A Study On Parameter Identification And Energy Extraction Optimization Of Medium-low Temperature Sandstone Geothermal Reservoir In Minghua Formation Of Renxian

With the rapid development of economy and industrialization,China's demand for energy is increasing year by year,but China's energy structure is still dominated by coal.This energy structure not only severely pollutes the environment,but also increases CO₂ emissions and exacerbates the global greenhouse effect.In this context,China has proposed the strategy of "carbon neutrality".In order to achieve the dual carbon goal,China needs to accelerate the adjustment of its energy mix and give better play to the role of renewable energy while ensuring sustainable economic development.As a kind of clean,stable and renewable energy with wide distribution,huge reserves,geothermal energy has been widely promoted and used.Geothermal energy resources in China are extremely abundant,but the exploration rate and utilization rate of geothermal energy resources are not high,and the distribution is not uniform under the influence of magmatic activities and hydrogeological conditions.At present,low temperature geothermal resources are mainly exploited in China,among which hydrothermal geothermal resources are the main geothermal resources,and their distribution has certain regularity.The geothermal resources in Renxian,Xingtai City,Hebei Province are abundant,with suitable burial depth and great development potential.At the same time,Hebei government issued the geothermal development policy of "taking heat but not water",which put forward higher requirements for the development and utilization of geothermal engineering.Drilling cost accounts for a large proportion in geothermal development projects.How to design reasonable engineering parameters and exploitation mode to ensure sustainable development and utilization of geothermal resources and meet the requirements of "taking heat but not water" has become the key to geothermal development projects.In conclusion,based on the low temperature heat reservoir sandstone in geothermal exploitation of containing water thermal transport problems and wellbore reservoir coupling problem,adopt "collect data,theory analysis,numerical simulation research" the way of combining sandstone thermal storage at low temperature geothermal exploitation system in the establishment of wellbore reservoir coupling model,the identification and correction of sandstone reservoir water hot parameters,The analysis of water-heat output and temperature-pressure field variation of sandstone thermal reservoir geothermal exploitation provides an effective method for parameter identification and productivity optimization of middle-low warm water thermal geothermal system in China.Base on sandstone geothermal reservoir of Renxian,Ming group,geological situation,formation conditions and geothermal geological conditions and well logging data of the Renxian regional were collected and organized.The structural characteristics of middle and low temperature geothermal reservoirs in Renxian are comprehensively analyzed,which provides a basis for establishing numerical model of sandstone thermal reservoir geothermal system for parameter identification and productivity optimization.A one-dimensional natural steady-state heat transfer model was established.The reservoir layers were stratified based on the temperature distribution law of conduction thermal reservoir,and the steady-state log temperature measurement curve of CNOOCRX-1 well was fitted to obtain the thermal conductivity of each stratified formation.Based on the steady-flow pumping test of CNOOCRX-1 well,a boreholereservoir coupling numerical model was established.On the basis of identifying the distribution of thermal conductivity,the variation process of measured data under different drawdown was fitted to obtain the permeability parameters at different depths in the perforation section.In order to verify the accuracy of the reservoir hydrothermal parameters,a three-dimensional well-reservoir coupling numerical model of the geothermal system was established,the flow rate and dynamic water level data were the same as the historical heating data of CNOOCRX-1 and CNOOCRX-2 Wells,calculation of numerical model of flow temperature and injection pressure and the error of the measured values,The accuracy of the numerical model to identify hydrothermal parameters is verified.The distribution of thermal conductivity and permeability after identification and correction increases the data basis for long-term performance prediction and productivity optimization of geothermal doublet system.At present,the development and utilization mode of medium-low temperature sandstone heat reservoir in Minghua Town Formation of Renxian is doublet mode.Based on the data obtained from the identification of hydrothermal parameters,a borehole-reservoir coupling numerical model is established.Taking CNOOCRX-1 and CNOOCRX-2 geothermal systems as an example,the dynamic heat recovery characteristics of the system under long-term operation(50 years)are analyzed,and the key engineering parameters of the geothermal system are optimized.The simulation results show that increasing the production and irrigation flow rate,decreasing the injection temperature and decreasing the perforation section length will lead to a significant increase in the pressure of the injection well.Considering the heat recovery capacity and operation cost of the system,the flow rate of 80 m~3/h,the recharge temperature of 10 ?,the spacing between the Wells of 300 m and the length of perforation section of 300 m were selected.