Experimental Study On Morphology Control Of Horizontal Butt Well Cavity In Salt Cavern Gas Storage

When natural gas is in use,the insufficiency of seasonal peak shaving has become an important factor restricting the low-carbonization and environmental protection of primary energy consumption in China.The Opinions on Speeding up the Utilization of Natural Gas has made it clear that the working capacity of underground gas storage reached 14.8 billion cubic meters in 2020,in which salt cavern gas storage is an important part.Since the conventional method is time consuming,a new method is needed.Horizontal butt-well cavitation can improve the speed of cavity building,but its shape is still uncontrollable.The thesis establishes the experimental method of controlling the cavity shape of horizontal-butt wells through the experiment of corrosion rate of salt rock in Jintan salt cavern gas storage.Using real core experiment,the cavity shape and expansion rule of horizontal docking wells in salt cavern gas storage are observed directly.Finally,a set of feasible and large-scale visualization experimental method of simulating the cavity shape of horizontal butt-wells in the field is formed.The main research contents and results are as follows:(1)The thesis analyzes the factors influencing the corrosion rate of salt core in Jintan 1000 m horizon,and the experiments are carried out under the principle of controlling variables.The results show that the corrosion rate is most affected by the dip angle and the concentration distribution;the corrosion rate at 40? is 1.4 times of room temperature;the influence is little when the relative velocity of the corrosion surface is low;and the insoluble aggregation and deposition will reduce the corrosion rate.(2)Analyze the particle size distribution of insoluble to configure connection cement,then connect the multiple core models into a whole model without changing the dissolution properties.The thesis conducts an experimental method for controlling the cavity shape of horizontal butt wells,which for the first time visualizes the cavity shape and expansion law of horizontal butt wells.(3)Based on the core of Jintan Gas Storage Reservoir,the thesis conducts the horizontal butt well experiments through two-well convection method,step-back method and two-injection-one-drainage method.The results show that the fastest cavity-forming rate of step-back method is 6.05 times of that of single well water-solution method.The cavity-forming rate of two-well convection method and two-injection-one-drainage method is about 5.19 times of single well.The cavityforming of step-back method is the best,followed by two-injection-one-row method.The research results are expected to provide experimental basis for site horizontal butt-wells cavitation.