the influence of mechanical and pressure loads. LWD tool is used to measure the formation gamma curve and position of casing isotopic markers in formation, instead of cable depth calibration technology, the accurate positioning of string can be quickly realized, and the perforation string structure can be optimized by LWD depth correction. A well control evaluation method suitable for ultra-deep wells has been developed. Completion fluid with low friction has been used. Compared with the conventional systems, the casing friction can be decreased by 30%, which ensured the smooth entry of perforation string. The field application results shows that this technology can obviously reduce the perforation risk of complex ultra-deep wells, achieve the goal of safe operation and accurate perforation, and provide technical support for tapping potential and increasing reserves and oil production in old oil fields.