仿生绒囊钻井液煤层气钻井应用现状与发展前景

Application state and prospects of bionic fuzzy-ball drilling fluids for coalbed methane drilling

仿照细菌结构开发了含仿生绒囊的钻井液。CLY-A井欠平衡钻井表明,无需附加设备,调整钻井液密度0.8～1.0g/cm3即可循环;CLY-B井空气钻井表明,空气钻井过程中添加不同绒囊处理剂,可实现空气、雾、泡沫和绒囊不停钻转换钻井工作流体;DFS-C井防漏堵漏钻井表明,分压、耗压、撑压方式可控制钻井液漏失速度;FL-D分支井钻井表明,该钻井液具有低剪切速率下高黏度和高剪切速率下低黏度的特性,能够提高井眼清洁效率和机械钻速;J-E井不同压力系统共存于同一裸眼的井下复杂处理表明,该钻井液可以提高低压井段承压能力,满足动态窄密度窗口地层安全钻井。绒囊钻井液应加强绒囊结构微观研究、绒囊钻井液类型开发和低密度循环极限评价等,满足更多地层条件钻井需要。

The bionic fuzzy-ball drilling fluid was developed by imitating bacteria structure.Bionic Fuzzy-ball drilling fluid for underbalance drilling in well CLY-A shows the density of the fluid can range from 0.8 g/cm 3 to 1.0 g/cm 3 and it can be circulated without extra equipments.Compressed air drilling in well CLY-B proves that the different bionic fuzzy-ball additives varying drilling phases such as air,mist,foam and fuzzy-ball drilling fluid can be converted smoothly.Bionic fuzzy-ball drilling fluids for controlling and killing circulation loss in well DFS-C indicates it can control the leakage in forms of pressure reduced,pressure lost and pressure supported.The multi-branch drilling process in well FL-D shows both the cases of high viscosity with low shear rate and the low viscosity with high shear rate have good performance in cleaning wellbore and enhancing ROP.In well J-E,different formation pressure coefficients exist in the same open hole.The successful drilling proves it can improve the formation pressure bearing resistance in low-pressure section and help safe drilling in formations with narrow dynamic safe density window.Further study of bionic fuzzy-ball drilling fluid should focus on its microstructure,system type and circulation density,to satisfy more specific needs in drilling process.