Chemical modification of barite for improving the performance of weighting materials for water-based drilling fluids  

作　　者：Li-Li Yang Ze-Yu Liu Shi-bo Wang Xian-Bo He Guan-Cheng Jiang Jie Zhang 

机构地区：[1]MOE Key Laboratory of Petroleum Engineering,State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Changping District,Beijing,102249,China [2]MOE Key CNPC Drilling Research Institute,Changping District,Beijing,102206,China

出　　处：《Petroleum Science》2024年第1期551-566,共16页石油科学（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant No.51991361);the foundation of China University of Petroleum(Beijing)(Grant No.2462021YXZZ002).

摘　　要：With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to reservoir damage and wellbore instability.In this paper,micronized barite(MB)was modified(mMB)by grafting with hydrophilic polymer onto the surface through the free radical polymerization to displace conventional API barite partly.The suspension stability of water-based drilling fluids(WBDFs)weighted with API barite:mMB=2:1 in 600 g was significantly enhanced compared with that with API barite/WBDFs,exhibiting the static sag factor within 0.54 and the whole stability index of 2.The viscosity and yield point reached the minimum,with a reduction of more than 40%compared with API barite only at the same density.Through multi-stage filling and dense accumulation of weighting materials and clays,filtration loss was decreased,mud cake quality was improved,and simultaneously it had great reservoir protection performance,and the permeability recovery rate reached 87%.In addition,it also effectively improved the lubricity of WBDFs.The sticking coefficient of mud cake was reduced by 53.4%,and the friction coefficient was 0.2603.Therefore,mMB can serve as a versatile additive to control the density,rheology,filtration,and stability of WBDFs weighted with API barite,thus regulating comprehensive performance and achieving reservoir protection capacity.This work opened up a new path for the productive drilling of extremely deep and intricate wells by providing an efficient method for managing the performance of high-density WBDFs.

关 键 词：Drilling fluids Weighting materials Filtration control Reservoir protection Stability property 

分 类 号：TE254[石油与天然气工程—油气井工程] TB383.1[一般工业技术—材料科学与工程]