| At present,the primary problems of sustainable development of human beings in society are energy and environmental problems.Due to its wide distribution,sustainable development and stable operation,geothermal energy have been focused on research and development by countries around the world.Petrothermal resources are geothermal resources that are endowed with solid rocks.Enhanced geothermal systems(EGS)are an effective way to develop petrothermal resources.During EGS development,the heat-lifting fluid enters the thermal reservoir through the injection well and moves along the fracture.And heat-lifting fluid exchanges heat with the rock in the reservoir fracture network and extracts the high-temperature fluid from the production well for power generation and comprehensive utilization.After the injection of the water injection and the high-temperature thermal storage rock mass,the water-rock interaction occurs,causing mineral dissolution or precipitation,which causes changes in the porosity and permeability of the reservoir,changing the production capacity of the system and affecting the development of geothermal energy.Based on the above problems,this paper takes the high-temperature thermal storage in the Raised Area of Matouying,Hebei Province as the research object,collects groundwater and seawater of the local Guantao Formation formation as the water injection body.This paper conducts indoor static water-rock interaction experiments to qualitatively determine the dissolution and sedimentation trend of minerals.Based on the static water-rock experiment,PHREEQC is used for reverse simulation to quantitatively determine the reaction amount of mineral dissolution and precipitation.Taking formation water as injection and production water,the indoor core flowing experiment is carried out to obtain the changing trend of rock column permeability and hydrochemical composition of formation water after the reaction.The reactive solute transport model is established by TOUGHREACT,the water-rock interaction core flow experiment is simulated,and the parameter conditions in the conceptual model of the water-rock interaction core flow experiment are corrected.Taking the high-temperature geothermal reservoir in matouying uplift of Hebei Province as the research object,the one-dimensional site flow model of water-rock interaction is established based on the high-temperature geothermal reservoir in the Matouying raised area of Hebei Province.The three types of water injection and recovery water body schemes of formation water,seawater,and treated seawater are designed.Experiments are carried out at different time scales and under different injection water body conditions.The forward numerical simulation of rock interaction studies the changing trend,porosity,and permeability of reservoir minerals,and proposes a water injection and recovery scheme suitable for enhanced geothermal systems in this region.The main insights from this study are as follows:(1)The results of indoor static experiments on water-rock interaction show that after the interaction between the formation water and the reservoir rock sample in Matouying District,the feldspar first dissolves and then precipitates,the dolomite dissolves,and the chlorite and calcite precipitate occurs.After the water-rock interaction between the Bohai Seawater and the reservoir rock sample,the feldspar first dissolves and then precipitates,and the calcite precipitates and a large number of zeolite precipitates.The reverse simulation results of the static experiment in the rock interaction room showed that after the water-rock interaction between the formation water and the high-temperature thermal storage rock in the Matouying raised area,the dissolution of quartz,potassium feldspar,dolomite,and calcium feldspar occurred and the precipitation of chlorite,kaolinite,and calcite occurred.After the reaction between seawater and the high-temperature thermal storage rock in the Matouying raised area of Hebei Province,albite occurred.Calcium feldspar dissolves and forms kaolinite and zeolite precipitates.(2)The experimental results of the core flow of water-rock interaction show that the permeability of the rock column shows an increasing trend.Through the analysis of the water chemical components,it is obtained that potassium feldspar is always in a weak precipitation state,the sodium feldspar part of the oblique feldspar is always in a dissolved state,and the chlorite or dolomite is in a large dissolved state during the experiment.Ca2+dissolved and released into the solution by the dissolution of the sky dolomite participated in the precipitation of calcite from 0 to 35 days,and after 35 days,Ca2+in the reactive water sample began to participate in the precipitation of calcite.The Si O2 released after the dissolution of each silicate rock mineral in the rock sample takes away only a small part in the reaction solution,and most of it exists in the form of quartz or other silicate minerals.(3)The one-dimensional site flow model of water-rock interaction shows that the seawater reacts for 10 years,the local porosity is reduced from 0.1 to 0.03989,and the permeability is from 1×10-13m~2 to 0.678×10-13m~2,and a large number of zeolite minerals precipitated.The local minimum porosity of the treated seawater after 10 years is 0.06207,and the permeability is reduced to 0.797×10-13m~2,the main precipitated mineral is zeolite,and the precipitated mineral species is single and appears in the injection wellhead.The local minimum porosity is 0.07168 after 10 years of formation water reaction,and the permeability is reduced to 0 0.849×10-13m~2,the precipitated minerals are calcite and quartz,calcite mainly appears near the injection well,and quartz mainly appears away from the injection well.(4)Analysis of the scheme of water injection and recovery body:seawater is not suitable as an injection water body,and after treatment,seawater(seawater removal Na+and Cl-600mmol/L each)is convenient for subsequent deblocking work as water injection and production body.Formation water as water injection and production body have the weakest porosity reduction,and the system production capacity and heat efficiency are the highest. |
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