准噶尔南缘膏泥岩地层高密度防漏型油基钻井液研究

High Density and Leak Proof Oil Based Drilling Fluids for Mudstone Stratum in Southern Junggar

路宗羽 徐生江 叶成 孙晓瑞 马超 苏超

LU Zongyu XU Shengjiang YE Cheng SUN Xiaorui MAChao SU Chao

准噶尔盆地南缘地层含有大段膏泥岩和泥岩，具有高分散高膨胀的特点，且地层孔隙压力高、钻井液密度高、钻井液当量密度窗口窄，极易发生卡钻、井漏等井下复杂事故。针对这一问题，通过优选油基钻井液的组分和复合防漏材料获得了高密度防漏型油基钻井液体系。研究了油基钻井液的抗温抗盐性能、抗岩屑污染能力和防漏型油基钻井液的封堵防漏性能。结果表明，油基钻井液抗温抗盐性良好，在温度180℃和密度2.5 g/cm3的条件下，钻井液流变性和乳化性能稳定（破乳电压大于1000 V），可抗15%的CaSO4、12%的NaCl 和20%的CaCl2及10%岩屑污染。在油基钻井液中加入复合封堵剂（1%封堵剂FD-L+1%碳酸钙（600 目）+0.5%石墨粉）和3%油溶性膨胀堵漏剂（LCM）形成的高密度防漏型油基钻井液具有良好的封堵性能和防漏性能，封堵承压为7.75 MPa，在1~5 mm模拟裂宽下的堵漏承压为7.0 MPa。图1 表10 参16

The southern margin of Junggar Basin was characterized by a large contain of gypsum mudstone and mudstone which had a high dispersion and expansibility. Its high formation pressure required the use of high density drilling fluid with a narrow drilling fluid equivalent density window which was favorable to sticking and well leakage. In this investigation，a high density leak proof oil based drilling fluid was obtained by optimizing various ingredients as well as composite leak proof agents. The temperature，electrolytes and drilling cuttings tolerance of oil based drilling fluid was assessed and the sealing performance of formulated leak proof oil based drilling fluid was studied. The results showed that the formulated oil based drilling fluid had good temperature resistance and salt tolerance. Under the condition of 180℃ and 2.5 g/cm3 density，the rheology and emulsifying capacity of drilling fluid were stable. The emulsion-breaking voltage was bigger than 1000 V. Additionally，its rheological property and emulsifying capacity were not affected when exposed to 15% CaSO4，12% NaCl，20% CaCl2 and 10% drilling cuttings. When a composite plugging agent，including 1% bitumen FD-F，1% calcium carbonate（600 meshes）and 0.5% graphite powder，and 3% oil-soluble leak proof plugging agent（LCM）as the components of oil based drilling fluid，it had good plugging and leak proof performances.The sealing pressure of high density leak proof oil based drilling fluid was 7.75 MPa and the leak proof pressure at a width of 1—5 mm was 7.0 MPa.

10.19346/j.cnki.1000-4092.2018.01.001