In this paper was study the wellbore instability caused by hydration of shale formation during drilling is a major problem in drilling engineering. A polyhydroxy-alkanolamine was synthesized, and the shale inhibition performance was evaluated by anti-swelling test, linear swelling test, wash-durable test and bentonite hydration and dispersion experiment. The shale inhibition mechanism of polyhydroxy-alkanolamine was studied by Fourier transform infrared spectroscopy (FTIR), particle size distribution, Zeta potential, Thermal analysis and Scanning electron microscopy (SEM). The main results show that the use of polyhydroxy-alkanolamine (EGP-2) can result in a relatively lower linear swelling rate of bentonite, and the linear swelling rate of 0.3% EGP-2 was 26.98%, which is stronger compared with 4% KCl. The anti-swelling rate of 0.3% EGP-2 was 43.54%, the shrinkage swelling rate of 0.3% EGP-2 was 34.62%. Results show that EGP-2 may permeate and adsorb on the bentonite surface. The rolling recovery rate of easily hydrated shale was high as 79.36%, which greatly reduces the dispersion ability of water to easily hydrated shale. The results of this study can be used to maintain the stability of the wellbore, which is conducive to related research.

In this work, the quaternary ammonium salt small molecule inhibitors with melamine and sodium chloroacetate as raw materials was synthesized and it has certain inhibition on the hydration swelling of bentonite. Through linear swelling test, mud ball test and drilling fluid performance evaluation, its inhibition performance in clay is evaluated. The results show that the linear swelling rate of bentonite in 0.5% MAA-3 solution is 57.28% at 90 min, which is similar to that in 4.0% KCl solution.

Due to the strong inhibition of drilling fluid, many polymer fluid loss additives can not play their role. Therefore, it is necessary to develop some water loss reducing materials that can withstand the strong inhibition environment. In this paper, the surface of asbestos fiber was modified and treated by indoor experiments. The physical and chemical properties of the obtained drilling fluid treatment samples were evaluated to optimize the appropriate amount of reagents used for surface treatment of asbestos. Subsequently, the drilling fluid performance of the obtained treatment agent samples were evaluated at different temperatures to analyze the effect of temperature on the drilling fluid performance. The surface of asbestos fiber was modified by adsorbed cationic surfactant CTAC which better solved the problem of entanglement of asbestos fiber in drilling fluid. The mechanism of the action of the surface of asbestos fiber was analyzed by scanning electron microscope observation experiments. Subsequently, different amounts of modified asbestos fiber was added to the drilling fluid and the performance of drilling fluid was evaluated at different temperatures. The experimental results showed that the modified asbestos fiber reduced the filtration loss of drilling fluid and still maintained good filtration loss reduction effect at 200°C.

Due to the strong inhibition of drilling fluid, many polymer fluid loss additives can not play their role. Therefore, it is necessary to develop some water loss reducing materials that can withstand the strong inhibition environment. In this paper, the surface of asbestos fiber was modified and treated by indoor experiments. The physical and chemical properties of the obtained drilling fluid treatment samples were evaluated to optimize the appropriate amount of reagents used for surface treatment of asbestos. Subsequently, the drilling fluid performance of the obtained treatment agent samples were evaluated at different temperatures to analyze the effect of temperature on the drilling fluid performance. The surface of asbestos fiber was modified by adsorbed cationic surfactant CTAC which better solved the problem of entanglement of asbestos fiber in drilling fluid. The mechanism of the action of the surface of asbestos fiber was analyzed by scanning electron microscope observation experiments. Subsequently, different amounts of modified asbestos fiber was added to the drilling fluid and the performance of drilling fluid was evaluated at different temperatures. The experimental results showed that the modified asbestos fiber reduced the filtration loss of drilling fluid and still maintained good filtration loss reduction effect at 200°C.