Tian Yuexin, Liu Xiangjun, Luo Pingya, Huang Jinjun, Xiong Jian, Liang Lixi, Li Wenfei
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China.
ACS Omega. 2021 Jun 3;6(23):15448-15459. doi: 10.1021/acsomega.1c01936. eCollection 2021 Jun 15.
Here, we report a water-soluble shale inhibitor for inhibiting shale hydrate formation. The copolymer denoted as thermogravimetric analysis (TGA) was synthesized via triethanolamine, two maleic anhydrides, and glacial acetic acid. The infrared (IR) and gas chromatography (GC) results indicated that TGA is a low molecular weight polymer inhibitor (IR) and is the most commonly used method to identify compounds and molecular structures qualitatively. It is mainly used to study the molecular structure of organic substances and conduct qualitative and quantitative analyses of organic compounds. The main function of GC is for polymer molecular weight analysis. With the aid of shale rolling recovery experiments, particle size distribution experiments, triaxial stress experiment methods, bentonite slurry rate inhibition experiments, and thermogravimetric experiments to evaluate TGA inhibition characteristics, the inhibition effect of TGA is better than that of the traditional inorganic salt inhibitor KCl, polymer amine inhibitor UHIB, and organic cationic shale inhibitor NW-1. When the mass fraction is 0.2%, the cutting recovery rate increases from 18.3 to 94.1%. The compressive strength of the shale core after adding 1% TGA inhibitor is 177.9 MPa, which is close to the original core compressive strength of 186.5. The wet sodium montmorillonite crystal layer spacing after treatment with 0.5%, 1.5%, and 3% TGA aqueous solution is 1.38, 1.35, and 1.35 nm, respectively, and the sodium montmorillonite crystal layer spacing after diesel treatment is 1.34 nm, indicating that the inhibitory effect of TGA on sodium montmorillonite is equivalent to that of diesel and that TGA can effectively inhibit the hydration and dispersion of sodium montmorillonite. At the same time, the crystal layer spacing and the weight loss rate of sodium montmorillonite modified by TGA inhibitors did not change significantly after adsorption of deionized water, which proved that TGA inhibitors could be adsorbed in the crystal layer space of sodium montmorillonite to inhibit hydration and dispersion of sodium montmorillonite. Field test results show that TGA can significantly improve the inhibition performance of the field drilling fluid, and the effect is better than the strong conventional inhibition water-based drilling fluid system, which solves the problems of wellbore instability and considerable friction in horizontal shale sections and provides a new idea and method for efficient shale gas drilling.
在此，我们报道了一种用于抑制页岩水合物形成的水溶性页岩抑制剂。通过三乙醇胺、两种马来酸酐和冰醋酸合成了标记为热重分析（TGA）的共聚物。红外（IR）和气相色谱（GC）结果表明，TGA是一种低分子量聚合物抑制剂（IR），是定性鉴定化合物和分子结构最常用的方法。它主要用于研究有机物质的分子结构以及对有机化合物进行定性和定量分析。GC的主要功能是用于聚合物分子量分析。借助页岩滚动回收率实验、粒度分布实验、三轴应力实验方法、膨润土浆速率抑制实验和热重实验来评估TGA的抑制特性，TGA的抑制效果优于传统无机盐抑制剂KCl、聚合物胺抑制剂UHIB和有机阳离子页岩抑制剂NW - 1。当质量分数为0.2%时，岩屑回收率从18.3%提高到94.1%。添加1% TGA抑制剂后页岩岩心的抗压强度为177.9 MPa，接近原始岩心抗压强度186.5 MPa。用0.5%、1.5%和3% TGA水溶液处理后的钠基蒙脱石晶体层间距分别为1.38、1.35和1.35 nm，柴油处理后的钠基蒙脱石晶体层间距为1.34 nm，表明TGA对钠基蒙脱石的抑制效果与柴油相当，且TGA能有效抑制钠基蒙脱石的水化和分散。同时，经TGA抑制剂改性的钠基蒙脱石在吸附去离子水后，其晶体层间距和失重率变化不明显，这证明TGA抑制剂可吸附在钠基蒙脱石的晶体层空间中以抑制钠基蒙脱石的水化和分散。现场测试结果表明，TGA能显著提高现场钻井液的抑制性能，效果优于强常规抑制性水基钻井液体系，解决了水平页岩段井壁失稳和摩擦较大的问题，为高效页岩气钻井提供了新思路和方法。
