基于疏水型纳米二氧化硅的页岩气盐水钻井液  

Study on Saltwater Drilling Fluid Treated with Hydrophobic Nano SiO_2

作　　者：应春业 李新亮[2] 杨现禹 蔡记华[1] 段隆臣[1] 

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074 [2]中国石油大学(北京)石油工程学院,北京100083

出　　处：《钻井液与完井液》2016年第4期41-46,共6页Drilling Fluid & Completion Fluid

基　　金：国家自然科学基金项目"纳米架桥材料在低孔低渗煤层气藏钻完井过程中的暂堵机理研究"(41072111);中国石油科技创新基金项目"纳米材料增强页岩气水平井井壁稳定性的作用机理研究"(2014D-5006-0308);湖北省自然科学基金重点项目"水基钻井液增强页岩气水平井井壁稳定性的理论与方法"(2015CFA135);国家级大学生创新创业训练计划项目"基于纳米材料的页岩气水平井抗高温盐水钻井液体系研发"(201410491046)

摘　　要：由于页岩地层层理和裂缝发育，且具有水化性，因此在钻井作业中常面临井壁稳定、降摩减阻、岩屑清除等难题。为此，优选了疏水型纳米二氧化硅作为泥页岩封堵剂，以减少水分侵入，抑制泥页岩水化膨胀。通过钻井液常规性能测试、扫描电镜分析，评价了不同纳米二氧化硅对盐水钻井液的影响。结果表明：①疏水型纳米二氧化硅具强疏水性与强吸附性，能吸附在泥饼上，形成纳米颗粒隔水层，有效降低滤失量；②纳米二氧化硅加量为1％～3％时，疏水型固体纳米二氧化硅可使钻井液滤失量降低48．7％，疏水型纳米二氧化硅分散液可使钻井液滤失量降低41．67％，但固体颗粒易团聚，易失去纳米颗粒特性；③在180℃、NaCl含量25％、分散液加量3％条件下，钻井液滤失量为8．2mL；在室温～180℃下，钻井液水活度稳定在0．815～0．849，页岩膨胀率在4％左右，具有较强的抑制性；钻井液的润滑系数稳定在0．11～0．12，润滑性能较好。综合考虑滤失量、稳定性和性价比等因素，选定基于3％疏水型纳米二氧化硅分散液和25％NaCl的钻井液体系为最优配方。Shale drilling is always faced with these problems such as borehole wall instability, high friction and drag and borehole cleaning etc. resulted from shales with developed beddings and fractures, and shale hydration. A hydrophobic nano SiO2 was selected as a plugging agent used to reduce water invasion into the fractures in shales, and hence to inhibit the shales from hydrating and swelling. The effects of different nano SiO2 on brine drilling fluids have been studied through laboratory experiments on regular mud property and SEM analyses. It was found that （1） the hydrophobic SiO2 has strong hydrophobicity and adsorbability; the SiO2 powder can form a barrier to water invasion by adsorbing onto mud cakes, thereby effectively reduces the filtration rate. （2） the solid hydrophobic SiO2 at 1% - 3% reduces the filter loss by 48.7%, while a hydrophobic SiO2 suspensions reduces the filter loss by 41.67%, but the solid hydrophobic SiO2 tends to agglomerate, thus losing the nano features.（3） at 180 ℃, drilling fluid treated with 25% NaCl and 3% hydrophobic SiO2 suspensions has filter loss of 8.2 mL. At room temperature to 180 ℃, the water activity of drilling fluids treated with the hydrophobic SiO2 is 0.815 - 0.849, and the percent swelling of shale cores is about 4%, meaning that the SiO2 has strong inhibitive capacity. The coefficient of friction of drilling fluids treated with the hydrophobic SiO2 is 0.11 - 0.12, meaning the SiO2 treated drilling fluids have good lubricity. With all factors such as filter loss, stability and cost efficiency considered, a drilling fluid containing 3% hydrophobic SiO2 suspension and 25% NaCl is the optimum formulation.

关 键 词：页岩气 盐水钻井液 疏水型纳米二氧化硅 封堵剂 

分 类 号：TE254.3[石油与天然气工程—油气井工程]