摘要
鄂尔多斯盆地深煤层水平井钻井过程中易发生井壁坍塌等复杂事故,制约了钻井提速,增加了钻井施工难度。以井壁坍塌井为实例,对煤层割理及裂缝、力学特征进行了分析,研究表明:煤岩储层割理及裂缝发育、裂隙较小,但连通性强,钻井液易侵入;煤岩与煤层夹矸力学特征差异明显,煤岩一旦破碎,对夹矸的支撑就会大幅度降低,从而加剧夹矸垮塌,钻井液的固壁性和封堵性对预防煤层坍塌至关重要;并由2口典型井的测井解释对比印证了这一结论。优选了具有“核膜”结构的聚合物型纳米封堵防塌剂,以“硬暂堵+软封堵”为核心封堵理念,构建了一套深煤层防塌钻井液体系。室内实验表明,基浆中加入4%纳米封堵防塌剂后,中压滤失量从27 mL降至12 mL,深煤层防塌钻井液浸泡后的岩心抗压强度相比基浆提高了55.8%。钻井液体系现场试验井顺利完钻,未发生卡钻等事故。该研究为鄂尔多斯盆地深层煤层气的高效、安全开发提供了技术支持。
In response to the complex accidents such as wellbore collapse that are prone to frequently occur during the drilling process of deep coal seam horizontal wells in the Ordos Basin,which constrains the drilling speed and increases the difficulty in drilling operations.Based on the case studies of collapsed wells,the analysis of coal cleats,fractures,and mechanical properties,etc.was carried out,which reveals that the cleats and fractures development of coal rock reservoirs are small but strongly connected,enabling the drilling fluids invasion.The difference in mechanical properties between coal rock and coal seam gangue is significant,and the coal fragmentation dramatically reduces support for partings,intensifying their collapse.Thus,the wall-strengthening and plugging capability of drilling fluid are crucial for coal seam collapse prevention,which has been supported by the comparison of logging interpretations from two typical wells.A deep coal seam anti-collapse drilling fluid system was developed by optimizing the nano polymer sealing agent with a"nuclear membrane-like"structure as the anti collapse agent,based on the core sealing concept of"rigid temporary plugging+flexible sealing".Laboratory experiments have shown that after adding 4%nano anti-collapse plugging agent to the base slurry,the medium filtration loss decreased from 27 mL to 12 mL,and the compressive strength of the rock core soaked in deep coal seam anti-collapse drilling fluid increased by 55.8%compared to the base slurry.The field trials in test wells was successfully completed without any incidents such as pipe sticking.This research provides technical support for the efficient and safe development of coalbed methane in the Ordos Basin.
作者
耿学礼
敬倩
王乃兴
苏延辉
郑晓斌
冯雪松
李志臻
GENG Xueli;JING Qian;WANG Naixing;SU Yanhui;ZHENG Xiaobin;FENG Xuesong;LI Zhizhen(CNOOC Energy Tech-Drilling&Production Co.,Tianjin 300451,China;Downhole Technology Service Branch,CNPC Bohai Drilling Engineering Co.,Ltd.,Tianjin 300270,China)
出处
《石油钻采工艺》
北大核心
2025年第2期144-149,178,共7页
Oil Drilling & Production Technology
基金
中海油能源发展股份有限公司直属单位科研项目“临兴/神府区块深煤层自主化钻井液体系开发”(编号:GCJSXMHT-2412)。
关键词
鄂尔多斯盆地
深煤层
水平井
钻井液
井壁失稳
防塌
Ordos Basin
deep coal seam
horizontal well
drilling fluid
wellbore instability
anti-collapse
