玛18井区水平井井壁失稳机理及强封堵钻井液技术研究

Well instability mechanism and strong plugging drilling fluid technology of horizontal well in Ma 18 well block

叶成 高世峰 鲁铁梅 屈沅治 戎克生 王常亮 任晗

YE Cheng GAO Shifeng LU Tiemei QU Yuanzhi RONG Kesheng WANG Changliang REN Han

中国石油新疆油田公司工程技术研究院 中国石油集团工程技术研究院有限公司 中国石油大庆钻探工程公司钻井一公司

Engineering Technology Research Institute, PetroChina Xinjiang Oilfield Company, Karamay 834000, Xinjiang , China CNPC Engineering Technology R & D Company limited, Beijing 102206, China No.1 Drilling Company of Daqing Drilling Engineering Company, Daqing 163411, Heilongjiang , China

为解决玛湖油田玛18井区致密油气藏水平井钻井过程中存在掉块、垮塌和缩径等井壁失稳问题，对克上组及百口泉组岩心进行了X射线衍射、扫描电镜、接触角、岩石力学实验，分析了该地层的理化性质、微观结构和力学性能。实验结果表明，黏土水化作用、岩石孔缝十分发育、钻井液侵入降低结构面强度是导致井壁失稳的主要原因。根据现场实际，采用油基钻井液增强对岩石的水化抑制效果。针对目的层岩石具有较多微纳米孔隙及裂缝的特征，研发出新型纳米封堵剂聚丙二醇接枝改性纳米SiO₂，粒径范围为17~197 nm，优选出复合型强封堵剂“3%氧化沥青+2%超细碳酸钙+2%纳米封堵剂”，构建了强封堵油基钻井液体系，该体系在120 ℃热滚16 h后，高温高压滤失量仅为1.2 mL，两次滚动回收率均大于97%，60 min后渗透性封堵滤失量为1.4 mL，具有良好的流变性、抑制性及封堵性。研究成果有效解决了玛18井区水平井井壁失稳难题，具有广阔的推广应用前景。

In the drilling process of horizontal well in tight reservoirs in Ma 18 well block of the Mahu Oilfield, wellbore instability happens such as block falling, collapse and hole shrinkage. To solve these problems, X-ray diffraction, scanning electron microscope (SEM), contact angle and rock mechanical experiments were conducted on the cores taken from Keshang Formation and Baikouquan Formation, and the physico-chemical properties, microstructures and mechanical properties of these formations were analyzed. It is experimentally indicated that the structural plane strength reduction caused by clay hydration, quite developed rock pores and fractures and drilling fluid invasion is the main reason for wellbore instability. Considering the actual situations on site, oil-based drilling fluid was adopted to enhance the inhibition to rock hydration. In view that there are more micro- and nano-pores and fractures in the rocks of the target layer, a new type of plugging agent was researched and developed, namely polypropylene glycol graft modified nano SiO, whose particle diameter ranges from 17 nm to 197 mn. The compound strong plugging agent of “3% oxidized asphalt+2% superfine calcium carbonate+2% nano plugging agent” was optimized, and the strong-plugging oil based drilling fluid system was prepared, whose high-temperature and high-pressure loss after 16 h of hot aging under 120℃ is only 1.2 mL, recovery rates after two hot agings are over 97%, and permeability plugging loss after 60 min is 1.4 mL, revealing its good rheological, inhibition and plugging behaviors. The research results effectively solve the wellbore instability problem of horizontal well in Ma 18 well block, and have promising promotion and application prospect.

10.13639/j.odpt.2023.01.006