In this study, we perform several tests to develop a formula of glycerol-based drilling fluid that is suitable for shale formations with severe wellbore instability problems. Drilling fluids with varying combinations of nanosilica, glycerol, sodium carboxymethyl cellulose (Na-CMC), and xanthan gum (XG) in organic soil glycerol-based slurry are tested, and the effects of nanosilica on the swelling of shale samples and the lubricity of drilling fluids are also investigated to verify the feasibility of designed drilling fluids. The experimental investigations reveal that the values of apparent viscosity (AV), plastic viscosity (PV), and yield value (YP) of the optimal formulation meet the rheological parameters required for the drilling of shale formations. The AV and PV values of drilling fluid with 55:45 glycerol/water ratio are lower than those of drilling fluids with other glycerol/water ratios. A higher XG content means higher YP value in the experiment and 0.4% XG is suitable for the glycerol-based drilling fluid to prevent the collapse of the shale wellbore. There is a critical nanosilica content threshold (0.5%), and the filtration loss (FL) increases gradually when this threshold is exceeded due to the agglomeration of nanosilica. The nanosilica coated on clay particles in shales because of the formation of hydrogen bonds results in a decrease in permeability of shale formations. The swelling of shale through hydration is greatly reduced by 37% and the sticking coefficient of drilling fluid is reduced by 28% when 0.5% nanosilica is added. The addition of nanosilica to glycerol-based drilling fluid is significant to deal with the wellbore instability problems in troublesome shale formations.

在这项研究中，我们进行了一些测试，以开发一种适用于存在严重井眼失稳问题的页岩地层的甘油基钻井液配方。测试了在有机土壤甘油基浆液中具有纳米二氧化硅，甘油，羧甲基纤维素钠（Na-CMC）和黄原胶（XG）不同组合的钻井液，并且纳米二氧化硅对页岩样品的溶胀和润滑性有影响。还研究了钻井液，以验证设计钻井液的可行性。实验研究表明，最佳配方的表观粘度（AV），塑性粘度（PV）和屈服值（YP）的值满足钻探页岩地层所需的流变参数。55时钻井液的AV和PV值：45甘油/水比低于其他甘油/水比的钻井液。XG含量越高，实验中的YP值越高，0.4％XG适合于甘油基钻井液，以防止页岩井眼坍塌。有一个临界的纳米二氧化硅含量阈值（0.5％），并且由于纳米二氧化硅的团聚而超过该阈值时，过滤损失（FL）逐渐增加。由于氢键的形成而在页岩中的粘土颗粒上涂覆的纳米二氧化硅导致页岩地层的渗透性降低。添加0.5％的纳米二氧化硅后，通过水合作用使页岩溶胀大大降低了37％，钻井液的粘着系数降低了28％。