Experiment And Numerical Simulation Of Construction Process Of Horizontal Storage In Salt Cavity

As an supporting project of West-East gas transmitting project—the construction of storage in salt rock is mainly aiming to meet the demand of an emergency gas supply in the case of pipeline damage or unbalanced adjustment of peak-load due to periodical climate changes. The storage caverns generally build in the deep salt domes in the foreign countries, the majority of storage is vertical. The salt deposits have geological characteristic of thin monolayer thickness and flabbiness interlayer in China. If we directly reference foreign construction methods in the construction of storage caverns, the storage cavern will pass through some of interlayer. In this way, not only the difficulty and complexity of storage construction has increased, the stability of the storage caverns in the later running will be greatly affected. Based on building the storage caverns in the bedded salt rock deposit by water-soluble building cavity, the paper combines the experiment and numerical simulation to preliminary study the construction of horizontal storage caverns in the salt deposits, the result provide a reference on the construction of horizontal storage caverns in the salt deposits. The main results are generalized as follows:(1) The dissolve law of the different location of rock salt core placed and the placement of water injection-outlet pipeline in experimental system were obtained through a series of dissolution experiment of Glauber’s salt rock; at the same time fitting the relation of the flow rate and the speed of dissolution in the concentration solution.(2) Numerical simulations were carried out on flow field in salt cavern at different stage of the construction of horizontal storage cavern, and the results show that:fluid formed jet when flow into the cavity through water injection pipeline; as the jet entrain the surrounding fluid, the width of jet continuously increase and transverse velocity distribution of the cavity becomes more evenly. Speed value is a linear relationship between boundary of the cavity and the water inlet at the stage of construction process; the speed value of cavity boundary firstly reduced and then tended to the same with the construction of cavity in the same water inlet velocity.(3) The concentration of the solution in the cavity gradually increase and then reach a stable value under the circumstances that the length horizontal cavities were same; with the water inlet velocity increased gradually, the location of the stability of concentration values in the cavity caverns went backwards, at the same time fitting the relationship between the location of the stability of concentration values and water inlet velocity at the initial stage of cavity, Therefore, under the circumstances that fixed length of horizontal cavity, we could determine an optimal injection flow made the concentration of dissolution reached a stable value at the outlet of cavities.(4) Numerical simulations were carried out on deformation and stress distribution in cavity of the surrounding rock at different stage of the construction of horizontal storage cavern, and the results show that:stress concentration in the surrounding rock of the cavity was less at the initial stage of horizontal cavity, as the construction of the cavity, there was great difference between the stress distribution of surrounding rock in the injection side and effluent side; in order to ensure to the stability of the horizontal cavity, we would exchange import and export well to maintain the balanced development of the caverns. In the different stage of the construction of horizontal storage, the deformation of cavity contracted toward the body cavity, the deformation of different parts of the cavity surrounding rock is different.