超低渗透钻井液完井液技术研究

Study on ultra-low permeability drilling/completion fluid.

介绍了零滤失井眼稳定剂及超低渗透钻井液完井液的组成。在水基、油基钻井液中加入一定量的零滤失井眼稳定剂可以形成超低渗透钻井液。对加入一定量零滤失井眼稳定剂钻井液的API滤失量、高温高压滤失量、砂床滤失量、高温高压砂床滤失量、岩心滤失量、岩心承压能力、封堵裂缝效果和岩心渗透率恢复值的变化进行了评价。实验结果表明,超低渗透钻井液的砂床滤失量不是时间平方根的函数,与API滤失量没有对应关系;超低渗透钻井液对不同孔隙的砂床、岩心和裂缝具有很好的封堵能力,可以实现零滤失;零滤失井眼稳定剂可以防漏堵漏;通过增强内泥饼封堵强度大幅度提高了岩心承压能力;能有效保护储层,岩心渗透率恢复值大于95%。

In this paper, a zero-filtration hole stabilizing agent and composition of ultra-low permeability drilling fluid are presented. The fluid of ultra-low filtration comes into being when some zero-filtration hole stabilizing agent is added into the water-base or oil-base drilling fluid. Such items as API filtration, HTHP filtration, sand-bed filtration, HTHP sand-bed filtration, core filtration, core bearing ability, fissure openings plugging ability and permeability recovery of the fluid were evaluated in lab. Results illustrates that the sand-bed filtrate value is not a function of the square root of time, and there is no correlation between API filtrate value and the sand-bed ones; the ultra-low permeability drilling/completion fluid has characteristic of sealing formations of different pore size distribution with no filtration; and the zero-filtration hole stabilizing agent may be used to stop fluid loss. By enhancing the strength of the internal mud cake, improving the core bearing ability, the fluid can protect oil/gas reservoir effectively with permeability recovery of more than 95%.