Pollutant material flow analysis model in whole shale gas exploitation process

Abstract

The invention discloses a pollutant material flow analysis model in the whole process of shale gas exploitation, which defines and divides specific external inflow and compartment units through a material flow analysis framework, simulates the flow condition of shale gas exploitation chemical pollutants in combination with a dynamic probabilistic material flow calculation method, obtains the dynamic flow rule of the pollutants, and analyzes the pollutants in the whole process of shale gas exploitation. And determining a main period and a production link of pollutant release.

Description

Technical Field

[0001] The present invention relates to the field of site chemical pollution prevention and control, and in particular to a pollutant material flow analysis model for the entire process of shale gas extraction. Background Art

[0002] As the scale of shale gas development gradually expands, shale gas development may cause a variety of environmental problems, mainly including water resource pollution and consumption, air pollution, land pollution, etc., among which water resource pollution and consumption have attracted much attention. Under this circumstance, the research on environmental pollution related to shale gas development has gradually increased.

[0003] At present, most of the research related to shale gas development mainly discusses greenhouse gas emissions, water consumption, energy consumption, etc., as well as waste treatment technology throughout the life cycle of shale gas extraction. Among them, a study proposed a method that combines dynamic material flow analysis methods with life cycle optimization and applied it to the supply chain of the Marcellus shale gas field. The Marcellus shale gas field was evaluated for resource sustainability, but there was no systematic assessment of the environmental impact of chemical pollutants generated in each link of the shale gas extraction life cycle, and the input and flow of toxic and hazardous substances were not clarified, which failed to support the source reduction of chemical pollutants related to shale gas development.

[0004] Based on the exploration and research of predecessors, there are many material flow analysis methods, such as the open dynamic material system model (ODYM), probabilistic material flow analysis (PMFA method), dynamic probabilistic material flow analysis (DPMFA method), etc. However, China's material flow research is currently focused on metals, waste paper, building materials and certain compounds, and no one has yet been involved in the material flow analysis of chemical pollutants involved in shale gas extraction, which limits the sound management of chemicals in shale gas development.

[0005] From the above, it can be concluded that the existing technology lacks a method for logistics analysis of pollutants involved in shale gas extraction based on the shale gas extraction life cycle. It is impossible to clarify the input and flow of chemical pollutants related to shale gas extraction, and analyze their total usage, usage intensity and main production links. Summary of the invention

[0006] In view of the above problems, the present invention proposes a pollutant material flow analysis model for the whole process of shale gas extraction, which mainly solves the problems of the background technology.

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0008] A pollutant material flow analysis model for the whole process of shale gas extraction includes the following steps:

[0009] The production process of shale gas extraction is divided into several stages, and material flow analysis is performed according to the pollutants involved in each stage to build a material flow analysis framework;

[0010] Dividing the components in the material flow analysis framework into compartment units and external inflow units;

[0011] Collect empirical material flow parameters of different production links of shale gas exploitation / collect material flow in different production links, calculate material flow parameters based on transfer coefficients, and collect external inflow data for each year;

[0012] Analyzing the material flow between the external inflow unit and the compartment unit in the material flow analysis framework, thereby constructing a shale gas mining pollutant material flow analysis model;

[0013] The material flow empirical parameters and / or the material flow parameters, as well as the external inflow data are input into the shale gas production pollutant material flow analysis model, and simulation calculations are performed to obtain pollutant flow data.

[0014] In some embodiments, the stages include at least a drilling stage, a fracturing stage and a gas production stage, and the drilling stage, the fracturing stage and the gas production stage correspond to the drilling link, the fracturing and flowback link, and the gas production and water production link, respectively.

[0015] In some embodiments, each of the compartment units is divided into a flow compartment, a storage compartment, and a confluence compartment according to functional roles.

[0016] In some embodiments, the flow compartment is a compartment unit where substances temporarily stay and then are immediately released; the storage compartment is a unit compartment where substances flow in and accumulate for a period of time and are released with a delay; and the confluence compartment is a compartment where substances accumulate in the system.

[0017] In some embodiments, the method for calculating the material flow parameters includes:

[0018]

[0019] Where TC ij is the transfer coefficient, m ij is the mass of material flowing from component i to component j, ∑m i is the total mass of material flowing out of component i.

[0020] The beneficial effects of the present invention are as follows: specific external inflows and compartment units are defined and divided through a material flow analysis framework, and the flow of chemical pollutants in shale gas extraction is simulated in combination with a dynamic probabilistic material flow calculation method, the dynamic flow laws of pollutants are obtained, and the main cycles and production links of pollutant release are determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the architecture of a material flow analysis framework disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the content of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all the contents.

[0023] This embodiment proposes a pollutant material flow analysis model for the entire shale gas extraction process, including the following steps:

[0024] S1, the production process of shale gas extraction is divided into several stages, material flow analysis is carried out according to the pollutants involved in each stage, and a material flow analysis framework is constructed.

[0025] In S1, through field research, consulting professional books and related literature, combined with the shale gas extraction process, the production links mainly involving pollutants are divided into three stages: drilling stage, fracturing stage and gas production stage, which correspond to the drilling stage, fracturing and flowback stage, and gas production and produced water stage. According to the three stages and the main substances involved, a more detailed material flow analysis is carried out to obtain the following: Figure 1 The material flow analysis framework is shown.

[0026] S2, divides the components in the material flow analysis framework into compartment units and external inflow units.

[0027] In S2, both external inflow and compartment units are considered as components. Figure 1 The contents within the dotted box are considered as a system, and the contents outside the system ( Figure 1 The substances input into the system (outside the dotted box) are regarded as external inflows; in the system, according to the functions of the components ( Figure 1 Solid line box), each compartment unit is divided into flow compartment, storage compartment and confluence compartment.

[0028] The flow compartment is a compartment unit where materials temporarily stay and then are released immediately, with materials flowing in and out; the storage compartment is a unit compartment where materials flow in and accumulate for a period of time, with delayed release, with materials flowing in and out; the confluence compartment is a compartment where materials accumulate in the system, with only an inflow of materials but no outflow.

[0029] The application scenario of the technical solution of the present invention is the shale gas mining site, so the consumption and treatment of materials are regarded as the confluence compartment; the delayed release of materials involved in the gas production stage of shale gas mining is regarded as the storage compartment; the others are regarded as flow compartments. The subsequent material flow analysis model is run using the Python language, so the corresponding English symbols are compiled for each component, as shown in Table 1 below, which is a material flow model for shale gas mining pollutants.

[0030] Table 1 Division of external inflow units and compartment units

[0031] Components English symbol of component Category Total external input TotalInflow External Inflow Drilling stage Drilling Mobile compartment Fracturing gas testing stage Fracturing Mobile compartment Gas production stage Production Storage compartments Crushed rock and mineral sludge BRMS Mobile compartment Wastewater and waste liquid Wastewater Mobile compartment loss Elimination Merging compartment General solid waste treatment GST Merging compartment Hazardous waste treatment HST Merging compartment Recycling Recycling Merging compartment Shale gas wastewater treatment plant STP Merging compartment

[0032] S3, collect empirical material flow parameters of different production links of shale gas exploitation / collect material flow rates of different production links, calculate material flow parameters based on transfer coefficients, and collect external inflow data of each year.

[0033] Step S3 aims to obtain material flow data of different production links of shale gas exploitation. The material flow analysis model parameters established in this method are mainly empirical parameters or transfer coefficients TC ij For different pollutants, the parameters will be different. Before sorting out the parameters, it is necessary to widely collect empirical parameters of different links in shale gas extraction; or collect material flow in different links and calculate the parameters according to the transfer coefficient formula. Empirical parameters are generally data provided by experts or literature, which can be used in the model after sorting.

[0034] Among them, the transfer coefficient TC ij is the ratio of the mass of material flowing from component i to component j to the total mass of material flowing out of component i. Therefore, the calculation method of the material flow parameter described in S3 includes:

[0035]

[0036] Where TC ij is the transfer coefficient, m ij is the mass of material flowing from component i to component j, ∑m i is the total mass of material flowing out of component i.

[0037] In addition, it is also necessary to collect external inflow data for each year. External inflow data mainly refers to the sum of the content of a specific pollutant in the materials input and involved in the drilling stage, fracturing stage, and gas production stage.

[0038] S4, analyzing the material flow between the external inflow unit and the compartment unit in the material flow analysis framework, thereby constructing a shale gas extraction pollutant material flow analysis model.

[0039] In S4, the basic idea of ​​analyzing material flow is to use the law of conservation of mass, assuming that the total mass of the material (especially the pollutants) in the system is constant. Specifically, a material analysis simulator can be used. The material analysis simulator can simulate the physical, chemical and mechanical properties of the material, as well as its behavior under different conditions, thereby providing a scientific basis and technical support for the research and development, production and application of the material. In this embodiment, the simulation function is used to simulate the actual application environment and working conditions of the material and predict the flow direction of the material.

[0040] In one example, the material analysis simulator may use the dpmfa package, which is a simulator for dynamic probabilistic material flow analysis (Dynamic Probabilistic Material Flow Analysis). It is developed based on the Python language and is mainly used to simulate and analyze dynamic probabilistic changes in the material flow process.

[0041] The shale gas extraction pollutant material flow analysis model established by S4 can clarify the input and flow of chemical pollutants, analyze their total usage and intensity; simulate the flow of shale gas extraction pollutants and their occurrence in different media, and quantify the material quantity relationship of pollutants in different media; it can quantitatively analyze the release characteristics and release amounts of pollutants from construction to gas production, and determine the main cycles and production links of pollutant release.

[0042] S5, inputting material flow empirical parameters and / or material flow parameters, as well as external inflow data into a shale gas extraction pollutant material flow analysis model, and performing simulation calculations to obtain pollutant flow data.

[0043] In one example, the model uses years as the time unit, and one year is a cycle. The external inflow data uses the function ExternalListInflow in the dpmfa package to define and call data values; the flow of each cycle is expressed by the functions FixedValueInflows, StochasticInflow, and RandomChoiceInflow. FixedValueInflows is a constant function, that is, the data is a constant value; the other two are probability distribution functions. The flow compartment uses StochasticTransfer or ConstTransfer to represent the parameters; StochasticTransfer uses probability distribution functions and parameter lists for parameterization. According to actual conditions, the selected probability distribution function is triangular; ConstTransfer uses deterministic data for parameterization. The confluence compartment uses ListRelease or FunctionRelease to represent the release rate. ListRelease uses a list to represent the release rate of each future cycle, and FunctionRelease uses a mathematical formula to represent the future release rate. The parameter uncertainty of the flow correlation between the system interval and the absolute annual inflow is represented by the Bayesian probability distribution; the propagation of parameter uncertainty through the model during the entire simulation time is achieved by the Monte Carlo method.

[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A pollutant material flow analysis model for the whole process of shale gas extraction, characterized in that: The following steps are involved: The production process of shale gas extraction is divided into several stages, and material flow analysis is performed according to the pollutants involved in each stage to build a material flow analysis framework; Dividing the components in the material flow analysis framework into compartment units and external inflow units; Collect empirical material flow parameters of different production links of shale gas exploitation / collect material flow in different production links, calculate material flow parameters based on transfer coefficients, and collect external inflow data for each year; Analyzing the material flow between the external inflow unit and the compartment unit in the material flow analysis framework, thereby constructing a shale gas mining pollutant material flow analysis model; The material flow empirical parameters and / or the material flow parameters, as well as the external inflow data are input into the shale gas production pollutant material flow analysis model, and simulation calculations are performed to obtain pollutant flow data.

2. The pollutant material flow analysis model for the whole process of shale gas extraction according to claim 1 is characterized in that: The stages include at least a drilling stage, a fracturing stage and a gas production stage, wherein the drilling stage, the fracturing stage and the gas production stage correspond to the drilling link, the fracturing and flowback link, and the gas production and produced water link respectively.

3. The pollutant material flow analysis model for the whole process of shale gas extraction according to claim 1 is characterized in that: The compartment units are divided into flow compartments, storage compartments and confluence compartments according to their functional roles.

4. The pollutant material flow analysis model for the whole process of shale gas extraction according to claim 3 is characterized in that: The flow compartment is a compartment unit where materials temporarily stay and then are released immediately; the storage compartment is a unit compartment where materials flow in and accumulate for a period of time and are released with a delay; the confluence compartment is a compartment where materials accumulate in the system.

5. The pollutant material flow analysis model for the whole process of shale gas extraction according to claim 1, characterized in that: The calculation method of the material flow parameters includes: Where TC ij is the transfer coefficient, m ij is the mass of material flowing from component i to component j, ∑m i is the total mass of material flowing out of component i.

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