奎河1井超高压地层控压钻井优化设计与试验

OPTIMIZATION AND TEST OF MPD IN ULTRAHIGH PRESSURE FORMATION OF WELL KUIHE 1

奎河1井目的层连木沁组属于超高压、窄安全密度窗口地层,若采用常规钻井技术,按井控规定,钻井液密度设计将达2.78 g/cm^3,钻井液的性能控制难度较大,同时,钻进中井底循环当量密度将超过漏失压力窗口,易发生漏喷复杂。针对此类超高压地层,提出了一种利于井控安全的控压钻井设计方法,并对奎河1井方案进行了优化设计,结果表明,钻井液密度为2.60 g/cm^3,井口回压0.83 MPa,井底当量钻井液密度在2.78 g/cm^3,停泵时井口回压控制在4.18 MPa;优选出采用冻胶阀封隔裸眼井段,冻胶阀最小抗压差强度5.54 MPa,冻胶阀最优长度为533.82 m。奎河1井现场试验表明,井段3 550~3 680 m,控压钻进、停泵补压、冻胶阀起下钻与优化设计结果相符,解决了漏喷复杂情况,并顺利钻至设计目标。奎河1井控压钻井试验成功将为国内外其它超高压地层的控压钻井技术实施提供有效的技术支持。

The target zone of Well Kuihe-1 was Fm. LianMuQ in,with ultra-high pressure and narrow safe density window. If the conventional drilling technology to be adopted,according to Well control regulations,the designed drilling fluid density would reach 2. 78 g/cm^3,which would lead to very hard drilling fluid performance control. And the equivalent circulating density at the well bottom would exceed the well loss pressure window during drilling,causing well loss and blowouts.For this type of ultrahigh pressure formation,MPD design was proposed,which was helpful for well control and safety. The drilling plan for Well KeiHe 1 was then optimized. The results showed that the drilling fluid density was 2. 60 g/cm^3,the wellhead back pressure was 0. 83 MPa,the well bottom equivalent drilling fluid density was 2. 78g/cm^3,and the wellhead back pressure was controlled at 4. 18 MPa when the pump stopped. The frozen gel valve was optimized to seal the open hole section,it minimum pressure differential was 5. 54 MPa,the optimum length was 533. 82 m,The field test onW ell KuiH e 1showed MPD, pressure compensation at pump stop and the freezing valve tripping were consistent with the optimization design,the complicated blowout or loss was controlled,and the well was successfully drilled designed MD. The successful test on Well KH1 may provide an effective technical support for application of MPD technology at other ultrahigh pressure strata at home and abroad.