Search

CN-122021407-A - High-salt mine water deep stratum reinjection chemical blockage prediction simulation method

CN122021407ACN 122021407 ACN122021407 ACN 122021407ACN-122021407-A

Abstract

The invention provides a method for predicting and simulating reinjection chemical blockage of deep stratum of high-salt mine water, which comprises the steps of analyzing the water chemical characteristics of reinjection water and deep reinjection layer groundwater and the content of mineral components of the reinjection layer, and (3) establishing a water rock reaction mineral list, combining the nonlinear influence of mineral reaction kinetics and high TDS (total dissolved solids) on the reaction rate, constructing a groundwater flow-chemical reaction coupling model, and simulating the mineral precipitation process and the influence of the mineral precipitation process on the porosity. And finally, a risk index (CRI) early warning model based on porosity change rate is established, quantitative evaluation and grading early warning of the blockage risk of the reinjection well are realized, and scientific basis is provided for guiding blockage dredging measures and prolonging the service life of the well hole.

Inventors

  • WANG ZHIBO
  • WANG TIANTIAN
  • XUE JIANKUN
  • ZHOU ZHENFANG
  • HAN LE
  • WANG YUTONG

Assignees

  • 中煤科工西安研究院(集团)有限公司

Dates

Publication Date
20260512
Application Date
20260106

Claims (10)

  1. 1. A high-salt mine water deep stratum reinjection chemical blockage prediction simulation method comprises the following steps: s1, determining water quality and reinjection layer parameters; s2, establishing a reaction mineral list, and calculating a kinetic rate constant; s3, calibrating a nonlinear influence coefficient of high TDS on the reaction rate through an experiment; S4, constructing a mine water reinjection numerical model by utilizing the parameters determined in the S1, and simulating a reinjection process; s5, based on the mineral list and the reaction parameters obtained by S2 and S3, coupling chemical reaction in a model, and identifying main blocked minerals S6, calculating porosity change rate caused by mineral precipitation; s7, establishing a CRI risk early warning model based on the porosity change rate, and outputting a risk grade.
  2. 2. The method for predicting the chemical blockage of the reinjection of the deep stratum of the high-salinity mine water according to claim 1, wherein the step S1 specifically comprises the steps of obtaining reinjection water quality parameters, injection parameters, reinjection layer hydrogeological parameters, physicochemical properties and groundwater quality parameters: s101, performing well-feeding construction and data acquisition work of a DTS optical fiber, analyzing a water injection section, identifying a water absorption layer section and determining a reinjection target layer; s102, collecting mine water and reinjection layer underground water, and performing water quality simple analysis to analyze reinjection water, in-situ water characteristic ions, water chemical types and deep stratum acid-base environment; S103, calculating the temperature and pressure of the reinjection target layer, and determining the layer position thickness, reinjection flow and water temperature of the reinjection target layer; and S104, digital core analysis, namely carrying out porosity extraction analysis, seepage simulation analysis and component analysis on the core of the reinjection target layer, and determining the lithology, mineral component content and density, porosity and permeability parameters of the reinjection layer.
  3. 3. The method for predicting chemical blockage by reinjection into the deep stratum of the high-salinity mine water according to claim 1 or 2, wherein the step S2 specifically comprises the steps of establishing a mineral list, calculating a kinetic rate constant, namely establishing a mineral list participating in reaction according to the analysis result of water quality and core components, calculating a kinetic rate constant k of minerals under the high-temperature and high-pressure environment of the deep stratum and under neutral, acidic and alkaline 3 mechanisms, wherein the calculation formula is as follows: ; Wherein, the upper and lower labels nu, H and OH respectively represent a neutral mechanism, an acidic mechanism and an alkaline mechanism; 、 ; respectively represent kinetic rate constants at 25 ℃ in neutral, acidic and basic mechanisms; 、 、 R is a gas constant, 8.314J/(mol.K), T is the absolute temperature of the deep stratum environment, K; 、 respectively, the activity of related ions in an acidic mechanism and an alkaline mechanism, and m is an index term related to specific reactions.
  4. 4. The method for predicting chemical plugging by reinjection into deep stratum of high-salinity mining water according to claim 1, wherein S3 comprises the specific steps of experimentally calibrating a nonlinear influence coefficient of high TDS introduced to reaction rate of insoluble minerals Preparing gradient TDS solution with concentration of 10000-80000 mg/L, performing mineral precipitation experiment in a high-pressure reaction kettle, on-line monitoring concentration attenuation of corresponding ions by ICP-OES, calculating actual measurement value of reaction rate r, and fitting The ion intensity decay coefficient alpha is obtained, ; Calculated by the following formula: ; In the formula, The method is characterized in that the method is an ideal mineral reaction rate, mol/s, k is a kinetic rate constant, mol/(m 2 & s), A is the surface area of a reaction mineral, m 2 , omega is a mineral saturation index, theta and eta are empirical constants, and I is the ionic strength.
  5. 5. The method for predicting and simulating the chemical blockage of the reinjection of the deep stratum of the high-salinity mine water according to claim 1 or 2 is characterized in that the S4 specifically comprises the steps of constructing a mine water reinjection numerical model: s401, carrying out regional hydrogeological investigation to find out the distribution, structural development conditions and boundary conditions of the upper and lower aquifers and the water-resisting layer of the reinjection layer; s402, a conceptual model is established, the depth range and the horizontal range of the reinjection layer are determined, and mesh division is carried out on the reinjection layer in the vertical direction and the horizontal direction; s403, setting reinjection position, injection flow, injection water temperature, formation temperature and pressure, porosity and other parameter conditions by giving boundary conditions and initial conditions; S404, simulating the flowing direction of groundwater in the reinjection process, the temperature and pressure changes of different positions of the stratum and the mixing ratio of the two types of water by adopting a finite volume or finite integral difference numerical method.
  6. 6. The method for predicting chemical plugging of deep water stratum in high salt mine according to claim 1 or 2, wherein the step S5 comprises determining main plugging mineral components and occurrence positions, namely using calculated mineral reaction rate constant and nonlinear influence coefficient lambda (I) of high TDS on insoluble mineral reaction rate, based on mine water reinjection numerical model, entering a simulation program to open a chemical reaction switch to couple water chemical reaction, and determining main plugging mineral components and occurrence positions, wherein the method comprises the following steps: S501, setting water chemistry environment parameters including main ion components, secondary complexes, mineral components and dynamic parameters thereof, gas components, adsorption and decay effects and cation exchange effects of reinjection water and deep groundwater, wherein the dynamic parameters and nonlinear influence coefficients in deep stratum and high-salt environment are obtained by the steps S2 and S3; s502, setting water chemistry calculation and output control, including simulation time, solving and convergence conditions, input and output files, output control and parameter partition, arranging monitoring points in a blocking area, and simulating water quality change and ion concentration of the monitoring points; S503, calculating the ion activity product IAP of the related indissolvable minerals according to the ion concentrations of the monitoring points, comparing with the solubility product constant K sp to determine the main precipitated minerals causing the blockage, if IAP < K sp , the main precipitated minerals are in an unsaturated state and are not precipitated, if IAP > K sp , the main precipitated minerals are in a supersaturated state, the main precipitated minerals are judged to be the main precipitated minerals.
  7. 7. The method for predicting chemical plugging in a deep water formation in a high salt mine of claim 6, wherein the IAP is calculated by the following formula: ; ; ; ; In the formula, Representing the activity of ions; Is a cation Activity of (2); Is an anion E is the cation metering coefficient in the chemical formula, f is the anion metering coefficient in the chemical formula; Representing the activity coefficient; the concentration of ions is indicated as being, The concentration of the ion i is mg/L, which is obtained by simulation, A is Debye-Houk's constant, and the value is 0.51; The number of charges representing the ions is represented, Is the charge number of the ion I, and I represents the ionic strength and mol/L of the solution.
  8. 8. The method for predicting chemical plugging by reinjection into a deep formation in a high salt mine water according to claim 6, wherein the method comprises the steps of The calculation of (1) comprises: Calculating solubility product constant of minerals in deep formation environment using van-terjov equation The calculation formula is as follows: ; In the formula, Is the absolute temperature, K, of the deep formation environment; Is a standard solubility product constant at 25 ℃, and can be obtained by looking up a table; The standard reaction enthalpy change at 25 ℃ is J/mol, and can be obtained through table lookup calculation; Is a gas constant, 8.314J/(mol.K).
  9. 9. The method for predicting chemical blockage of deep stratum reinjection of high-salinity mine water according to claim 1 or 2, wherein the step S6 comprises the steps of simulating and calculating porosity change rate, namely simulating volume fraction change of main precipitated minerals and expansion of a precipitation change area on the basis of determining the type of the blocked secondary minerals, extracting volume fraction data of the mineral precipitation in different monitoring areas to obtain the distribution of porosity of the reinjection layer along with time, and calculating the porosity change rate gamma i caused by each mineral precipitation according to the operation age and the porosity change size of the system; ; Wherein i is the ith precipitated mineral, delta phi i is the porosity change caused by the ith precipitated mineral, and delta t is the running simulation time a.
  10. 10. The method for predicting chemical blockage of deep stratum reinjection of high-salinity mine water according to claim 1 or 2, wherein the step S7 specifically comprises the steps of establishing a risk early warning model, determining the specified service life of the reinjection well, and providing an early warning model based on a risk index CRI according to the porosity change rate calculated by simulation: ; In the formula, The sum of the change of the porosity caused by each precipitated mineral in the operation time is given, n is the average effective porosity of the reinjection layer, x is the service life a of the specified reinjection well; When CRI <1, the porosity reduction rate caused by chemical precipitation is considered to be within the normal variation range of the specified service life, the risk is judged to be low, when CRI <1.5 is not more than 1, the later period of reinjection is easy to block, certain blocking-free measures are needed, when CRI <1.5 is not less than 1, the porosity variation rate is high, the blocking risk is high, and a full period back commentary and subcommentary blocking scheme is needed to be formulated and implemented.

Description

High-salt mine water deep stratum reinjection chemical blockage prediction simulation method Technical Field The invention belongs to the field of mine water protection of coal mines, and relates to a chemical blockage prediction simulation method for deep stratum reinjection of high-salt mine water. Background The deep well reinjection technology is widely applied as a means with wide applicability, safety, economy and high efficiency, and correspondingly, the high-salt mine water is injected into a stratum which is special in the deep part of the underground, isolated from a shallow water-bearing layer and surface water and has enough water storage space, so that the purposes of safe disposal, environmental pollution avoidance and shallow water resource protection are achieved. It is noted that unlike shallow formation reinjection, deep formation high temperature, high pressure formation environment and high salt acid groundwater environment, water-water reaction and water-rock reaction occur during reinjection to cause complex chemical blocking problem. The chemical phase and the concentration difference of soluble salts exist between the reinjection water and the original groundwater, the migration and transformation of ionic components in the reinjection process can change the groundwater environment of the deep stratum, the temperature and pressure change and the accumulation of characteristic ions such as SO 42- and the like, and the components such as calcium, magnesium and the like in the water form mineral precipitation due to supersaturation, SO that the permeability of the aqueous medium is changed, and the pore blockage is caused to influence the reinjection efficiency. The traditional reinjection chemical blocking prediction method is mainly applied to the fields of underground water super-recovery reinjection, geothermal tail water reinjection and the like, and is not proposed aiming at the problems that the deep stratum reinjection of high-salt mine water is difficult to sample and monitor and the pre-warning model is not proposed yet, so that the chemical blocking prediction simulation method and the risk pre-warning model in the reinjection process of the deep stratum of the high-salt mine water are urgently needed to be established. Disclosure of Invention The invention aims to provide a chemical blockage prediction simulation method and a risk early warning model for reinjection of a deep stratum of high-salt mine water, by the method, the evolution of the chemical environment of the deep stratum water under the influence of reinjection can be identified, the main control components and the space-time positions of the chemical blockage are predicted, the risk early warning model is established, and the dredging scheme is guided to be implemented, so that the service life of a well hole is prolonged. In order to achieve the above purpose, the invention adopts the following technical scheme: A high-salt mine water deep stratum reinjection chemical blockage prediction simulation method comprises the following steps: s1, determining water quality and reinjection layer parameters; s2, establishing a reaction mineral list, and calculating a kinetic rate constant; s3, calibrating a nonlinear influence coefficient of high TDS on the reaction rate through an experiment; S4, constructing a mine water reinjection numerical model by utilizing the parameters determined in the S1, and simulating a reinjection process; s5, based on the mineral list and the reaction parameters obtained by S2 and S3, coupling chemical reaction in a model, and identifying main blocked minerals S6, calculating porosity change rate caused by mineral precipitation; s7, establishing a CRI risk early warning model based on the porosity change rate, and outputting a risk grade. Optionally, the step S1 specifically comprises the steps of obtaining reinjection water quality parameters, injection parameters, reinjection layer hydrogeological parameters, physical and chemical properties and groundwater quality parameters: s101, performing well-feeding construction and data acquisition work of a DTS optical fiber, analyzing a water injection section, identifying a water absorption layer section and determining a reinjection target layer; s102, collecting mine water and reinjection layer underground water, and performing water quality simple analysis to analyze reinjection water, in-situ water characteristic ions, water chemical types and deep stratum acid-base environment; S103, calculating the temperature and pressure of the reinjection target layer, and determining the layer position thickness, reinjection flow and water temperature of the reinjection target layer; and S104, digital core analysis, namely carrying out porosity extraction analysis, seepage simulation analysis and component analysis on the core of the reinjection target layer, and determining the lithology, mineral component content and density, porosity and permeabi