正电胶钻井液增强煤层气钻井井壁稳定性试验研究

Experimental study on MMH drilling fluids enhancing coalbed methane drilling wellbore stability

为了解决煤层气钻井中普通存在的煤岩吸水膨胀、垮塌、掉块等技术难题,结合在水体系中煤的表面带负电荷特点,分别以有机正电胶MMH-1、无机正电胶MMH-2为主剂,配合增黏剂和降滤失剂进行试验,通过对钻井液流变性、滤失量、p H、膨胀量等基本性能指标的测试和优化,提出了2组适用于煤层气井钻井的抑制性正电胶钻井液体系。试验结果表明:2组钻井液配方性能优良,具有合理的黏度和切力,携带岩屑能力强,滤失量低,润滑性能良好;与5%KCl溶液相比,膨胀量仅为前者的1/4左右,能有效抑制煤岩膨胀,从而达到增强煤层气钻井井壁稳定性的目的。

In order to solve the common technical problems of coal water swelling,swapblock in coal gas drilling,combined with the characteristics of negative charge on the surface of coal in water system,organic MMH-1 and inorganic MMH-2 were used as the main agent separately and a series of experiments were carried out with viscosifier and fluid loss additive. According to test and optimize drilling fluid rheological properties,filtration loss,p H and other basic performance indicators,we proposed two kinds of MMH drilling fluid formulas for coalbed methane drilling. The experimental results showed that MMH drilling fluids had proper viscosity and shearing force,cutting carrying capacity,low fluid loss and good lubricating performance. Compared with 5% KCl solution,the swelling capacitiesof MMH drilling fluids were only one quarter which could effectively inhibit the expansion of coal rock and improve wellbore stability of coalbed methane wells.