地层渗流水对凝固过程固井水泥浆的侵扰机理  

Intrusion Mechanism of Seepage Water on the Cement Slurry During Setting Process

作　　者：刘开强[1] 于骏杰 王海平 张夏雨 金诚 张兴国[2] LIU Kaiqiang;YU Junjie;WANG Haiping;ZHANG Xiayu;JIN Cheng;ZHANG Xingguo(School of New Energy and Materials,Southwest Petroleum University,Chengdu 610500,China;National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Petrochina Chuanqing Drilling Engineering Co.,Ltd.,Changqing Well Reinforcement,Xi’an 710018,China)

机构地区：[1]西南石油大学新能源与材料学院,成都610500 [2]西南石油大学油气藏地质及开发工程全国重点实验室,成都610500 [3]中国石油集团川庆钻探工程有限公司长庆固井公司,西安710018

出　　处：《材料导报》2024年第24期126-131,共6页Materials Reports

基　　金：国家自然科学基金(52104007);全国重点实验室开放基金(PLN2023-35)。

摘　　要：针对老区调整井固井水泥浆受地层渗流水侵扰,降低水泥石层间封隔能力和油田开发效益的工程问题,以及渗流水对凝固过程水泥浆侵扰机理认识不清的科学问题,本研究工作建立了一套水泥浆凝固过程渗流水侵扰试验装置,表征了渗出水电导率、水泥石-岩芯的界面胶结状态;并利用低场核磁共振和电学方法,测定凝固过程水泥浆的孔径分布和孔隙连通性,综合分析渗流水对凝固过程水泥浆的侵扰形式和机理。结果表明:地层渗流水会破坏水泥石-岩芯界面结构,在迎水面水泥石-岩芯界面中段形成1~2 mm缝隙;同时,水泥浆在2.5 h至5.5 h的水化阶段中,离子快速溶入并渗出水,使其电导率由261.44μS/cm增至429.30μS/cm,与渗入水电导率相比增加了312.0%。凝固过程水泥浆的微观结构逐渐由“分散颗粒结构”发展为“凝胶网架结构”,导致其孔隙压力在数小时内迅速降为零,但该凝固阶段水泥浆内部仍存在大量毛细孔且孔隙连通性高达0.59~0.67,极易诱发渗流水侵入凝固过程水泥浆、置换其孔溶液,基于水泥“溶解-成核-沉淀”水化理论,该过程会破坏水泥浆的水化进程和设计性能,并最终降低水泥石层的间封隔能力和固井质量。There are two major problems inthe cementing engineering of the adjustment wells under seepage water intrusion,the first,in engineer,water intrusion reduces the zone isolation quality of hardened cement-sheath and oilfield development benefit,the second,in science,the intrusion mechanism of the seepage water on the cement slurry during setting process is unclear.Aiming to these,this work established a testing device for seepage water intrusion during cement slurry setting process to record the electrical conductivity of exudate water and bonding state between cement slurry and rock core interface,Low-field NMR and electrical methods were applied to measure the pore size distribution and pore connectivity of the cement slurry during setting process.And then,the intrusion mechanism of the seepage water on the cement slurry during setting process was analyzed.Experimental results showed that the seepage water destroyed the interface bond between hardened cement slurry and rock core to form a gap with 1—2 mm wideth.On the electrical conductivity of the seepage water,because the rapid dissolution of ions in cement slurry into exudate water from 2.5 h to 5.5 h of setting time,the exudate water’s electrical conductivity increased from 261.44μS/cm to 429.30μS/cm,increased by 312.0%compared with the water before INFILTRATION.During setting process,the microstructureof cement slurry developed from“dispersed particle structure”to“gel network structure”,which caused pore hydrostatic pressure to drop rapidly to zero within hours.With a hydrated time of 10 h,a large number of connected pores existed and the pore connectivity was 0.59—0.67 in the cement slurry,which was highly susceptible to seepage water intruding to replace its pore solution.Based on“dissolution-nucleation-precipitation”hydration theory,the hydration degree and designed properties of the cement slurry were destroyed.And then decreased the zone isolation quality of hardened cement-sheath and cementing quality.

关 键 词：调整井固井 水侵机理 地层渗流水 微观结构 电导率 水化行为 

分 类 号：TE122.3[石油与天然气工程—油气勘探]