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开发川西新场上沙溪庙组气藏,钻遇地层为泥岩、砂砾岩、泥岩与砂岩互层,地层压力梯度从上至下由正常到压力过渡段,然后到异常高压。要求钻井液体系不但具有优良的防漏、防塌、防污染性能,而且能适应多种压力梯度情况,满足高密度要求。为克服表层的垮塌、缩径,采用高膨润土含量的钻井液开钻,并配合控制排量等措施;二开采用聚合物钻井液,根据气层压力调节钻井液密度,保持低粘度,适当放宽滤失量的限制范围,并利用固控系统清除钻屑、劣质膨润土;进入气层前,将聚合物钻井液转化为聚磺钻井液,并根据气层压力情况加重钻井液;对上沙溪庙组气层保护使用屏蔽暂堵技术。现场应用结果表明:该套钻井液体系能保证钻井工程顺利进行,有效地防止了坍塌、卡钻和井喷等复杂事故的发生,大大提高了钻井速度,缩短了钻井周期,而且在高密度情况下钻井液具有良好的流变性能和保护气层性能。
The Shaximian Formation gas reservoir on the new site in western Sichuan was developed. The strata encountered were interbedded with mudstone, glutenite, mudstone and sandstone. The stratigraphic pressure gradient from normal to pressure transition from top to bottom and then to abnormally high pressure. Requires drilling fluid system not only has excellent leak-proof, anti-collapse, anti-pollution performance, but also to adapt to a variety of pressure gradient conditions to meet the high density requirements. In order to overcome the collapsing and shrinking of the surface layer, the drilling fluid with high bentonite content is used for drilling and the displacement is controlled in coordination with the displacement. The second step is to use the polymer drilling fluid to adjust the drilling fluid density according to the gas pressure to keep the viscosity low, The limit of filtration range, and the use of solid control system to remove drill cuttings, inferior bentonite; before entering the gas reservoir, the polymer drilling fluid into polysulfide drilling fluid, and aggravate the drilling fluid according to the pressure of the gas reservoir; Temporary protection of the temple group gas shield temporary blocking technology. The field application results show that the drilling fluid system can ensure the smooth progress of drilling engineering, effectively prevent the occurrence of complex accidents such as collapse, stuck drilling and blowout, greatly increase the drilling speed and shorten the drilling cycle, and at high density Drilling fluid has good rheological properties and protective gas layer performance.