鲁迈拉南部油田RU45井溶洞性漏失堵漏技术

Severe Mud Loss Control in Well RU45 Rumaila Oilfield

RU45井是位于伊拉克鲁迈拉南部油田南部的1口疑难生产井,井深为3 410 m。鲁迈拉南部油田二开白云岩大溶洞恶性漏失现象普遍存在,地层压力异常,分上部Dammam层白云岩完全漏失、中部Umm Er Rad和Tayarat层硫水侵、下部Hartha层白云岩完全漏失3个地层压力段,一口井常伴有2种及其以上复杂情况;尤其南鲁迈拉油田下部Hartha层,一旦漏失发生,非常容易造成大溶洞漏失。在总结经验的基础上,RU45井采用先清水盲钻钻穿Dammam层,再实施承压堵漏,提高钻井液密度后钻穿硫水层,在Hartha层先后结合清水盲钻、水泥桥塞堵漏技术、下套管封隔器的一套快速堵漏工艺,减少了漏失量,缩短了二开大溶洞漏失完井时间,证明该井堵漏方案是鲁迈拉油田"上下漏,中间喷"白云岩大溶洞漏失最快速、最完整的技术方案。

Well RU45 with a depth of 3,410 m, is a problematic production well located in the south of Rumaila Oilfield, where severe mud losses into dolomite caves were frequently encountered. Abnormal formation pressures resulted in whole mud losses in the upper Dammam formation, sulphate water cut in the Umm Er Rad and Tayarat formations, and whole mud losses in the lower Hartha dolomite formation. Based on the experiences gained from offsite wells, it is decided that blind drilling with water be used to drill the Dammam formation, followed by strengthening the formations and sealing the fractures and vugs into which mud was lost. Mud weight was then increased to drill the Umm Er Rad and Tayarat formations. The Hartha formation was first drilled with water without controlling losses, then sealed the loss zones with cement plugs and casing packer. This technology greatly reduced the time spend dealing with mud losses, and was proved to be the fastest and completest technology for drilling formations with loss zones and blowout zones interlayered.