南海天然气水合物地层固井二界面胶结特性模拟  

Simulation on the second cementing interface bonding characteristics of nature gas hydrate formation in South China Sea

作　　者：王成文[1,2] 杨乐 薛毓铖 陈泽华 王鄂川 陈龙桥 李英杰 曹飞 邸建伟 WANG Chengwen;YANG Le;XUE Yucheng;CHEN Zehua;WANG Echuan;CHEN Longqiao;LI Yingjie;CAO Fei;DI Jianwei(Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)),Ministry of Education,Qingdao 266580,China;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China;Oil and Gas Technology Institute,PetroChina Changqing Oilfield Company,Xi'an 710018,China;CNPC Offshore Engineering Company Limited,Beijing 100028,China)

机构地区：[1]中国石油大学(华东)非常规油气开发教育部重点实验室,山东青岛266580 [2]中国石油大学(华东)石油工程学院,山东青岛266580 [3]中国石油长庆油田油气工艺研究院,陕西西安710018 [4]中国石油集团海洋工程有限公司,北京100028

出　　处：《中南大学学报（自然科学版）》2022年第3期933-941,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51991361,52074329);中国石油集团重大科技合作项目(ZD2019-184-003-004);长江学者创新团队发展计划(IRT_14R58)。

摘　　要：针对南海天然气水合物泥质粉砂地层松软且固结弱,固井胶结规律及界面损伤过程仍不清楚的问题,首先,制备南海天然气水合物模拟地层;其次,探讨水泥浆、地层类型和养护时间等对固井二界面胶结强度的影响规律;最后,利用内聚力模型模拟固井二界面黏性接触,并考虑水泥水化过程,建立固井二界面损伤分析模型,探究水合物固井二界面损伤规律。研究结果表明:水合物固井受泥质粉砂地层和低温影响,固井二界面胶结强度低且发展慢,水泥石与泥质粉砂地层难以形成有效胶结,固井封隔失效风险大,特别在低温、低密度水泥浆下更明显;固井候凝时间对固井封隔性能及井筒安全性的影响较大,水泥石需养护3 d以上,其强度、二界面胶结强度才会显著增加,固井封隔能力逐渐变好。为此,水合物固井在保证水泥浆低水化热前提下,水泥石还需要低温强度发展快而且强度高,保证固井界面封隔能力与水合物安全高效开采。The nature gas hydrate(NGH)argillaceous silt formation in the South China Sea is soft and weakly consolidated and the cementation rules and the interface damage process are still unclear.Aiming at the problems,firstly,the simulated formation of natural gas hydrate in the South China Sea was prepared.Secondly,the influence of cement slurry,formation type and curing time on the bonding strength of the second interface was discussed.Finally,the cohesive zone model was used to simulate the viscous contact of the second interface,the damage analysis model of the second interface was established considering the cement hydration process and the damage law of the second interface of NGH cementing was explored.The results show that hydrate cementing is affected by argillaceous silt formation and low temperature.The second interface has low cementing strength and slow development speed,and it is difficult to form effective cementing between cement stone and argillaceous silt formation.The fracture initiation degree of the second interface is large and the risk of cementing isolation failure is high,especially in the condition of low temperature and low density cement slurry.Cementing waiting time has a great influence on cementing isolation performance and wellbore safety.Cement stone needs to be cured for more than 3 d,its strength and the second interface bonding strength will increase significantly and cementing isolation ability gradually increases.Therefore,on the premise of ensuring the low hydration heat of cement slurry,the strength of cement stone at low temperature needs to develop fast,so as to ensure the sealing ability of cementing interface and the safe and efficient exploitation of NGH.

关 键 词：天然气水合物 固井 界面胶结强度 水泥石强度 黏结接触 界面损伤 

分 类 号：TE256[石油与天然气工程—油气井工程]