Research On Identification Of Suitable Exploitation Area And Optimization Of Exploitation And Reinjection Mode For Porous Medium Reservoir

As a green and low-carbon renewable energy,the reasonable development and utilization of geothermal energy can provide strong support for the green and low-carbon transformation of energy and the realization of carbon peak and carbon neutral goals.With the development of drilling technology,geothermal resources have been widely developed and utilized.However,in the process of exploitation of geothermal resources,there are many problems,such as the selection of exploitation location is not definite enough,the geothermal water level and the exploitation temperature drop rapidly.In view of the development and utilization of porous medium reservoir in Linqing City,Shandong Province,through the engineering background,domestic and foreign research status,and comprehensively using the methods of theoretical analysis,field monitoring and experimental testing,GIS spatial analysis and numerical simulation,the suitable areas for the exploitation of thermal reservoir in the research area were identified,the exploitation and irrigation patterns were optimized,the main research contents are as follows:(1)The key index factors for identifying suitable areas for thermal reservoir exploitation are determined.The selection steps and evaluation principle of suitable area for thermal reservoir exploitation are proposed.Combined with GIS spatial analysis technology,the index factor database for identifying the suitable area of thermal storage exploitation in Linqing City is established.The weight of the index factors is calculated by CRITIC weight method.The TOPSIS method is used to determine the suitable area for thermal reservoir exploitation in the research area.(2)The multi field coupled three-dimensional numerical model is established for the suitable area of thermal storage exploitation.The numerical model is used to analyze and calculate the influence of different well spacing on geothermal water level and exploitation temperature.The influence of three multi-well layout schemes of "one exploitation and two irrigation","two exploitation and one irrigation" and "two exploitation and two irrigation" on geothermal water level and exploitation temperature is studied.(3)Based on the orthogonal design method,nine groups of orthogonal test schemes were designed,and the sensitivity analysis of thermal storage,exploitation and irrigation performance was carried out for the exploitation of geothermal water,the reinjection rate of geothermal tail water and the reinjection temperature of tail water.The range analysis method and variance analysis method are used to determine the main factors affecting the variation of geothermal water level and exploitation temperature.Heterogeneous thermal reservoir with normal distribution of permeability and porosity are established respectively.and research on the influence of different variances on the exploitation temperature of thermal reservoir is carried out.The results show that the decline of geothermal water level is most affected by the recharge rate of tail water,and the exploitation temperature is most affected by the amount of geothermal water.With the increase of permeability heterogeneity,the exploitation temperature of geothermal water decrease gradually,the thermal breakthrough time gradually decrease,and the maximum displacement of the thermal reservoir surface gradually change from the right side of the exploitation well to the between the exploitation well and the recharge well.(4)Based on the multi-field coupling theory of fluid,solid and heat in porous media,a multi-well model for thermal reservoir exploitation is established.The model is identified and checked by the monitoring data of geothermal water level and exploitation temperature.The evolution characteristics of flow field and temperature field of thermal reservoir under current conditions of production and irrigation are discussed and predicted.The evolution trend of thermal reservoir flow field and temperature field under different exploitation and irrigation modes are analyzed.The results show that increasing the reinjection rate of the reinjection well can reduce the rate of geothermal water level decline,but it also increase the temperature drop area.According to the reasonable well layout pattern proposed in this article,arranging new recharge wells can significantly reduce the rate of decline of geothermal water level.The research can provide theoretical and technical support for the sustainable development and utilization of porous medium reservoir,and have certain practical significance and application value.