Research and application of unconventional well control safety technology in underground operation of constant volume carbonate reservoir

In Tarim Oilfield, carbonate fractures-vuggy reservoirs are mainly cave-type and fissures-vuggy reservoirs, which are easy to produce with high yield but difficult to maintain. They have high initial production and large natural decline, generally ranging from 30% to 50% per year in the early stage. Downhole operations of these reservoirs are characterized by deep burial, low pressure coefficient, hydrogen sulfide content, shaft wall collapse, and frequent conversion of spills and losses. Faced with such problems as high risk of well control, sand blocking in wellbore, easy formation of trap pressure, difficult site management, and inability to conventional well killing, combined with the characteristics of constant volume carbonate reservoir, The research on unconventional well control safety technology in the underground operation of constant volume carbonate reservoir is carried out with the focus on “keeping wellbore smooth, controllable and close wellhead, supporting equipment and technology, and surface emergency support”, which provides reference for the subsequent underground operation of constant volume carbonate reservoir.