Gas well multi-layer mining interlayer interference degree evaluation method

Abstract

The invention belongs to the technical field of gas reservoir development, and particularly relates to a gas well multi-layer mining interlayer interference degree evaluation method. The method comprises the steps of analyzing interlayer interference influence factors, performing historical fitting on a three-dimensional geology and numerical model, performing interference degree influence factor sensitivity analysis to obtain the influence of each parameter in different mining stages on the contribution rate, selecting parameters for evaluating the interference degree, and establishing an interference degree quantitative evaluation chart. And the established chart is applied to gas well multi-layer mining interlayer interference degree evaluation. According to the method, through the established commingling well interference degree evaluation chart, the purpose of quantitatively evaluating the contribution rate of the reservoir is achieved according to the formation pressure difference and the permeability difference of the upper reservoir and the lower reservoir. The method is simple to apply, and the contribution rate result of the small layer can be obtained by inquiring the chart after the formation pressure and permeability difference of the upper and lower reservoirs is obtained. Compared with an existing interference degree evaluation method, the reservoir contribution rate evaluation method can realize rapid and quantitative evaluation of the reservoir contribution rate.

Description

Technical Field

[0001] The invention belongs to the technical field of gas reservoir development, and in particular relates to a method for evaluating the degree of interlayer interference in multi-layer production of a gas well. Background Art

[0002] A gas reservoir usually has multiple gas-bearing strata. The single-well multi-layer commingled production method has been widely implemented in various oil and gas fields. For multi-layer oil and gas reservoirs with poor physical properties and small thickness, multi-layer commingled production has become an effective means of efficient development. In addition, the use of multi-layer commingled production to exploit low-permeability oil and gas reservoirs can not only improve the production capacity of a single well, but also improve the development benefits of the entire oil and gas field. However, considering that a gas reservoir usually has multiple gas-bearing strata, and the scale and connectivity of each layer, reservoir pressure, formation fluid, etc. are different, the production dynamic characteristics of the gas well under multi-layer commingled production are more complicated than those of single-layer production. Interlayer interference refers to the different gas production between reservoirs due to the non-uniform pressure system. For reservoirs with strong interlayer heterogeneity, interlayer interference will occur between multiple layers during commingled production. In the early stage of production, the high permeability layer will flow back to the low permeability layer through the wellbore, thereby affecting the production of the low permeability layer, resulting in the commingled production being lower than the sum of the production of each small layer. Implementing multi-layer commingled production in a single well and clarifying the inter-layer interference and gas supply characteristics of a single gas layer during multi-layer commingled production are of great significance for the efficient development of gas reservoirs, improving the horizontal and vertical utilization of reservoirs, and stabilizing production capacity and recovery rate.

[0003] At present, the research on the gas supply capacity of multi-layer commingled production is mainly based on production logging, well test analysis and indoor physical simulation experiments. Production logging is mainly evaluated by gas production profile testing. Usually, magnetic positioning, natural gamma, well temperature, fluid density, fluid pressure, continuous flow rate and water holdup test are carried out under normal production conditions of gas wells. The gas and water production of each perforated section are calculated by using gas production profile interpretation software, and finally the gas production profile of the well is provided. Well test analysis adopts the well test analysis method. Starting from the gas reservoir well test theory, a mathematical model of multi-layer commingled production gas reservoir seepage is established in combination with stratified well test data, and the bottom hole pressure, production contribution and influencing factors of multi-layer commingled production gas wells are studied. Indoor physical simulation experiments generally combine cores with different physical properties in parallel, and design multi-layer commingled production physical experiments to study the influence of reservoir physical property differences, gas well production allocation and other factors on the seepage characteristics, gas production contribution and recovery rate of each layer. Through solenoid valves, mass flow meters, pressure sensors and control switches, the purpose of monitoring the pressure changes and gas production contributions of each layer is achieved.

[0004] In summary, the current research on the gas supply capacity of multi-layer commingled production is affected by many factors, such as timeliness, representativeness of core samples, testing costs and time. It is difficult to meet the needs of quickly and quantitatively evaluating the degree of interlayer interference in low-permeability and tight gas reservoirs with a large number of gas wells, strong reservoir heterogeneity, and insufficient well testing data. Summary of the invention

[0005] The present invention provides a method for evaluating the degree of interlayer interference in multi-layer production of gas wells, and aims to provide an analysis method for quantitatively evaluating the degree of interlayer interference by determining the main influencing factors of interlayer interference through numerical simulation based on the actual production of gas wells in gas fields.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for evaluating the interference degree between layers in multi-layer production of a gas well comprises the following steps:

[0008] Step 1: Analysis of factors affecting inter-layer interference

[0009] Select effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameters to establish a three-dimensional geological and numerical model;

[0010] Step 2: History matching of 3D geological and numerical models

[0011] Combined with the historical production data of the gas reservoir, the three-dimensional geological and numerical models obtained in step 1 are fitted;

[0012] Step 3: Conduct sensitivity analysis on the factors affecting the degree of interference and obtain the influence of various parameters on the contribution rate at different mining stages;

[0013] Step 4: Select parameters for evaluating the degree of interference;

[0014] Step 5: Establish a quantitative evaluation chart for the degree of interference;

[0015] Step 6: Apply the chart created in step 5 to evaluate the degree of interference between layers in multi-layer production of gas wells.

[0016] The specific method for establishing the three-dimensional geological and numerical model in the step 1 is to input the effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameter data into the three-dimensional geological modeling software of the numerical model to establish a numerical model consistent with the actual situation.

[0017] The numerical model three-dimensional geological modeling software adopts eclipse software.

[0018] The specific fitting method in the step 2 is to simulate the calculation of daily gas production and wellhead pressure data through eclipse digital model software on the basis of the three-dimensional geological and numerical model established in step 1, and modify the model permeability and geological reserve parameters according to the gap between the actual daily gas production and wellhead pressure data of the gas well and the model calculation results, so that the daily gas production and wellhead pressure calculated by the model are consistent with the actual daily gas production and wellhead pressure data. At this time, the numerical model is a reliable numerical model and the fitting is completed.

[0019] The method for modifying the model permeability and geological reserve parameters is to continuously change the input values ​​of the permeability and geological reserve in the numerical model until a result closest to the actual production data is obtained.

[0020] The method for performing sensitivity analysis of interference degree influencing factors in the step 3 is to obtain a reliable numerical model, calculate the ratio of the low-pressure reservoir production contribution rate to the basic model by changing the ratio of permeability, formation pressure, wellhead production, geological reserves and the basic model, and thus evaluate the sensitivity of each parameter.

[0021] The method for calculating the ratio of the low-pressure reservoir production contribution rate to the basic model is to predict the gas production of each small layer through a numerical model, and obtain multiple low-pressure reservoir production contribution rates by changing one, two or more of the permeability, formation pressure, wellhead production or geological reserves; and calculate the ratio of each low-pressure reservoir production contribution rate to the basic model production contribution rate, that is, to obtain the ratio of each low-pressure reservoir production contribution rate to the basic model.

[0022] The parameters selected in step 4 for evaluating the interference degree are initial production, production after one year and EUR.

[0023] The specific method for establishing the quantitative evaluation chart of the interference degree in the step five is as follows: on the basis of obtaining a reliable numerical model, by changing the two parameters of permeability and formation pressure difference in the model, the production contribution rate of the low-pressure reservoir under different pressure differences and different permeability multiples is obtained, thereby establishing a production contribution chart after one month of mining, a production contribution chart after one year of mining, and a production contribution chart at the end of the forecast period.

[0024] Beneficial effects:

[0025] (1) The present invention adopts six steps, namely, analyzing the influencing factors of interlayer interference, performing historical fitting on three-dimensional geological and numerical models, performing sensitivity analysis on the influencing factors of interference degree to obtain the influence of various parameters on the contribution rate at different production stages, selecting parameters for evaluating the interference degree, establishing a quantitative evaluation chart for the interference degree, and applying the established chart to the evaluation of the interlayer interference degree in multi-layer production of gas wells. Based on the actual production of gas fields and gas wells, the main influencing factors of interlayer interference are determined, thereby obtaining an analytical method for quantitatively evaluating the degree of interlayer interference.

[0026] (2) The present invention achieves the purpose of quantitatively evaluating the reservoir contribution rate by establishing a combined production well interference degree evaluation chart based on the formation pressure difference and permeability difference between the upper and lower reservoirs.

[0027] (3) The present invention is simple to apply. After obtaining the formation pressure and permeability difference of the upper and lower reservoirs, the contribution rate result of the small layer can be obtained by querying the chart.

[0028] (4) Compared with the existing interference degree evaluation method, the present invention can realize rapid and quantitative evaluation of reservoir contribution rate.

[0029] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a flow chart of the present invention.

[0032] Figure 2 It is a three-dimensional grid diagram of the numerical model in a specific embodiment of the present invention.

[0033] Figure 3 It is the upper reservoir gas well pulling together production curve in the specific embodiment of the present invention.

[0034] Figure 4 It is the lower reservoir gas well pulling production curve in the specific embodiment of the present invention.

[0035] Figure 5 It is the fitting result of the wellhead pressure of the upper reservoir gas well in the specific embodiment of the present invention.

[0036] Figure 6 It is the fitting result of the wellhead pressure of the lower reservoir gas well in the specific embodiment of the present invention.

[0037] Figure 7 It is a schematic diagram of the interference degree of the permeability multiple on the initial daily gas production in a specific embodiment of the present invention.

[0038] Figure 8 It is a schematic diagram of the interference degree of the permeability multiple on the daily gas production after one year in a specific embodiment of the present invention.

[0039] Fig. 9 It is a schematic diagram of the interference degree of the permeability multiple on the cumulative output in the forecast period in a specific embodiment of the present invention.

[0040] Fig.10It is a schematic diagram of the interference degree of formation pressure difference on initial daily gas production in a specific embodiment of the present invention.

[0041] Fig.11 It is a schematic diagram of the interference degree of formation pressure difference on daily gas production one year later in a specific embodiment of the present invention.

[0042] Fig.12 It is a schematic diagram of the interference degree of formation pressure difference on the cumulative production during the prediction period in a specific embodiment of the present invention.

[0043] Fig.13 It is a schematic diagram of the interference degree of the wellhead production on the initial daily gas production in a specific embodiment of the present invention.

[0044] Fig.14 It is a schematic diagram of the interference degree of the wellhead production on the daily gas production one year later in a specific embodiment of the present invention.

[0045] Fig.15 It is a schematic diagram of the interference degree of the wellhead production on the cumulative production in the forecast period in a specific embodiment of the present invention.

[0046] Fig.16 It is a schematic diagram of the interference degree of geological reserves on the initial daily gas production in a specific embodiment of the present invention.

[0047] Fig.17 It is a schematic diagram of the interference degree of geological reserves on daily gas production one year later in a specific embodiment of the present invention.

[0048] Fig.18 It is a schematic diagram of the interference degree of geological reserves on the cumulative output in the forecast period in a specific embodiment of the present invention.

[0049] Fig.19 It is a schematic diagram of sensitivity analysis of the impact of initial daily gas production in a specific embodiment of the present invention.

[0050] Fig. 20 This is a sensitivity analysis of the impact of daily gas production after one year in a specific embodiment of the present invention.

[0051] Fig.21 It is a sensitivity analysis of the impact degree of the cumulative output at the end of the forecast period in a specific embodiment of the present invention.

[0052] Fig. 22 This is a chart showing the contribution of the lower layer production after one month of mining in a specific embodiment of the present invention.

[0053] Fig.23 This is a chart showing the contribution of the lower layer production after one year of mining in a specific embodiment of the present invention.

[0054] Fig.24 It is a chart showing the contribution of the lower layer output at the end of the forecast period in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Embodiment 1:

[0057] according to Figure 1 A method for evaluating the interference degree between layers in a gas well multi-layer production is shown, comprising the following steps:

[0058] Step 1: Analysis of factors affecting inter-layer interference

[0059] Select effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameters to establish a three-dimensional geological and numerical model;

[0060] Step 2: History matching of 3D geological and numerical models

[0061] Combined with the historical production data of the gas reservoir, the three-dimensional geological and numerical models obtained in step 1 are fitted;

[0062] Step 3: Conduct sensitivity analysis on the factors affecting the degree of interference and obtain the influence of various parameters on the contribution rate at different mining stages;

[0063] Step 4: Select parameters for evaluating the degree of interference;

[0064] Step 5: Establish a quantitative evaluation chart for the degree of interference;

[0065] Step 6: Apply the chart created in step 5 to evaluate the degree of interference between layers in multi-layer production of gas wells.

[0066] The invention achieves the purpose of quantitatively evaluating the reservoir contribution rate by finally establishing the combined production well interference degree evaluation chart according to the formation pressure difference and permeability difference of the upper and lower reservoirs. The invention is simple to apply. After obtaining the formation pressure and permeability difference of the upper and lower reservoirs, the contribution rate result of the small layer can be obtained by querying the chart.

[0067] The parameters for evaluating the degree of interference selected in step 4 of this embodiment provide a basis for establishing in step 5 a quantitative evaluation chart of the degree of interference, including a chart of production contribution after one month of mining, a chart of production contribution after one year of mining, and a chart of production contribution at the end of the forecast period.

[0068] Compared with the existing interference degree evaluation method, the present invention can realize rapid and quantitative evaluation of reservoir contribution rate.

[0069] Embodiment 2:

[0070] according to Figure 1 The method for evaluating the degree of interlayer interference in multi-layer production of a gas well shown in the embodiment is different from that of Example 1 in that the specific method for establishing a three-dimensional geological and numerical model in the step 1 is to input the effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameter data into the three-dimensional geological modeling software of the numerical model to establish a numerical model that is consistent with the actual situation.

[0071] Furthermore, the numerical model three-dimensional geological modeling software adopts eclipse software.

[0072] In actual use, the three-dimensional geological and numerical models established by combining the above method with the physical property data of gas reservoirs lay the foundation for the evaluation of the degree of interlayer interference in multi-layer production of gas wells.

[0073] Embodiment three:

[0074] according to Figure 1 The method for evaluating the degree of interlayer interference in multi-layer production of a gas well shown in the embodiment is different from that of Example 1 in that the specific fitting method in the step 2 is to simulate the calculation of daily gas production and wellhead pressure data through eclipse digital model software on the basis of the three-dimensional geological and numerical model established in step 1, and according to the gap between the actual daily gas production and wellhead pressure data of the gas well and the model calculation results, the model permeability, geological reserve parameters, etc. are modified to make the daily gas production and wellhead pressure calculated by the model consistent with the actual daily gas production and wellhead pressure data. At this time, the numerical model is a reliable numerical model and the fitting is completed.

[0075] Furthermore, the method for modifying the model permeability and geological reserve parameters is to continuously change the input values ​​of the permeability and geological reserve in the numerical model until a result closest to the actual production data is obtained.

[0076] Furthermore, the method for modifying the model permeability and geological reserve parameters is to obtain the result closest to the actual production data by changing the values ​​of the permeability and geological reserve in the numerical model.

[0077] In actual use, this technical solution, based on the establishment of numerical simulation, combined with the historical data of gas reservoir production, carried out historical fitting and obtained a reliable numerical model to provide support for subsequent model prediction and interference degree analysis.

[0078] In specific applications, there are many parameters that can be modified and adjusted in the model adjustment, and permeability and geological reserves are the two main parameters. When modifying permeability and geological reserves, the value obtained in step 1 is used as the basic value, and floating values ​​are selected above and below the basic value.

[0079] Embodiment 4:

[0080] according to Figure 1 The method for evaluating the degree of interference between layers in multi-layer production of a gas well shown in the embodiment is different from that in Example 1 in that: the method for sensitivity analysis of factors affecting the degree of interference in the step three is to obtain a reliable numerical model, and by changing the ratio of permeability, formation pressure, wellhead production, geological reserves and the basic model, calculate the ratio of the low-pressure reservoir production contribution rate to the basic model, thereby evaluating the sensitivity of each parameter.

[0081] Furthermore, the method for calculating the ratio of the low-pressure reservoir production contribution rate to the basic model is to predict the gas production of each small layer through a numerical model, and obtain multiple low-pressure reservoir production contribution rates by changing one, two or more of the permeability, formation pressure, wellhead production or geological reserves; and calculate the ratio of each low-pressure reservoir production contribution rate to the basic model production contribution rate, that is, to obtain the ratio of each low-pressure reservoir production contribution rate to the basic model.

[0082] In actual use, a reliable numerical model refers to a numerical model in which the daily gas production and wellhead pressure calculated by the model are consistent with the actual daily gas production and wellhead pressure data.

[0083] When evaluating the sensitivity of each parameter, by drawing the percentage of permeability, formation pressure, wellhead production, geological reserves change and the percentage of low-pressure reservoir production contribution, the sensitivity of permeability, formation pressure, wellhead production, and geological reserves parameters can be evaluated, thereby determining the first two parameters with the greatest impact. By conducting a sensitivity analysis of the factors affecting the degree of interference, it was concluded that the influence of various parameters on the contribution rate at different mining stages was different, laying the foundation for the subsequent quantitative evaluation chart of the degree of interference.

[0084] The following conclusions were drawn through analysis: in the initial stage of exploitation, formation pressure > permeability > geological reserves > wellhead production; in the final stage of exploitation, geological reserves > formation pressure > permeability > wellhead production.

[0085] Embodiment five:

[0086] according to Figure 1 The method for evaluating the interference degree between layers in multi-layer production of a gas well shown in the figure is different from that in the first embodiment in that the parameters selected in the fourth step for evaluating the interference degree are the initial production, the production after one year and the EUR.

[0087] Because the main indicators for evaluating gas well production capacity in China's petroleum and industry currently include: initial production, production after one year and EUR. In the present invention, initial production, production after one year and EUR are used as parameters for evaluating the degree of interference, which fully reflects the principles of simplicity, comprehensiveness and practicality, and is highly consistent with the actual current gas well evaluation system, and is more practical.

[0088] Among them, EUR in Chinese means the ultimate recoverable reserves of the gas well.

[0089] Embodiment six:

[0090] according to Figure 1 The method for evaluating the degree of interference between layers in multi-layer production of a gas well shown in the embodiment is different from that of Example 1 in that: the specific method for establishing a quantitative evaluation chart of the degree of interference in the step five is: on the basis of obtaining a reliable numerical model, by changing the two parameters of permeability and formation pressure difference in the model, the production contribution rate of the low-pressure reservoir under different pressure differences and different permeability multiples is obtained, thereby establishing a production contribution chart after one month of production, a production contribution chart after one year of production, and a production contribution chart at the end of the forecast period.

[0091] In actual use, the establishment of the interference degree quantitative evaluation chart enables the present invention to achieve the purpose of quantitatively evaluating the reservoir contribution rate according to the formation pressure difference and permeability difference between the upper and lower reservoirs.

[0092] Embodiment seven:

[0093] Reference Figure 1-Figure 24 , a method for evaluating the interference degree between layers in multi-layer production of a gas well, comprising the following steps:

[0094] Step 1: Numerical model establishment

[0095] According to the physical property data of the upper and lower reservoirs of the gas field, combined with the upper reservoir gas well pulling together the production curve (such as Figure 3 As shown) and the lower reservoir gas well pull production curve (as shown Figure 4 ), obtain the production data of the upper reservoir gas wells and the lower reservoir gas wells, and establish the gas reservoir geological model, such as Figure 2 shown.

[0096] Step 2: Perform history matching

[0097] On the basis of establishing the numerical model, the auxiliary history matching software is used to carry out history matching. The history matching used in this embodiment is the Schlumberger auxiliary history matching module, so as to obtain a reliable numerical model to provide support for the later model prediction and interference degree analysis. Through fitting, the fitting result of the wellhead pressure of the upper reservoir gas well is obtained (such as Figure 5 ) and the fitting results of the wellhead pressure of the lower reservoir gas well (as shown in Figure 6), the upper reservoir gas well wellhead pressure fitting results and the lower reservoir gas well wellhead pressure fitting results are the optimal fitting model results obtained by simulation after multiple sets of auxiliary historical fitting.

[0098] Step 3: Sensitivity analysis of influencing factors

[0099] Permeability difference, formation pressure difference, wellhead production, and geological reserves were selected as influencing factors to predict the strength of interlayer interference under different conditions. The research results show that the contribution rate of the lower layer shows different characteristics at different mining stages. In the early stage of mining: formation pressure> permeability> geological reserves> open flow ratio; in the late stage of mining: geological reserves> formation pressure> permeability> open flow ratio. Figure 7-Figure 21 shown.

[0100] Among them, the permeability multiple has an impact on the initial daily gas production. Figure 7 As shown in the figure, it can be seen that after one month of production, the permeability multiples of different models and the basic model and the ratio of the contribution rate of low-pressure reservoir production continue to increase with the increase of the multiples.

[0101] The permeability multiple has an impact on the daily gas production after one year. Figure 8 As shown in the figure, it can be seen that after one year of production, the permeability multiples of different models and the basic model and the ratio of the contribution rate of low-pressure reservoir production increase significantly when the multiples are set between 0 and 1. Subsequently, the ratio of the contribution rate of low-pressure reservoir production tends to be stable as the multiples increase.

[0102] The degree of interference of the permeability multiple on the cumulative production during the forecast period is as follows: Fig. 9 As shown in the figure, it can be seen that at the end of the production period, the permeability multiples of different models and the basic model and the ratio of the low-pressure reservoir production contribution rate increase with the increase of the multiples.

[0103] The degree of interference of formation pressure difference on initial daily gas production is as follows: Fig.10 As shown in the figure, it can be seen that after one month of production, the ratio of the formation pressure difference multiples of different models to the basic model and the ratio of the low-pressure reservoir production contribution rate increases with the increase of the multiples.

[0104] The degree of interference of formation pressure difference on daily gas production after one year is as follows: Fig.11 As shown in the figure, it can be seen that after one year of production, the formation pressure difference multiples of different models and the basic model and the ratio of the low-pressure reservoir production contribution rate increase linearly.

[0105] The degree of interference of formation pressure difference on the cumulative production during the forecast period is as follows: Fig.12As shown in the figure, it can be seen that at the end of the production period, the ratio of the formation pressure difference multiples of different models and the basic model to the low-pressure reservoir production contribution rate increases with the increase of the multiples.

[0106] The degree of interference of wellhead production on initial daily gas production is as follows: Fig.13 As shown in the figure, it can be seen that after one month of production, the ratio of the wellhead production multiples and the low-pressure reservoir production contribution rate of different models and the basic model shows that as the multiples increase, the ratio of the low-pressure reservoir production contribution rate continues to decrease.

[0107] The degree of interference of wellhead production on daily gas production one year later is as follows: Fig.14 As shown in the figure, it can be seen that after one year of production, the ratio of the wellhead production multiples and the low-pressure reservoir production contribution rate of different models and the basic model shows that as the multiples increase, the ratio of the low-pressure reservoir production contribution rate continues to decrease.

[0108] The degree of interference of wellhead production on the cumulative production during the forecast period is as follows: Fig.15 As shown in the figure, it can be seen that at the end of the production period, the ratio of the wellhead production multiples and the low-pressure reservoir production contribution rate of different models and the basic model has a slight upward trend in the early stage of the multiple change, and then tends to be stable.

[0109] The degree of interference of geological reserves on initial daily gas production is as follows: Fig.16 As shown in the figure, it can be seen that after one month of production, when the geological reserve multiples of different models and the basic model and the ratio of the low-pressure reservoir production contribution rate increase in the range of 0.2-0.4, the ratio of the low-pressure reservoir production contribution rate increases rapidly, and then tends to be stable.

[0110] The degree of interference of geological reserves on daily gas production one year later is as follows: Fig.17 As shown in the figure, it can be seen that after one year of production, the ratio of geological reserves multiples to low-pressure reservoir production contribution rate of different models and the basic model increases with the increase of the multiples.

[0111] The degree of interference of geological reserves on the cumulative production during the forecast period is as follows: Fig.18 As shown in the figure, it can be seen that at the end of the production period, the ratio of the geological reserves multiples of different models to the basic model to the low-pressure reservoir production contribution rate increases with the increase of the multiples.

[0112] Sensitivity analysis of the impact of initial daily gas production Fig.19As shown in the figure, it can be seen that the relationship between the ratio of the initial daily gas production (after one month of production) of different models and the basic model and the ratio of the low-pressure reservoir production contribution rate is determined, thereby determining the sensitivity of changes in permeability, formation pressure, wellhead production and geological reserve parameters to the low-pressure reservoir production contribution rate. From this figure, the change trend of the formation pressure parameter is quite obvious, and it is concluded that the formation pressure is the most sensitive parameter.

[0113] Sensitivity analysis of the impact of daily gas production after one year Fig. 20 As shown in the figure, it can be seen that the relationship between the daily gas production ratio of different models and the basic model after one year and the ratio of the low-pressure reservoir production contribution rate can be determined, so as to determine the sensitivity of the change of this parameter to the low-pressure reservoir production contribution rate. In this figure, the change trend of the formation pressure parameter is relatively obvious compared with the changes of other parameters, and it is concluded that the formation pressure is the most sensitive parameter.

[0114] The sensitivity analysis of the impact of cumulative output at the end of the forecast period is as follows: Fig.21 As shown in the figure, it can be seen that the relationship between the ratio of the cumulative production at the end of the forecast period of different models and the basic model and the ratio of the contribution rate of low-pressure reservoir production can be determined from this figure. It is more sensitive to determine the geological reserves.

[0115] Step 4: Selection of interference degree evaluation parameters

[0116] At present, the main indicators for evaluating gas well production capacity in China's oil and gas industry include: initial production, production after one year and EUR. Therefore, based on the principles of simplicity, comprehensiveness and practicality, three parameters are selected as the method for evaluating the degree of interference.

[0117] Step 5: Create an interference evaluation chart

[0118] On the basis of sensitivity analysis and combined with the selection results of interference degree evaluation parameters, a quantitative evaluation chart of interference degree under the dual control conditions of formation pressure difference and permeability difference was established.

[0119] The chart of the contribution of the lower layer production after one month of mining is shown in the figure below. Fig. 22 As shown in the figure, it can be seen that under different formation pressure difference conditions between the upper and lower reservoirs, by querying the multiple ratio relationship of different permeabilities of the upper and lower reservoirs, the contribution rate of the low-pressure reservoir production after one month of mining can be quickly determined.

[0120] The chart of the contribution of the lower layer production after one year of mining is shown in the figure below. Fig.23 As shown in the figure, it can be seen that under different formation pressure difference conditions between the upper and lower reservoirs, by querying the multiple ratio relationship of different permeabilities of the upper and lower reservoirs, the contribution rate of the low-pressure reservoir production after one year of exploitation can be quickly determined.

[0121] The chart of the contribution of lower-level production at the end of the forecast period is as follows: Fig.24As shown in the figure, it can be seen that under different formation pressure difference conditions between the upper and lower reservoirs, by querying the multiple ratio relationship of different permeabilities of the upper and lower reservoirs, the contribution rate of the low-pressure reservoir production at the end of the prediction period can be quickly determined.

[0122] In the absence of conflicts, technicians in this field can combine the relevant technical features in the above examples according to actual conditions to achieve corresponding technical effects. The specific combinations are not described here one by one.

[0123] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0124] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0125] The above are only preferred embodiments of the present invention. The present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for evaluating the degree of interference between layers in multi-layer production of a gas well, characterized by: The following steps are included: Step 1: Analysis of factors affecting inter-layer interference Select effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameters to establish a three-dimensional geological and numerical model; Step 2: History matching of 3D geological and numerical models Combined with the historical production data of the gas reservoir, the three-dimensional geological and numerical models obtained in step 1 are fitted; Step 3: Conduct sensitivity analysis on the factors affecting the degree of interference and obtain the influence of various parameters on the contribution rate at different mining stages; Step 4: Select parameters for evaluating the degree of interference; Step 5: Establish a quantitative evaluation chart for the degree of interference; Step 6: Apply the chart created in step 5 to evaluate the degree of interference between layers in multi-layer production of gas wells.

2. A method for evaluating the degree of interference between layers in multi-layer production of a gas well as claimed in claim 1, characterized in that: The specific method for establishing the three-dimensional geological and numerical model in the step 1 is to input the effective thickness, permeability, gas saturation, porosity, formation pressure and formation temperature parameter data into the three-dimensional geological modeling software of the numerical model to establish a numerical model consistent with the actual situation.

3. A method for evaluating the degree of interference between layers in multi-layer production of a gas well as claimed in claim 2, characterized in that: The numerical model three-dimensional geological modeling software adopts eclipse software.

4. The method for evaluating the degree of interference between layers in multi-layer production of a gas well according to claim 1, characterized in that: The specific fitting method in the step 2 is to simulate the calculation of daily gas production and wellhead pressure data through eclipse digital model software on the basis of the three-dimensional geological and numerical model established in step 1, and modify the model permeability and geological reserve parameters according to the gap between the actual daily gas production and wellhead pressure data of the gas well and the model calculation results, so that the daily gas production and wellhead pressure calculated by the model are consistent with the actual daily gas production and wellhead pressure data. At this time, the numerical model is a reliable numerical model and the fitting is completed.

5. A method for evaluating the degree of interference between layers in multi-layer production of a gas well as claimed in claim 4, characterized in that: The method for modifying the model permeability and geological reserve parameters is to continuously change the input values ​​of the permeability and geological reserve in the numerical model until a result closest to the actual production data is obtained.

6. A method for evaluating the degree of interference between layers in multi-layer production of a gas well as claimed in claim 1, characterized in that: The method for performing sensitivity analysis of interference degree influencing factors in the step 3 is to obtain a reliable numerical model, calculate the ratio of the low-pressure reservoir production contribution rate to the basic model by changing the ratio of permeability, formation pressure, wellhead production, geological reserves and the basic model, and thus evaluate the sensitivity of each parameter.

7. A method for evaluating the degree of interference between layers in multi-layer production of a gas well as claimed in claim 6, characterized in that: The method for calculating the ratio of the low-pressure reservoir production contribution rate to the basic model is to predict the gas production of each small layer through a numerical model, and obtain multiple low-pressure reservoir production contribution rates by changing one, two or more of the permeability, formation pressure, wellhead production or geological reserves; and calculate the ratio of each low-pressure reservoir production contribution rate to the basic model production contribution rate, that is, to obtain the ratio of each low-pressure reservoir production contribution rate to the basic model.

8. The method for evaluating the degree of interference between layers in multi-layer production of a gas well according to claim 1, characterized in that: The parameters selected in step 4 for evaluating the interference degree are initial production, production after one year and EUR.

9. The method for evaluating the degree of interference between layers in multi-layer production of a gas well according to claim 1, characterized in that: The specific method for establishing the quantitative evaluation chart of the interference degree in the step five is as follows: on the basis of obtaining a reliable numerical model, by changing the two parameters of permeability and formation pressure difference in the model, the production contribution rate of the low-pressure reservoir under different pressure differences and different permeability multiples is obtained, thereby establishing a production contribution chart after one month of mining, a production contribution chart after one year of mining, and a production contribution chart at the end of the forecast period.

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