苏北盆地地层岩石特性及井壁坍塌周期研究  

Study on formation rock characteristics and borehole collapse period in northern Jiangsu Basin

作　　者：祁文莉 吴惠梅 谢贤东 楼一珊[1] 刘宏 QI Wenli;WU Huimei;XIE Xiandong;LOU Yishan;LIU Hong(Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas(Yangtze University),Wuhan,Hubei 430100,China;Research Institute of Petroleum Engineering,Sinopec Jiangsu Oilfield Company,Yangzhou,Jiangsu 225009,China)

机构地区：[1]油气钻采工程湖北省重点实验室(长江大学),湖北武汉430100 [2]中石化江苏油田分公司石油工程技术研究院,江苏扬州225009

出　　处：《中国海上油气》2024年第6期108-118,共11页China Offshore Oil and Gas

基　　金：国家自然科学基金项目“深水高温高压环境下钻井全过程井壁稳定评价方法(编号:51774050)”部分研究成果。

摘　　要：苏北盆地高邮凹陷花庄地区激活大量页岩油资源量,但页岩容易发生水化造成岩石强度降低引起井壁坍塌等复杂情况,从而需要确定该区块的井壁坍塌周期。以花庄区块阜宁组岩石为研究对象,系统开展了岩石微观结构、地层强度特性、吸水规律等研究,在实验研究的基础上建立坍塌压力预测模型,以此模型建立了本区块X井的安全密度窗口,分析了井斜角和方位角对该窗口的影响以及井壁坍塌周期。研究结果表明:①花庄地区阜宁组岩石整体结构较疏松,地层富含黏土矿物、石英和方解石等矿物元素,脆性矿物含量较高,总含量31.8%~43.8%,发育有方解石充填的张裂缝,黏土矿物以伊蒙混层和伊利石为主,伊蒙混层含量较高,水化膨胀性能较高。②在一定井斜角下,当方位角从最大水平主地应力方位向最小水平主地应力方位变化时,地层破裂压力逐渐增大,坍塌压力逐渐减小,安全密度窗口逐渐变大,当定向井的方位与最小水平主地应力的方位一致时,不易发生坍塌和井漏,钻井风险最小。③根据本文建立的坍塌压力预测模型计算,推荐阜宁组钻进时采用1.5 g/cm^(3)的复合有机盐聚合物钻井液,坍塌周期约51 d。本文研究成果对于研究地层安全密度窗口及井眼坍塌周期具有重要的指导意义。Huazhuang area in Gaoyou Sag of northern Jiangsu Basin activates a large amount of shale oil resources,but shale is prone to hydration,resulting in rock strength reduction and complex conditions such as borehole collapse.Therefore,it is necessary to determine the borehole collapse period in this block.The rock of Funing Formation in Huazhuang Block was taken as the research object,and the research on the microstructure of the rock,the strength characteristics of the formation,and the law of water absorption was systematically carried out.The collapse pressure prediction model was established on the basis of the experimental research,and then the safe density window of Well X in this block was established with this model.The influence of the well inclination angle and azimuthal angle on the window and the borehole collapse period was analyzed.The research findings indicate that:①The overall structure of the rock of Funing Formation in the Huazhuang area is loose,and the formation is rich in clay minerals,quartz,calcite,and other mineral elements.Brittle minerals constitute a high proportion,accounting for 31.8%-43.8%of the total content.Calcite-filled tensile cracks are developed,and clay minerals are predominantly illite-montmorillonite layer and illite,exhibiting high illite-montmorillonite layer content and significant hydration expansion properties.②Under a specific well inclination angle,as the azimuthal angle transitions from the maximum horizontal principal geostress azimuth to the minimum horizontal principal geostress azimuth,the formation rupture pressure gradually increases;collapse pressure gradually decreases,and the safe density window progressively widens.When the directional well azimuth is in alignment with the minimum horizontal principal geostress azimuth,the likelihood of collapse and well leakage diminishes,minimizing the drilling risk.③Based on the collapse pressure prediction model established in this study,it is recommended to employ a composite organic salt polymer drilling fluid wit

关 键 词：苏北盆地 岩石特性 泥页岩 安全密度窗口 坍塌周期 

分 类 号：TE21[石油与天然气工程—油气井工程]