四川盆地抗CO_(2)污染高密度水基钻井液  

High-density water-based drilling fluid with resistance to CO_(2) contamination and its application to Sichuan Basin

作　　者：范劲 郭艳 李茂森 胡静 FAN Jin;GUO Yan;LI Maosen;HU Jing(Drilling Fluid Technology Service Company,CNPC Chuanqing Drilling Engineering Company Limited,Chengdu,Sichuan 610051,China)

机构地区：[1]中国石油集团川庆钻探工程有限公司钻井液技术服务公司,四川成都610051

出　　处：《天然气勘探与开发》2024年第4期99-105,共7页Natural Gas Exploration and Development

基　　金：中国石油集团川庆钻探工程有限公司科技重大专项课题(编号:CQXN-2021-07)。

摘　　要：随着勘探领域的日益扩大,四川盆地下川东地区、蓬莱、高石梯、磨溪等酸性气田高密度水基钻井液受CO_(2)污染问题日趋凸显,造成钻井液流变性能失控,增大了钻井过程中卡钻、井漏等钻井井下故障及复杂情况的风险。通过CO_(2)污染钻井液机理分析、抗污染处理剂优选及体系优化,形成了一套抗CO_(2)污染的高密度钻井液体系。研究结果证实:(1) CO_(2)污染水基钻井液轻度污染时黏土颗粒从粗分散转变为细分散,水化分散能力增强,而严重污染时CO_(3)^(2-)、HCO_(3)^(-)压缩双电层,钻井液胶体稳定性变差,体系性能急剧恶化;(2)基于抗污染处理剂优选,集成抗盐土、复合抑制、拓宽固相容量限研发的抗CO_(2)污染高密度水基钻井液体系在高浓度CO_(2)、CO_(3)^(2-)、HCO_(3)^(-)污染下,性能稳定、抗污染能力强。在四川盆地高XX井现场试验中,在遭遇井底CO_(2)污染时性能全程保持稳定,与同区块邻井相比平均机械钻速提高5.6%~23.8%,钻井液处理方量降低64%以上。With exploration advancement in Sichuan Basin,one problem that water-based drilling fluid with high density is contaminated by CO_(2) is increasingly prominent in some sour gas blocks or fields(e.g.eastern basin,as well as Penglai,Gaoshiti,and Moxi fields),which causes the fluid’s rheology out of control to further increase downhole accidents and complexities,such as pipe sticking and lost circulation.Thus,a system of high-density drilling fluid with resistance to CO_(2) contamination has been developed by analyzing contamination mechanisms and selecting appropriate anti-pollution agents.Results show that(i)slight contamination refers that clay particles transit from coarse to fine dispersion,resulting in enhanced hydration and dispersion,while severe one implies CO_(3)^(2-)and HCO_(3)^(-)compress double layers,making the fluid’s colloid stability get worse and the system performance take a sharp turn for the worse;and(ii)with anti saline soil,compounding inhibition,and expanding solid phase content,this developed system exhibits stable performance and strong anti-pollution under the contamination of CO_(2),CO_(3)^(2-)and HCO_(3)^(-)with high concentration.Its application to GaoXX well in Sichuan Basin demonstrates stable performance consistently when CO_(2) contamination at the bottomhole,with the average ROP enhanced by 5.6%to 23.8%and the drilling-fluid volume reduced by more than 64%as compared with adjacent wells in the same block.

关 键 词：CO_(2)污染 高密度 水基钻井液 污染机理 四川盆地 

分 类 号：TE254[石油与天然气工程—油气井工程]