The Use of Circulating and Self-Filling Valves Facilitated Successful Run and Installation of a Liner in an Azeri Offshore Field
23 Apr 2015
In February 2015, the NewTech Services well completion team successfully run and installed a liner hanger in Azerbaijan’s offshore field operated by the State Oil Company of Azerbaijan (SOCAR) using circulating and self-filling valves. The specific technological and geotechnical conditions of the well drilling considerably complicated the liner running and installation process in the casing string. The adverse features included high-pressure zones (85 MPa); the presence of lost circulation zones; considerable depth of the liner hanger installation; narrow space between the liner and the borehole wall; high density drilling mud (up to 2.15 g/cm3– 2.20 g/cm3); and continuous well flushing in order to wash out gas slugs and cuttings. The liner hanger was modified so as to expand the space between the liner elements and the casing and use the liner in combination with the circulating valve. For the first time, a tool was used to mitigate the effect of swabbing, which in combination with the self-filling shoe and the circulating valve facilitated the lining run to the design depth without any complications and at a relatively high running speed. The proposed liner configuration proved beneficial in several respects: it reduced the surge and swab effects; ensured the string self-filling while running; equalized pressure in the tubing and annulus; reduced the liner running time; provided a back circulation option in the case of well flow; enabled well casing in lost circulation zones, where the use of conventional models with the ball or poppet-type back pressure valves could bring undesirable outcomes.