Prediction Method and System for Gas-Water Ratio Parameter of Tight Gas Reservoir Based on Chloride Ion Concentration

Abstract

The present application discloses a method and system for predicting the gas-water ratio parameter of a tight gas reservoir based on the chloride ion concentration. The method includes: obtaining a test water production sample of the tight gas reservoir and collecting data on the chloride ion concentration of the water sample to obtain the chloride ion concentration parameter of the formation water sample; selecting the coefficients of the regional gas-water ratio calculation model to construct a gas-water ratio parameter prediction model; performing gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir. The embodiments of the present application can construct a gas-water ratio parameter calculation model by combining the chloride ion concentration parameter of the formation water, improving the prediction accuracy of the gas-water ratio parameter in the tight gas production process. The present application can be widely applied to the technical field of gas-water ratio prediction for tight gas reservoirs.

Description

Technical Field

[0001] This application relates to the technical field of predicting gas-water ratio in tight gas reservoirs, and particularly to a method and system for predicting gas-water ratio parameters in tight gas reservoirs based on chloride ion concentration. Background Art

[0002] The gas-water relationship in tight gas reservoirs is complex. The reservoirs have well-developed micro-pores, high irreducible water saturation, and small differences and low contrasts in the logging response characteristics between oil and gas layers and water layers, as well as between industrial production layers and low-production layers, making it difficult to identify by logging. To increase the gas production of tight gas, fracturing is currently often used to transform tight gas reservoirs to generate more micro-fractures to connect the gas production channels between the reservoirs and the wellbores. However, the fracturing process often easily converts the bound water in tight gas reservoirs into mobile water. Therefore, gas and water are often produced simultaneously during the exploitation of tight gas. For this reason, oilfield technicians need to accurately evaluate the gas-water ratio parameters during the exploitation of tight gas through various geological data to formulate the optimal development implementation plan and production allocation plan for tight gas reservoirs. The existing methods include the trial production method and the logging prediction method. Among them, the logging prediction method has high timeliness, but it depends on rich logging data and core laboratory analysis results, and the process of determining the prediction model parameters has a long cycle, resulting in poor accuracy of the prediction model. The trial production method is expensive and has a long operation cycle, and cannot meet the evaluation requirements of tight gas reservoirs.

[0003] In summary, the technical problems existing in the related art need to be improved. Summary of the Invention

[0004] The main purpose of the embodiments of this application is to propose a method and system for predicting gas-water ratio parameters in tight gas reservoirs based on chloride ion concentration, which can construct a gas-water ratio parameter calculation model by combining the chloride ion concentration parameters of formation water and improve the prediction accuracy of gas-water ratio parameters during the production of tight gas.

[0005] To achieve the above purpose, on the one hand, an embodiment of this application proposes a method for predicting gas-water ratio parameters in tight gas reservoirs based on chloride ion concentration, and the method includes:

[0006] Obtain a test water production sample from a tight gas reservoir and collect water sample chloride ion concentration data to obtain the chloride ion concentration parameter of the formation water sample;

[0007] Select the coefficients of the regional gas-water ratio calculation model and construct a gas-water ratio parameter prediction model;

[0008] Perform gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir.

[0009] In some embodiments, the obtaining a test water production sample from a tight gas reservoir and collecting water sample chloride ion concentration data to obtain the chloride ion concentration parameter of the formation water sample includes:

[0010] Obtain the produced water sample of the tight gas reservoir test through an in-situ downhole formation water sampler;

[0011] Collect data on the chloride ion concentration of the produced water sample of the tight gas reservoir test to obtain the chloride ion concentration parameter of the formation water sample.

[0012] In some embodiments, obtaining the produced water sample of the tight gas reservoir test through the in-situ downhole formation water sampler includes:

[0013] Determine the area to be studied;

[0014] Lower the in-situ downhole formation water sampler to the depth of the production interval in the area to be studied for extraction to obtain a preliminary produced water sample of the tight gas reservoir test;

[0015] Transport and package the preliminary produced water sample of the tight gas reservoir test through a heat-insulating and pressure-holding sample cylinder to obtain the produced water sample of the tight gas reservoir test.

[0016] In some embodiments, collecting data on the chloride ion concentration of the produced water sample of the tight gas reservoir test to obtain the chloride ion concentration parameter of the formation water sample includes:

[0017] Perform precipitation and filtration on the produced water sample of the tight gas reservoir test to obtain a filtered produced water sample of the tight gas reservoir test;

[0018] Based on a preset ambient temperature, collect data on the filtered produced water sample of the tight gas reservoir test through a chloride ion sensor to obtain a preliminary chloride ion concentration parameter;

[0019] Based on a preset ambient temperature, collect data on the filtered produced water sample of the tight gas reservoir test through a conductivity sensor to obtain a conductivity parameter;

[0020] Integrate the preliminary chloride ion concentration parameter and the conductivity parameter to determine the chloride ion concentration parameter of the formation water sample.

[0021] In some embodiments, selecting the coefficient of the regional gas-water ratio calculation model to construct a gas-water ratio parameter prediction model includes:

[0022] Select the coefficient of the regional gas-water ratio calculation model;

[0023] Obtain the tight gas production data of several horizons in the tight gas reservoir to determine the gas-water ratio parameters of the horizons;

[0024] Obtain the tight gas formation water samples of several horizons in the tight gas reservoir to determine the chloride ion concentration data of the formation water of the horizons;

[0025] Taking the gas-water ratio parameter of the horizon as the abscissa and the chloride ion concentration data of the formation water in the horizon as the ordinate, construct a relationship diagram between the gas-water ratio and the measured chloride ion concentration value of the produced water;

[0026] Based on the relationship diagram between the gas-water ratio and the measured chloride ion concentration value of the produced water, introduce the coefficient of the regional gas-water ratio calculation model to construct the gas-water ratio parameter prediction model.

[0027] In some embodiments, the coefficient of the regional gas-water ratio calculation model includes a first control index parameter and a second control index parameter, and the coefficient of the regional gas-water ratio calculation model is determined by regional tight gas testing.

[0028] In some embodiments, the expression of the gas-water ratio parameter prediction model is specifically as follows:

[0029] GW = a×e (b×CL)

[0030] In the above formula, GW represents the gas-water ratio parameter, a and b represent the coefficients of the regional gas-water ratio calculation model, e represents the natural logarithm base, and CL represents the chloride ion concentration parameter of the formation water sample.

[0031] In some embodiments, the gas-water ratio prediction process for the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir includes:

[0032] Input the chloride ion concentration parameter of the formation water sample into the gas-water ratio parameter prediction model;

[0033] Perform exponential calculation prediction processing on the chloride ion concentration parameter of the formation water sample to obtain the gas-water ratio parameter of the tight gas reservoir.

[0034] In some embodiments, it further includes storing the gas-water ratio parameter of the tight gas reservoir for tight gas reservoir reserve evaluation and preparing the development implementation plan for the tight gas reservoir well.

[0035] To achieve the above object, on the other hand, an embodiment of the present application proposes a tight gas reservoir gas-water ratio parameter prediction system based on chloride ion concentration, and the system includes:

[0036] The first module is used to obtain the tight gas reservoir test produced water sample and collect the chloride ion concentration data of the water sample to obtain the chloride ion concentration parameter of the formation water sample;

[0037] The second module is used to select the coefficient of the regional gas-water ratio calculation model and construct the gas-water ratio parameter prediction model;

[0038] The third module is used to perform gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir.

[0039] The embodiments of the present application at least include the following beneficial effects: The present application provides a method and system for predicting the gas-water ratio parameter of a tight gas reservoir based on chloride ion concentration. This solution obtains the produced water samples of the tight gas reservoir and collects the chloride ion concentration data of the water samples to obtain the chloride ion concentration parameters of the formation water samples. Then, it selects the calculation model coefficients of the regional gas-water ratio, constructs a gas-water ratio parameter prediction model, and finally performs gas-water ratio prediction processing on the chloride ion concentration parameters of the formation water samples based on the gas-water ratio parameter prediction model. It is not necessary to collect additional geological basic data, and there is no data collection operation cost. Only by processing and mining the existing geological data can the calculation of the gas-water ratio parameter be realized. It can construct a gas-water ratio parameter calculation model by combining the chloride ion concentration parameters of the formation water, and improve the prediction accuracy of the gas-water ratio parameter in the tight gas production process. Description of the Drawings

[0040] Figure 1 is a flowchart of the method for predicting the gas-water ratio parameter of a tight gas reservoir based on chloride ion concentration provided by the embodiments of the present application;

[0041] Figure 2 is a schematic structural diagram of the system for predicting the gas-water ratio parameter of a tight gas reservoir based on chloride ion concentration provided by the embodiments of the present application;

[0042] Figure 3 is a schematic diagram of the relationship between the gas-water ratio and the chloride ion concentration value of the produced water for testing provided by the embodiments of the present application;

[0043] Figure 4 is a schematic diagram of a tight gas reservoir well provided by the embodiments of the present application. Detailed Embodiments

[0044] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of systems and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0045] It will be understood that the terms "first", "second", etc. used in this application may be used herein to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if", "when" as used herein may be interpreted as "when...", "while...", or "in response to determining".

[0046] The terms "at least one", "a plurality", "each", "any one", etc. used in this application, where at least one includes one, two, or more than two, a plurality includes two or more than two, each refers to each of the corresponding plurality, and any one refers to any one of the plurality.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0048] Refer to Figure 1 , Figure 1 is a flowchart of a method for predicting the gas-water ratio parameter of a tight gas reservoir based on the chloride ion concentration provided by an embodiment of the present invention. Refer to Figure 1 , the method includes the following steps:

[0049] S100. Obtain a test produced water sample from the tight gas reservoir and collect data on the chloride ion concentration of the water sample to obtain the chloride ion concentration parameter of the formation water sample;

[0050] It should be noted that in some embodiments, step S100 may include: S110. Obtain a test produced water sample from the tight gas reservoir through an in-situ sampling instrument for formation water downhole; S120. Collect data on the chloride ion concentration of the test produced water sample from the tight gas reservoir to obtain the chloride ion concentration parameter of the formation water sample.

[0051] Furthermore, it should be noted that in some embodiments, step S110 may include: S111. Determine the area to be studied; S112. Lower the in-situ sampling instrument for formation water downhole to the depth of the production interval of the area to be studied for extraction to obtain a preliminary test produced water sample from the tight gas reservoir; S113. Transport and package the preliminary test produced water sample from the tight gas reservoir through a heat-insulating and pressure-holding sample cylinder to obtain the test produced water sample from the tight gas reservoir.

[0052] In this embodiment, the downhole formation water in-situ sampling instrument is lowered to the depth of the production interval to sample the water produced from the test production section of the tight gas reservoir. The downhole sampled samples are loaded into a heat-insulated and pressure-maintained sample cylinder to avoid contamination of the water samples by wellbore fluid and ensure the representativeness of the samples taken.

[0053] It should be noted that in some embodiments, step S120 may include: S121, performing precipitation and filtration treatment on the tight gas reservoir test produced water samples to obtain the filtered tight gas reservoir test produced water samples; S122, based on the preset ambient temperature, collecting data on the filtered tight gas reservoir test produced water samples through a chloride ion sensor to obtain preliminary chloride ion concentration parameters; S123, based on the preset ambient temperature, collecting data on the filtered tight gas reservoir test produced water samples through a conductivity sensor to obtain conductivity parameters; S124, integrating the preliminary chloride ion concentration parameters and the conductivity parameters to determine the chloride ion concentration parameters of the formation water samples.

[0054] In this embodiment, the formation water samples in the heat-insulated and pressure-maintained sample cylinder are placed in laboratory experimental vessels. Then, the vessels containing the formation water samples are placed for 24 hours to separate some impurities such as sediment and oil stains in the samples using the principle of precipitation to ensure the purity of the formation water. 200 mL of formation water is taken out from the vessel, and an air conditioner is used to ensure that the laboratory measurement ambient temperature is stable at 26 degrees. Data is collected simultaneously using a chloride ion sensor and a conductivity sensor. The chloride ion sensor can directly obtain the chloride ion concentration parameters, and the conductivity sensor can obtain the conductivity parameters of the formation water sample to be measured. The chloride ion concentration can also be obtained through conversion. The data measured by the two sensors are calibrated with each other to ensure the accuracy and reliability of the chloride ion concentration parameters.

[0055] S200, select the regional gas-water ratio calculation model coefficients and construct a gas-water ratio parameter prediction model;

[0056] It should be noted that in some embodiments, step S200 may include: S210, select the regional gas-water ratio calculation model coefficients; S220, obtain the tight gas production data of several horizons in the tight gas reservoir to determine the gas-water ratio parameters of the horizons; S230, obtain the formation water samples of several horizons in the tight gas reservoir to determine the chloride ion concentration data of the formation water of the horizons; S240, use the gas-water ratio parameters of the horizons as the abscissa and the chloride ion concentration data of the formation water of the horizons as the ordinate to construct a relationship graph between the gas-water ratio and the chloride ion concentration value of the test produced water; S250, based on the relationship graph between the gas-water ratio and the chloride ion concentration value of the test produced water, introduce the regional gas-water ratio calculation model coefficients to construct a gas-water ratio parameter prediction model.

[0057] Among them, the regional gas-water ratio calculation model coefficients include the first control index parameter and the second control index parameter, and the regional gas-water ratio calculation model coefficients are determined through regional tight gas tests.

[0058] In some specific embodiments, the coefficients a and b of the regional gas-water ratio calculation model are selected, and their values are related to sedimentary environment factors. When the sedimentary environment is marine, the values of a and b conforming to the embodiments of the present invention can be determined through regional production data.

[0059] Specifically, as Figure 3 shown, there are 10 sets of production data of tight gas in existing horizons of a certain tight gas reservoir. Through the production data, the gas-water ratio parameters of this horizon can be obtained. At the same time, formation water samples of this section are obtained through sampling equipment, and the chloride ion concentration data of the formation water corresponding to this section are obtained through laboratory analysis. A relationship diagram between the gas-water ratio and the measured chloride ion concentration value of produced water is made. It can be seen from the figure that a = 2.5×10 9 , b = -0.0032.

[0060] Therefore, the expression of the gas-water ratio parameter prediction model in the embodiments of the present invention is specifically as follows:

[0061] GW = a×e (b×CL)

[0062] In the above formula, GW represents the gas-water ratio parameter, a and b represent the coefficients of the regional gas-water ratio calculation model, e represents the natural logarithm base, and CL represents the chloride ion concentration parameter of the formation water sample.

[0063] S300. Perform gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir;

[0064] It should be noted that in some embodiments, step S300 may include: S310. Input the chloride ion concentration parameter of the formation water sample into the gas-water ratio parameter prediction model; S320. Perform exponential calculation prediction processing on the chloride ion concentration parameter of the formation water sample to obtain the gas-water ratio parameter of the tight gas reservoir.

[0065] In some specific embodiments, several sample data of the tight gas reservoir section for which the gas-water ratio parameter is to be determined are obtained; the sample data includes the chloride ion concentration of the formation water; the chloride ion concentration data is input into the gas-water ratio parameter prediction model, and the values of the coefficients a and b of the regional gas-water ratio prediction model are substituted into the gas-water ratio parameter prediction model, and then the gas-water ratio parameter of this tight gas reservoir section can be calculated. Finally, the predicted gas-water ratio result is output and stored for use in the evaluation of the tight gas reservoir reserves and the formulation of the development implementation plan by users.

[0066] Furthermore, the embodiments of the present invention are illustrated through experiments, as Figure 4As shown in the figure, it is a well in a tight gas reservoir. The porosity of the reservoir section is 8%, and the permeability is 0.05 mD. The well is interpreted as a tight gas reservoir by logging. Drill stem testing is carried out in the gas reservoir section of 4100 - 4175 m. After perforation, formation water is produced in the gas reservoir section. Due to the water lock effect, the production of formation gas is not high. If the gas - water ratio parameter is calculated through the gas production and water production obtained from the test, it will inevitably lead to inaccurate gas - water ratio parameters. By sampling and analyzing the formation water through the aforementioned step S100, the chloride ion concentration of the formation water is obtained as 5000 ppm, and substituting it into the gas - water ratio parameter prediction model GW = a×e (b×CL) The calculated gas - water ratio is 281.3 m 3 / m 3 . Generally, fracturing is adopted in the development of tight gas to make the formation permeability better in order to produce more natural gas. Then, for example, more water will also be produced. Since the salinity of the water produced from the formation is relatively high, it generally cannot be directly discharged. A special water treatment device is required to treat the produced water to meet the standards before discharging. Therefore, the gas - water ratio parameter of the tight gas reservoir should be clarified in the development plan. Through the daily gas production and water production obtained from the reserve assessment, these two indicators are used as the control index parameters for the scale of some devices in the development process of the tight gas reservoir. Therefore, the gas - water ratio parameter is one of the core parameters in the design of the tight gas reservoir development plan.

[0067] In summary, the prediction of the gas - water ratio parameter in the tight gas reservoir test process provided by the embodiment of the present invention is based on the chloride ion concentration data of the water produced in the wellbore test, providing a fast and reliable method for calculating the gas - water ratio parameter in the tight gas reservoir test process for tight gas reservoir exploitation. Compared with related methods, the method for calculating the gas - water ratio parameter in the tight gas reservoir test process provided by the embodiment of the present invention has the following advantages:

[0068] 1) High - precision prediction results: The accuracy of the calculation results depends on the abundance of regional production data. With a large amount of well - testing data, the accuracy of the parameters a and b of the gas - water ratio calculation model can be improved. The calculation results of this method have higher accuracy compared with the prediction through logging data.

[0069] 2) Low cost: The production unit does not need to collect additional geological basic data, and there is no data collection operation cost. Only by processing and mining the existing geological data can the calculation of the gas - water ratio parameter be realized. This method has lower cost compared with the prediction through the trial production method.

[0070] Please refer to Figure 2 , the embodiment of the present application also provides a prediction system for the gas - water ratio parameter of a tight gas reservoir based on chloride ion concentration, which can implement the above - mentioned method for predicting the gas - water ratio parameter of a tight gas reservoir based on chloride ion concentration. The system includes:

[0071] The first module 201 is used to obtain the water - producing sample of the tight gas reservoir test and collect the chloride ion concentration data of the water sample to obtain the chloride ion concentration parameter of the formation water sample;

[0072] The second module 202 is configured to select the calculation model coefficients of the regional gas-water ratio and construct a prediction model for the gas-water ratio parameters.

[0073] The third module 203 is configured to perform gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas reservoir.

[0074] It can be understood that the content in the above method embodiments is applicable to the system embodiments of the present application. The functions specifically implemented in the system embodiments of the present application are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those in the above method embodiments.

[0075] The preferred embodiments of the embodiments of the present application have been described above with reference to the accompanying drawings, and thus do not limit the scope of the rights of the embodiments of the present application. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall fall within the scope of the rights of the embodiments of the present application.

Claims

1. A method for predicting gas-water ratio parameters of tight gas layers based on chloride ion concentration, characterized in that: The method comprises the following steps: Obtain water production samples from tight gas formations and collect chloride ion concentration data of water samples to obtain chloride ion concentration parameters of formation water samples; Select the regional gas-water ratio calculation model coefficients and build a gas-water ratio parameter prediction model, including: Select the regional gas-water ratio to calculate the model coefficients; Obtain tight gas production data of several layers of tight gas reservoirs and determine the gas-water ratio parameters of the layers; Obtain tight gas formation water samples from several layers of tight gas reservoirs and determine the chloride ion concentration data of the formation water; The gas-water ratio parameter of the layer is used as the horizontal coordinate, and the chloride ion concentration data of the formation water of the layer is used as the vertical coordinate to construct a relationship diagram between the gas-water ratio and the chloride ion concentration value of the test water production; Based on the relationship diagram between the gas-water ratio and the chloride ion concentration value of the test produced water, the regional gas-water ratio calculation model coefficient is introduced to construct the gas-water ratio parameter prediction model; The expression of the gas-water ratio parameter prediction model is specifically as follows: GW=a×e (b×CL) In the above formula, GW represents the gas-water ratio parameter, a and b represent the coefficients of the regional gas-water ratio calculation model, e represents the natural base, and CL represents the chloride ion concentration parameter of the formation water sample; Based on the gas-water ratio parameter prediction model, the chloride ion concentration parameter of the formation water sample is processed for gas-water ratio prediction to obtain the gas-water ratio parameter of the tight gas layer.

2. The method according to claim 1, characterized in that The method of obtaining a water production sample for testing a tight gas layer and collecting chloride ion concentration data of the water sample to obtain chloride ion concentration parameters of the formation water sample includes: Obtaining a test water production sample of the tight gas layer by using a downhole formation water in-situ sampler; The chloride ion concentration data of the water samples tested in the tight gas layer is collected to obtain the chloride ion concentration parameters of the formation water samples.

3. The method according to claim 2, characterized in that The method of obtaining the water production sample for testing the tight gas layer by using a downhole formation water in-situ sampler comprises: Identify the area to be studied; The downhole formation water in-situ sampler is lowered to the depth of the production layer section of the area to be studied to extract and process, so as to obtain a preliminary tight gas layer test water production sample; The preliminary dense gas layer test water production sample is transported and processed through a heat-insulating and pressure-maintaining sample tube to obtain the dense gas layer test water production sample.

4. The method according to claim 2, characterized in that: The method of collecting chloride ion concentration data of water samples from the tight gas formation test water production sample to obtain the chloride ion concentration parameters of the formation water sample includes: Performing sedimentation and filtration treatment on the dense gas layer test water production sample to obtain a filtered dense gas layer test water production sample; Based on the preset ambient temperature, the chloride ion sensor is used to collect data on the water production sample of the filtered dense gas layer test to obtain preliminary chloride ion concentration parameters; Based on the preset ambient temperature, data of the filtered dense gas layer test water production sample is collected by a conductivity sensor to obtain conductivity parameters; The preliminary chloride ion concentration parameter and the conductivity parameter are integrated to determine the chloride ion concentration parameter of the formation water sample.

5. The method according to claim 1, characterized in that The regional gas-water ratio calculation model coefficient includes a first control index parameter and a second control index parameter, and the regional gas-water ratio calculation model coefficient is determined by regional tight gas testing.

6. The method according to claim 1, characterized in that The gas-water ratio prediction processing is performed on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas layer, including: Inputting the chloride ion concentration parameter of the formation water sample into the gas-water ratio parameter prediction model; The chloride ion concentration parameter of the formation water sample is subjected to exponential calculation and prediction processing to obtain the gas-water ratio parameter of the tight gas layer.

7. The method according to claim 1, characterized in that The method also includes storing the gas-water ratio parameters of the tight gas layer for use in tight gas reservoir reserve evaluation and preparation of tight gas layer well development implementation plans.

8. A dense gas layer gas-water ratio parameter prediction system based on chloride ion concentration, characterized in that: The system comprises: The first module is used to obtain water production samples for testing of tight gas formations and collect data on chloride ion concentration of water samples to obtain chloride ion concentration parameters of formation water samples; The second module is used to select the regional gas-water ratio calculation model coefficients and build a gas-water ratio parameter prediction model, including: Select the regional gas-water ratio to calculate the model coefficients; Obtain tight gas production data of several layers of tight gas reservoirs and determine the gas-water ratio parameters of the layers; Obtain tight gas formation water samples from several layers of tight gas reservoirs and determine the chloride ion concentration data of the formation water; The gas-water ratio parameter of the layer is used as the horizontal coordinate, and the chloride ion concentration data of the formation water of the layer is used as the vertical coordinate to construct a relationship diagram between the gas-water ratio and the chloride ion concentration value of the test water production; Based on the relationship diagram between the gas-water ratio and the chloride ion concentration value of the test produced water, the regional gas-water ratio calculation model coefficient is introduced to construct the gas-water ratio parameter prediction model; The expression of the gas-water ratio parameter prediction model is specifically as follows: GW=a×e (b×CL) In the above formula, GW represents the gas-water ratio parameter, a and b represent the coefficients of the regional gas-water ratio calculation model, e represents the natural base, and CL represents the chloride ion concentration parameter of the formation water sample; The third module is used to perform gas-water ratio prediction processing on the chloride ion concentration parameter of the formation water sample based on the gas-water ratio parameter prediction model to obtain the gas-water ratio parameter of the tight gas layer.

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