| As China's emphasis on environmental protection continues to deepen,energy consumption structure is changing.The proportion of clean energy represented by natural gas in the energy consumption structure has been increasing year by year.However,the construction of gas pipelines and gas storage is seriously insufficient.The large-scale supply shortages in northern China in the winter of 2017 have seriously affected the production and life of the society.Faced with the severe gas supply situation,China has proposed relevant measures and requirements to deal with it,among which is the explicit requirement to speed up the construction of gas storage.As one of the important energy reserve sites,the salt cavern gas storage has many advantages.At present,the construction of salt caverns in China and abroad is mainly based on single wells,and there are many technical difficulties in salt cavern construction of double well.However,the construction of horizontal salt caverns will become an inevitable trend.Therefore,it is necessary to accelerate the research on the technology of horizontal wells,and the regularity of horizontal well morphology is the focus of research.This paper is based on the detection of the on-site shape of a certain level of horizontal wells and has carried out the following research work:(1)According to the characteristics of the horizontal well morphologies,the construction method of the horizontal well under different conditions was established;based on the on-site measurement of Huai'an X-Y horizontal salt cavern morphological data,combined with indoor simulation experiments and salt cavern leaching theory,The three-dimensional shape of the X-Y salt cavern is presented,and the morphological characteristics of the cavern are explained.At the same time,the cavern shape is verified from the mining volume,and the reliability of the constructed three-dimensional shape is further confirmed.(2)Because of the complexity of the construction site conditions of the reservoir and the long construction period,indoor simulation experiment is the most simple,fast,and feasible research method.Due to experiment needs,an indoor salt cavern leaching simulation experiment device was developed,and a pre-feasible study experiment was carried out to obtain the horizontal salt cavern shape under air-cushion-blocking conditions.The internal brine concentration field of the cavern was measured through the distribution point,and the distribution of the brine concentration in the cavern was obtained.(3)Based on the data of X-Y horizontal well,the main considerations are similarity in size and concentration of brines.Indoor simulation experiments were carried out using natural rock samples,and the three-dimensional morphology of the horizontal well with X-Y levels similar to those constructed was similarly obtained.The cavern shape verified the rationality of the three-dimensional shape of the constructed X-Y horizontal well.By measuring the internal brine concentration field of the cavern,the distribution law of the brine concentration was studied,and the formation reason of the cavern shape was explained in conjunction with brine concentration distribution.(4)Established the criterion for the stability of the horizontal salt cavern gas storage,and calculated the distribution cloud distribution,plastic zone distribution,and volume shrinkage ratio of the cavern under various working conditions through numerical simulation software,the cavern operation was determined.The minimum internal pressure is 8.0 MPa.According to the relevant regulations,the maximum internal pressure of the cavern operation is determined to be 22.0 MPa.The conclusion that the stability of the cavern between the maximum and minimum internal pressures for 30 years of operation is good.The stability of the cavern under the condition of sediment,and it is found that the sediment has obvious positive effect on the stability of the cavern. |
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