鄂尔多斯盆地深层煤岩气井储层坍塌及伤害主控因素研究  

Study on the Main Controlling Factors of Reservoir Collapse and Damage in Deep Coal Gas Wells in Ordos Basin

作　　者：阎荣辉[1] 王京光 何旺 李新强 陈春宇 李宏清 YAN Ronghui;WANG Jingguang;HE Wang;LI Xinqiang;CHEN Chunyu;LI Hongqing(Engineering Technology Management Department of PetroChina Changqing Oilfield Company,Xi′an,Shaanxi 710018,China;Drilling and Production Engineering Technology Research Institute,CNPC Chuanqing Drilling Engineering Co.,Ltd.,Xi′an,Shaanxi 710018,China)

机构地区：[1]中国石油长庆油田公司工程技术部 [2]中国石油川庆钻探工程有限公司钻采工程技术研究院

出　　处：《钻采工艺》2023年第6期8-13,共6页Drilling & Production Technology

基　　金：中国石油长庆油田分公司基金项目“深地煤岩气成藏理论与效益开发技术研究”(编号:2023Z-Z18)。

摘　　要：鄂尔多斯盆地深层煤岩气作为一种非常规资源,分布面积广、资源量大,是天然气增储的重要接替资源。由于煤岩强度低、裂缝发育易破碎,将导致煤岩掉块严重、起钻困难、频繁憋泵,因此深层煤层气钻进中井壁坍塌失稳、漏失成为安全钻进的主要限制因素。文章针对鄂尔多斯盆地本溪组煤岩井壁坍塌与伤害技术难题,开展了煤岩的物性、理化、力学性能评价等研究,明确了本溪组煤岩具有双孔隙结构,微孔占比平均56.5%,宏孔占比平均28.4%。煤岩中无机矿物成分主要以高岭石为主,含量为69.9%~88.4%,平均为79.7%;煤岩和煤矸均表现为弱亲水性和亲油性,煤岩样品在清水中的线性膨胀率为0.55%~0.87%,在水基钻井液中的膨胀率在0.10%以下,在油基钻井液中基本不膨胀。通过钻井液对煤岩渗透率伤害和空间CT评价实验表明,清水对煤岩渗透伤害率为74.7%;现场水基钻井液的渗透伤害率为89.9%;钻井液对平均孔隙度伤害率为22%,钻井液平均连通性伤害率为26%。基于室内实验结果分析,揭示出鄂尔多斯深层煤岩的坍塌伤害因素主要为煤层节理、微裂缝发育、胶结疏松、脆性大、应力敏感、非均质性强。钻开煤层后,外来流体沿裂缝渗入,引起分布在裂缝等处的黏土矿物水化溶胀和部分填充物溶解,弱化了煤岩的胶结强度,原有的力学破坏,煤层易碎裂垮塌。同时钻井液中固相颗粒对孔隙与裂隙的堵塞、钻井液固相侵入产生运移堵塞叠加造成了煤岩伤害。As a kind of unconventional resource,deep coal-rock in Ordos Basin has a wide distribution area and a large amount of resources,which is an important replacement resource for natural gas storage.Because of the low strength of coal and rock,the development of fracture is easy to break,which will lead to serious coal rock drop,frequent wellbore collapse and loss of pump hold-up have become the main limiting factors for safe drilling in horizontal section and high-efficiency development in later stage.In view of the technical problems of coal rock wall collapse and damage in Benxi Formation,the physical,chemical and mechanical properties of coal rock were evaluated,and clarified that the coal rock in the Benxi Formation has a dual-pore structure,which the average proportion of micropores is 56.5%,and the average proportion of macropores is 28.4%.The content of inorganic minerals in coal rock is mainly kaolinite(69.9%-88.4%,average 79.7%),coal rock and coal gangue are weak hydrophilicity and lipophilicity,the linear expansion rate in water of coal samples is 0.55%-0.87%,and it does not expand in drilling fluid.The permeability damage rate of drilling fluid to coal and rock is 74.7%,and the permeability damage rate of compound salt drilling fluid is 89.9%.The average porosity damage rate of drilling fluid is 22%,and the average connectivity damage rate of drilling fluid is 26%.Based on the results of laboratory experiments,it is revealed that the main factors of coal rock collapse damage in Benxi Formation are coal seam joints of Benxi Formation,development of micro-cracks,loose cementation,large brittleness,stress sensitivity and strong heterogeneity,the external fluid permeates along the fracture,causes the clay mineral hydration swelling and partial filling dissolution,weakens the coal rock′s cementation strength,original mechanical destruction,coal seam is easy to crack and collapse;The plugging effect of solid particles on pores and fissures in drilling fluid,the intrusion of drilling fluid and the migration an

关 键 词：煤岩气 鄂尔多斯盆地 本溪组 煤岩 井壁坍塌 钻井液伤害 

分 类 号：TE28[石油与天然气工程—油气井工程]