相国寺地下储气库钻井难点及技术对策

DRILLING CHALLENGES AND TECHNICAL SOLUTIONS FOR XIANGGUOSI UNDERGROUND GAS STOREROOM

相国寺储气库是我国西南地区第一个开建的储气库,是典型的枯竭型碳酸盐岩油气藏。储气库具有运行周期长,注采井要求强注强采,周期循环等特殊要求,因此对注采井井筒完整性要求非常高。相国寺储气库除对注采井井筒完整性要求高外,其构造本身目前有多个产层压力系数低于 1. 0; 出露地层老,极易井漏; 属典型的高陡构造,自然井斜规律性强; 井漏与垮塌并存; 构造内煤矿、石膏矿多,属风景区和自然保护区,对安全钻井带来极大难度。文章针对相国寺储气库钻井难点,提出了优化井身结构设计、优选气体钻井方式、合理部署丛式井组和优化井眼轨迹、采用管外封隔器和柔性水泥浆体系、采用防砂筛管完井等技术对策。该储气库的建成,将为西南地区储气库建设起到非常重要的示范作用,并提供很好的技术支撑。

Xiangguosi underground gas storeroom is the first building underground gas storeroom in Southwestern area in China. It is a typical carbonate gas reservoir. The gas storeroom would work for long time,and the injection wells would be needed for powerful injection and production,and would make a circulation periodically,and other special requirements would be wanted,which needs exact injection hole integrality. In addition to well geometry integrality,currently,there are several different pressure gradient,which are less than 1.0,shallow formation is old,but easy to cause loss,typical high deviated stratum,strong building capacity while rotary drilling,loss and collapse together while drilling,coal and gypsum,the gas field is in the beauty spot and natural protecting zone,all these factors would result in extreme difficulties in safe drilling. Compared with drilling challenges in the reservoir,this paper put forward solutions,which included optimal well geometry,optimal gas drilling methods,reasonable cluster arrangement,optimal well trajectory,external completion packers and flex slurry,screens preventing sands in completion. As soon as this gas reservoir is set up,it must play very important model role in reservoir construction in southwestern area,and provide good technical support.