肯基亚克盐下油田的钻井液技术研究

APPLICATION OF DRILLING FLUID TECHNOLOGY IN KENKYAK OILFIELD

肯基亚克盐下油田的主要地质特点是 :下二叠系盐层发育 ,在盐丘主体部位钻井 ,盐层厚度可达 30 0 0m ;石炭系灰岩油层孔隙压力系数高达 1.90～ 1.94 ,钻井液安全密度窗口窄 ,溢漏同层 ,极易出现先漏后喷的复杂局面。因地质条件引发的复杂事故严重制约了肯基亚克盐下油田的钻井工作。针对肯基亚克盐下油田复杂地质条件 ,研究开发了钻井液体系及配套技术 ,经 2 0 0 2、2 0 0 3年肯基亚克盐下油田 9口井的应用 ,钻井复杂事故率大大降低 ,钻井速度显著提高 ,原油产量大幅上升 ,钻井成功率达 10 0 % 。

The reservoirs in Kenkyak oilfield are deep and high pressured reservoirs with complicated geological condition. The main characteristics of formation are :the salt formation is so developed that may reach about to 3000 meter thickness in Permian above main area of salt dome .Reservoir pore pressure coefficient of Carboniferous system is up to 1.90-1.94. Because carbonate rock which is the main reservoir developed many cracks that caused not only mud loss but also well kicked, and the safety density window of drilling fluid was narrow, first lost circulation then well blowout was easily happened. In the past thirty years ,many drilling accidents such as well blowout, mud loss, well slough, stick pipe were often happened .The obvious characteristic of drilling engineering was to have many accidents ,slowly pace and lower successful rate .It seriously influenced drilling works that many drilling accident happened by the complicated geological condition causing .Based on these characteristics of formation ,a series drilling fluid technologies for preventing accidents were developed by South-west petroleum institute(SWPI) ,and then used in 9 wells in Kenkyak oilfield successfully during 2002 and 2003 year. By adopting these technologies ,the remarkable application effects have been achieved ,such as the drilling accident rate greatly reduce, the drilling pace obviously improved, drilling successful rate was up to 100%.