英东油田短期注水开发套损机理研究  

Casing damage mechanism from short-term water injection development in the Yingdong Oilfield

作　　者：常智 侯冰[1,2] 汪涛 周波[3] CHANG Zhi;HOU Bing;WANG Tao;ZHOU Bo(College of Petroleum Engineering,China University of Petroleum-Beijing,Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum-Beijing,Beijing 102249,China;Research Institute of Petroleum Exploration and Development,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [3]中国石油勘探开发研究院有限公司,北京100083

出　　处：《石油科学通报》2020年第4期549-559,共11页Petroleum Science Bulletin

基　　金：国家自然科学基金项目(51874328,U1762215,U19B6003-05);中石油科技创新基金(2018D-5007-0307)联合资助。

摘　　要：英东油田采用油井转注水井二次采油时,短期内在疏松砂岩、泥岩交互层发生大量套管变形,导致注水开发效率低。为明确短期注水套损机理,基于井眼轨迹、测井资料、岩屑录井资料等钻井资料以及英东区块断层分布图,利用Petrel建立断层—岩性—射孔层位—套损位置关联的地质模型,分析了套损与注水时间、地层岩性、射孔位置和断层位置之间的关系,对比分析得出导致英东油田短期注水套损的主控因素为注水开发工艺和地层岩性。建立砂岩储层短期注水流固耦合有限元模型,对导致套损的主控因素进行模拟分析,研究了疏松砂岩储层短期注水后储层孔隙压力、地应力和位移等参数的变化,揭示了油井转注后短期注水导致套损的三种套损机理:(1)注水导致储层膨胀,形成沿井筒轴向的拉应力,使得套管被挤压变形,出现缩径、变形;(2)泥岩层遇水膨胀软化在砂泥岩交互层形成剪应力和沿井筒径向的压应力,使得套管同时受到剪切和挤压应力,出现错断、缩径和严重变形;(3)原出砂油井转注后,出砂层沉降,形成沿井筒轴向的压应力,使得套管出现扩径、变形。针对上述套损机理,提出了(1)注水层段不固井;(2)提高套管钢级、增加套管壁厚;(3)采用防砂完井工艺等套损防治对策,以保证井筒的长期完整性。In the Yingdong oilfield,a large number of casing deformations occurred in loose sandstone and interbedded mudstone soon after oil wells were turned to water injection wells,which resulted in low efficiency of water injection for secondary recovery.In order to clarify the casing damage mechanism caused by short-term water injection,based on drilling data such as borehole trajectory,logging data,cuttings logging data and fault distribution map of the Yingdong oilfield,a geological model of the correlation between fault-lithology and perforation-casing damage was established using Petrel software,and the relationship between casing damage and water injection time,stratigraphic lithology,perforation location and fault location was analyzed.The main controlling factors of casing damage are water injection technology and stratigraphic lithology.The flow-solid coupling finite element model of short-term water injection in a sandstone reservoir is established,which could simulate and analyze the main factors controlling casing damage.The variation of pore pressure,ground stress and displacement of the loose sandstone reservoir after short-term water injection was studied,and three mechanisms of casing damage caused by short-term water injection after oil well transfer were revealed:(1)Water injection causes the reservoir to expand and tensile stress arises along the casing axis,the casing would be deformed shown as casing diameter shrinkage and deformation;(2)Hydration of mudstone layers forms shear stress and compressive stress radially along the wellbore.At the interface of the sand and mudstone,the casing is subjected to shearing and extension at the same time,resulting in dislocation damage,diameter shrinkage and severe deformation;(3)After the original sand production well is converted into a water injection well,the sand production layer will be compacted forming compressive stress along the casing axis,the casing would be liable to diameter expansion and deformation phenomena.In view of the above casing damage me

关 键 词：短期注水 套损 砂泥岩界面 油井转注 流固耦合 

分 类 号：TE357.6[石油与天然气工程—油气田开发工程]