川东北地区抗高温超高密度钻井液研究

A Study on the High Temperature High Density Drilling Fluids for Use in Northeast Sichuan.

川东北地区海相碳酸盐岩高含硫气藏存在硫化氢含量高、盐膏侵严重、易发生井漏、井壁失稳、井底温度高、压力大等难点,通过对抗高温处理剂、加重剂、膨润土限量进行优选,形成了满足川东北地区深井超深井钻井要求的抗高温超高密度复合金属离子聚磺钻井液。该体系抗温可达180℃,可控密度达2.70 g/cm3(储备钻井液密度达3.0 g/cm3),具有良好的高温稳定性、润滑性和抑制性能,具有较好的抗污染能力,抗NaCl达10%,抗Ca2+达2 000 mg/L,抗岩屑达20%;使用复合储层保护剂后,屏蔽暂堵率在99.5%以上,压力返排恢复率超过80%,酸化返排恢复率达到200%左右,能有效地保护油气储层。在河坝1井和金溪1井的现场应用结果表明,该体系具有良好的高温稳定性、流变性能、润滑性能、抑制性能和抗污染性能,满足了川东北地区高温超高密度压井修井液和钻井完井液的各项要求,且储层保护效果良好。

A high temperature high density polymer drilling fluid was designed for use in deep and ultra deep wells in northeast Sichuan, where the carbonate formations contain high concentration of hydrogen sulfide, and salt/gypsum contamination, mud loss, borehole sloughing, high temperature and high pressure were frequently encountered. This drilling fluid is stable at temperature of 180 ℃, and density of 2.7 g/cm3. At salt concentration of 10%, or calcium concentration of 2,000 mg/L, or cuttings concentration of 20%, this fluid still retained its good rheology and lubricity. Permeability recovery was greater than 80% back flowed under pressure, and 200% back flowed after acidification stimulation. Good results were obtained in well Heba-1 and Jinxi-1 using this drilling fluid.