Development And Mechanism Study On Amine Shale Inhibitor In Water-Based Drilling Fluid

With the increase of world energy demand and the development of drilling technology,the depth of drilling continues to increase and the conditions for drilling encounter more and more complex.Well wall stability caused by mud shale instability is often caused by safe,high quality,rapid and efficient drilling.It is very difficult,and it also puts forward higher requirements for drilling fluid technology.The anti-sloughing performance of traditional water-based drilling fluids needs to be fully improved.In recent years,the commercial exploitation of shale oil in the United States has greatly promoted the development of shale formation drilling technology.Among them,the developed high-performance polyamine water-based drilling fluid system not only solves the problem of safe drilling in shale formations,but also successfully replaces expensive and polluting oil-based drilling fluids with water-based drilling fluids.The key factor in the development of high-performance polyamine water-based drilling fluid systems is the study of shale hydration inhibitors.The development of polyamine inhibitors with excellent inhibitory performance and the establishment of a systematic method for analyzing the mechanism of action of polyamine inhibitors are of great significance to the development of polyamine high-performance water-based drilling fluids in China.Based on the homemade polyurethane shale inhibitor HGI,this article explores and optimizes the indoor synthesis route,and finally concludes that the ratio of the optimal monomer main agent A,main agent B,and auxiliary agent C is:2 to 2.5:1:0.05 The polymerization temperature is 150-160? and the polymerization time is 4.5-5.5 hours.The product was named polyamine-3 inhibitor,and its comprehensive performance evaluation revealed that it inhibited the mechanism of shale hydration and provided more technical solutions for borehole stability.Molecular structure characterization and inhibition experiments showed that the newly developed polyamine-3 is superior to traditional shale hydration inhibitors in inhibiting long-term inhibition at low concentrations,laying a foundation for the construction of high-performance water-based drilling fluid systems.The important material basis.With the help of the newly established mechanism analysis system:clay crystal layer spacing test,constant temperature deionized water adsorption,thermogravimetry analysis,combined with adsorption experiments,infrared spectroscopy,and Zeta potential tests,microscopically revealed polyamine-3 inhibitors The mechanism of action:non-ionic small molecules of polyamine strong inhibitors react with water after being partially protonated and positively charged,relying on electrostatic and hydrogen bonding to strongly adsorb on the negative surface of the clay,and exchanging clay hydration cations.In the process of dehydration,the electrostatic repulsion between the clay surface and the repulsion of the surface hydration film are weakened;the amine group in the polyamine molecule adsorbs on the clay surface at the same time,effectively binding adjacent clay sheets to form a close structure,preventing water into the clay layer.Therefore,polyamine-3 inhibits the hydration and dispersion of clay by inhibiting the hydration of the clay surface,preventing the hydration and dispersion of the clay;the polyamine molecules are strongly adsorbed on the clay surface,and the inhibition of the hydration effect of the shale can be maintained for a long period of time.The newly developed polyamine-strong inhibitors are used as the main treatment agents,and their effects on inhibiting the hydration of shale are comparable to those of oil-based drilling fluids.They include hot roll dispersion test,linear expansion test,particle size distribution test,and inhibition of bentonite pulping rate experiment.,It was confirmed that the polyamine-3 polyamine inhibitors exhibited excellent inhibition ability on the macroscopic level,and the polyamine-3 inhibitor on the mud page was explored from the microscopic and macroscopic perspectives by the newly established rock core compressive test and the bentonite slice microscopic scanning experiment.Rock mechanical properties.At the same time,the bio-toxicity test showed that polyamine-3 has low biological toxicity and is environmentally friendly.Pilot trials of polyamine-strong inhibitor polyamine-3 pilot production were conducted successfully.The results show that the newly developed polyamine inhibitors have good inhibition performance,simple production process and stable products,support providing safe and efficient drilling for shale gas horizontal wells.