煤层垮塌机理分析及钻井液防塌探讨  

Mechanism Analysis of Coalbed Caving and a Discussion about the Caving Prevention by Drilling Fluids

作　　者：陈在君[1] 刘顶运[1] 李登前[1] 

机构地区：[1]长庆石油勘探局工程技术研究院

出　　处：《钻井液与完井液》2007年第4期28-29,36,共3页Drilling Fluid & Completion Fluid

摘　　要：在长庆油田天然气水平井钻井过程中,处于大斜度井段的山西组、太原组及本溪组的多套煤层和炭质泥岩的稳定性极差,易发生垮塌。分析了煤系地层的垮塌机理,其完全不同于泥页岩地层,主要受煤岩的应力变化影响大;煤岩的弹性模量小、抗拉强度低,存在裂隙和巨大的比表面,对机械和物理化学的外力作用敏感。提出钻井液必须具有合理密度、强抑制、低滤失量、良好流变性和高润滑性等,并由此确定使用抑制性生物聚合物钻井液。该技术在现场进行了试验应用,满足了钻井工艺和稳定煤岩井壁的要求,确保了井眼稳定、起下钻畅通、电测和下套管顺利。In horizontal well drilling in Changqing area,the stability of the formations(such as the Shanxi Formation,Taiyuan Formation and Benxi Formation,in which coalbeds and carbonaceous mudstone were found) in the high angle section of the well,were very poor,and hole caving were encountered frequently.It was found that the caving of the coal beds are quite different than that of the shale/mudstooes,and is controlled primarily by the changes in stresses in the coal beds.Coal bed has a small modulus of elasticity and low tensile strength,and the existence of fractures and high surface area makes the coal bed very fragile to the action of mechanical and physical-chemical forces.The paper suggests that drilling fluid have a reasonable density,a strong inhibitive capacity,a low filtration rate,good rheology and lubricity.And an inhibitive biopolymer mud is presented for use in drilling the coal bed zones.Filed practices showed that this fluid technology was successful.

关 键 词：煤层 井眼稳定 水平井 抑制性钻井液 生物聚合物 

分 类 号：TE254.3[石油与天然气工程—油气井工程]