辽河油田浅海钻井液技术

Shelf Sea Drilling Fluid Technology in Liaohe Oilfield

辽河油田滩海地区上部隔水管井段以流砂层为主,机械钻速高,环空岩屑量大,选用了正电胶钻井液;中下部地层富含以蒙脱石、伊蒙混层为主的泥岩,并且存在强坍塌应力及由沉积引起的超高压地层流体,存在井壁失稳问题;由于多个压力系统在同一裸眼段并存,油气水层相容、相近,极易发生井漏、井涌、井塌、卡钻等复杂事故,加之地层压力预测的局限,更增加了钻探难度,因此优选了海水KCl钻井液。在13口井的应用表明,海水KCl钻井液性能稳定,黏土容量限高,抗盐污染能力强,具有稳定井壁、井眼清洁、润滑防卡和保护油气层等特点,满足了辽河钻井的需要以及海洋环保的要求。

The formations of the top section in the shelf sea area in Liaohe oilfield are predominantly unconsolidated sand, and the rate of penetration (ROP) are generally high, leaving the annular spaces with laden drilled cuttings. MMH mud was chosen for this section. The intermediate and lower sections are characteristic of montmorillonite and illite/montmorillonite mixed layers, combined with high collapse stress and ultra high pressured formation fluids. Wellbore caving and sloughing were encountered in drilling these sections. Multi pressure systems coexisted in these sections, resulting in mud losses, well kick, and other drilling difficulties. Limit in pressure prediction made the situation worse. A seawater base mud with KCl was chosen for drilling the intermediate and lower sections. The engineered mud program had been applied in 13 wells and was successful.