国外Y区S25井堵漏技术

Control Lost Circulation in Well S25 of Block Y

国外Y区HOS区域南部边缘Pabdeh地层灰岩裂缝性发育,岩性为低强度白云岩,钻进施工过程中易发生漏失,漏层分布没有规律,漏失层位多且具有连续漏失特点,在漏速对密度敏感的井段难以堵漏,且裂缝性漏失地层的承压堵漏施工困难。针对上述难点,应用DL-A高温高压堵漏实验仪器,以2 mm圆孔模板,对不同配方桥堵剂进行了模拟堵漏实验,优选出了适合2 mm孔隙和裂缝性地层的桥堵剂,提出了该地区上部地层漏失以防为主,防堵结合的技术措施;中部地层采用低密度钻井液钻穿漏层,中下部地层采用随钻堵漏与承压堵漏相结合的钻井液技术,并优化堵漏浆配方以提高地层承压能力,该项技术在S25井应用中获得了良好的堵漏效果。

Mud losses were frequently encountered when drilling the Pabdeh, a low strength dolomite formation in the south edge of the HOS, Block Y in a country. Many mud loss zones are present and irregularly distributed, with lost circulation continually lasting for a long time. Rates of mud losses are sensitive to mud weight. To control the mud losses which had been difficult to stop during drilling operation, a bridge LCM formulation was developed through experiment on a DL-A HTHP LCM tester. This LCM formulation is suitable for controlling mud losses into 2 mm wide fractures. By analyzing the mud loss behavior in whole well drilling operation, it is recommended that when drilling the top formation, more attention should be paid to mud loss prevention, and use LCM mud to stop them if mud losses do occur. In the upper middle section of the well, low density should be used to drill through the thief zones. In the lower middle and lower section of the well, a combination of 'control mud losses while drilling' and 'control mud losses under pressure' techniques can be applied to stop mud losses or mitigate the negative effect of mud losses on drilling operation. These practices have been proved successful in the drilling operation of the Well S25.