Fractured low-porosity sandstone gas reservoir water invasion early warning method, system, equipment and medium

Abstract

The invention belongs to the technical field of petroleum and natural gas development geology, and relates to a fractured low-porosity sandstone gas reservoir water invasion early warning method, which comprises the following steps of: acquiring static geological parameters and dynamic parameters which influence the fractured gas reservoir water invasion as evaluation indexes; determining a weight coefficient of each evaluation index; performing normalization processing on the evaluation indexes of different gas wells to obtain evaluation index parameters; based on the evaluation index parameters and the weight coefficient of each evaluation index, calculating the water invasion risk coefficient of each single well of the block by adopting a constructed mathematical model of the water invasion risk coefficient and the evaluation index; drawing a water invasion risk plane distribution diagram according to the water invasion risk coefficient of each single well in the block, and judging the water invasion risk; calculating the advancing speed of the near water body according to the water invasion risk coefficient; and predicting the future water breakthrough time of the gas well by adopting the prediction model based on the well spacing of the adjacent wells and the advancing speed of the adjacent water body. Quantitative evaluation of the crack non-uniform water invasion risk and accurate early warning of the gas well water breakthrough time are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas development geology, and relates to a water intrusion early warning method, system, equipment and medium for fractured low-porosity sandstone gas reservoirs. Background Art

[0002] In recent years, with the increasing maturity of the exploration and development of medium and shallow natural gas resources in my country, new exploration and discovery have become increasingly difficult. Deep / ultra-deep layers have gradually become an important area for natural gas exploration and development in my country, and important breakthroughs have been made in the ultra-deep layers of the Kuche Depression in the Tarim Basin, with the discovery of deep / ultra-deep gas fields such as Dabei, Keshen, and Bozi. The gas reservoir is buried at a depth of 6000-8000m, with high temperature, ultra-high pressure, dense matrix, and widespread development of fractures. The gas-water relationship is extremely complex, and the gas reservoir type and development difficulty are rare in the world. This type of gas reservoir has a multi-scale medium of "pore-fracture-fault" development, and the matrix and permeability difference is as high as 5-6 orders of magnitude. Formation water can easily form a high-speed water invasion channel along the fractures. The risk of non-uniform water invasion in gas reservoirs is increasing year by year. After water appears in the gas well, the production capacity drops rapidly, and even the well is flooded and closed. Non-uniform water invasion in fractures seriously affects the development effect and recovery rate of gas reservoirs. In order to formulate technical countermeasures for water control and management as early as possible and reduce the risk of water invasion in gas reservoirs, it is necessary to accurately predict the water breakthrough time of gas wells and quantitatively evaluate the risk of water invasion in gas reservoirs, so as to provide a reliable basis for adjusting development countermeasures and formulating water control measures. Water invasion early warning and quantitative evaluation have become key technical issues for water invasion control and efficient development of deep / ultra-deep fractured low-porosity sandstone edge-water gas reservoirs.

[0003] Through investigation, it is found that the current methods for early identification of water invasion in fractured gas reservoirs mainly include the use of wellhead pressure and production changes, analysis of produced water properties, pressure drop curve identification, unstable well test curve identification, material balance method water invasion identification and gas reservoir numerical simulation. These methods require the gas reservoir to have a long production time and recovery degree, and have certain limitations in application for ultra-deep fractured low-porosity sandstone gas reservoirs in the early stage of development. At the same time, they do not take into account the static characteristics of the gas reservoir itself, such as multi-scale media, high temperature, and ultra-high pressure.

[0004] Regarding fractured water string and water cone, relevant researchers have also done a lot of research work. It is generally believed that large fractures are the main channels for fractured water string and bottom water cone. A water cone height and shape model for bottom water gas reservoirs has been established. The cone model has been used to simulate the water invasion dynamics of gas wells in fractured bottom water gas reservoirs. Through sensitivity analysis of various parameters such as matrix permeability, fracture size and distribution, bottom well interlayer, gas production rate, gas well opening degree and water body size, it is found that water channeling along fractures is the main water invasion feature of this type of gas reservoir. Water invasion has a great impact on the production dynamics of gas wells. When there is no water invasion, there is no pressure supplement in the gas well, and the production dynamics of the gas well show the characteristics of closed gas reservoirs. In the early stage of water invasion, the gas well is supplemented by water body energy, and the pressure will drop slower than when there is no water invasion when the production is stable. In the middle and late stages of water invasion, especially when the edge and bottom water rushes into the vicinity of the gas well, the gas flow is obviously resisted, and the production pressure difference of the gas well increases significantly under the same production.

[0005] In terms of predicting the time of water breakthrough in gas wells and identifying the water invasion stage, Yang Furong et al. considered the influencing factors such as gas non-Darcy effect, gas-water mobility ratio, original bound water saturation, residual gas saturation, and the distance between the gas well and the edge water, and obtained the calculation formula for the water tongue breakthrough time of high-yield gas wells and edge water gas reservoirs through mathematical deduction. Li Yong et al. proposed a new method for dividing the water invasion stage of gas wells based on the changes in well gas production and pressure using three diagnostic curves drawn using the actual production and pressure data of gas wells. The production of gas wells can be divided into three stages through the three diagnostic curves: the non-water invasion period, the initial water invasion period, and the middle and late water invasion period. This method can be used to judge and analyze the actual wells on site, accurately identify the water invasion stage of gas wells, and determine the water breakthrough sequence of gas wells in water-bearing gas reservoirs. Luo Ruilan et al. used a modern gas well production dynamic analysis method to analyze the dynamic characteristics of water invasion in such gas reservoirs / gas wells, thereby establishing a water production early warning model. According to the characteristics of the change of gas production index of gas wells, the production of water-producing gas wells was divided into four stages: the well cleaning period, the non-water invasion period, the initial water invasion period, and the water production period. In the early stage of water invasion, the gas production index increases significantly due to energy replenishment, becoming a sign of water invasion warning. Once the water invasion breaks through the bottom of the well, the gas production index will decrease rapidly.

[0006] The above methods only divide water invasion stages and warn water invasion from the perspective of dynamic analysis of water invasion in gas reservoirs, without considering the actual geological characteristics of gas reservoirs and the structural location of gas wells. In addition, there is a lack of effective quantitative evaluation methods for water invasion. At the same time, due to the difficulty in collecting dynamic monitoring data of ultra-deep and high-pressure gas reservoirs, it is impossible to accurately predict the water breakthrough time of gas wells. Therefore, it is necessary to develop new technologies and methods to solve the shortcomings in the prediction of water breakthrough time of gas wells, and to achieve quantitative evaluation of water invasion risks in deep / ultra-deep fractured low-porosity sandstone gas reservoirs and accurate warning of water breakthrough time of gas wells. Summary of the invention

[0007] The purpose of the present invention is to provide a fractured low-porosity sandstone gas reservoir water intrusion early warning method, system, equipment and medium, which solves the problem that the existing method cannot accurately predict the water breakthrough time of the gas well.

[0008] The present invention is achieved through the following technical solutions:

[0009] The present invention discloses a water intrusion early warning method for fractured low-porosity sandstone gas reservoirs, comprising the following process:

[0010] Obtain static geological parameters and dynamic parameters that affect water invasion in fractured gas reservoirs as evaluation indicators;

[0011] Determine the weight coefficient of each evaluation indicator;

[0012] The evaluation indexes of different gas wells are normalized to obtain the evaluation index parameters;

[0013] Based on the evaluation index parameters and the weight coefficient of each evaluation index, the water invasion risk coefficient of each single well in the block is calculated using the constructed mathematical model of water invasion risk coefficient and evaluation index;

[0014] Draw a water invasion risk plane distribution map based on the water invasion risk coefficient of each single well in the block, and judge the water invasion risk based on the water invasion risk coefficient plane distribution map and the actual gas well production situation;

[0015] Calculate the advancing speed of the adjacent water body according to the water invasion risk coefficient;

[0016] Based on the spacing between adjacent wells and the advancing speed of the adjacent water body, the constructed prediction model is used to predict the future water breakthrough time of the gas well.

[0017] Furthermore, the static geological parameters include the water avoidance height H of the gas well, the distance L between the gas well and the edge water, the fracture mode F and the reservoir permeability K;

[0018] Dynamic parameters include gas production rate S.

[0019] Furthermore, there is a positive correlation between reservoir permeability K and water invasion, a negative correlation between the distance L between the gas well and the edge water and the size of the water avoidance height H of the gas well and water invasion; there is a positive correlation between gas production rate S and water invasion.

[0020] Furthermore, the mathematical model of the water intrusion risk coefficient and the evaluation index is:

[0021] ω=(aK+bF+cS-dH-eL)×100%;

[0022] Wherein, ω is the water invasion risk coefficient; K is the reservoir permeability; H is the water avoidance height of the gas well; L is the distance between the gas well and the edge water; S is the gas production rate of the gas reservoir in that month; F is the fracture mode; a, b, c, d, and e are the weight coefficients of the five evaluation indicators respectively.

[0023] Furthermore, the weight coefficients of the evaluation indicators are determined using the priority diagram method.

[0024] Furthermore, the evaluation indicators of different gas wells are normalized, and the normalization formula is:

[0025]

[0026] L′ x is the normalized evaluation index, L x is the actual value of a certain evaluation index, x=1........i, i is the number of evaluation indicators.

[0027] Furthermore, the calculation expression of the propulsion speed near the water body is:

[0028] Y=Aω(x) 2 -Bω(x)+C;

[0029] Y is the advancing speed of the adjacent water body, ω is the water intrusion risk coefficient, ω(x) represents the xth ω value; A, B, and C are coefficients, which are obtained based on the fitting of historical data.

[0030] The present invention also discloses a fractured low-porosity sandstone gas reservoir water intrusion early warning system, comprising:

[0031] Parameter acquisition module, used to obtain static geological parameters and dynamic parameters affecting water invasion of fractured gas reservoirs as evaluation indicators;

[0032] A weight coefficient determination module is used to determine the weight coefficient of each evaluation index;

[0033] An evaluation index normalization module is used to normalize the evaluation indexes of different gas wells to obtain evaluation index parameters;

[0034] The water invasion risk coefficient calculation module is used to calculate the water invasion risk coefficient of each single well in the block based on the evaluation index parameters and the weight coefficient of each evaluation index, using the constructed mathematical model of water invasion risk coefficient and evaluation index;

[0035] The chart drawing module is used to draw the water invasion risk plane distribution chart according to the water invasion risk coefficient of each single well in the block, and judge the water invasion risk according to the water invasion risk plane distribution chart and the actual gas well production situation;

[0036] The module for calculating the advancing speed of the adjacent water body is used to calculate the advancing speed of the adjacent water body of a single well according to the water invasion risk coefficient;

[0037] The prediction module is used to predict the future water breakthrough time of the gas well based on the well spacing between adjacent wells and the advancing speed of the adjacent water body using the constructed prediction model.

[0038] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the water invasion early warning method for fractured low-porosity sandstone gas reservoirs are implemented.

[0039] The present invention also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the water invasion early warning method for fractured low-porosity sandstone gas reservoirs are implemented.

[0040] Compared with the prior art, the present invention has the following beneficial technical effects:

[0041] The present invention provides a water invasion early warning method for fractured low-porosity sandstone gas reservoirs, which comprehensively considers the static geological factors and dynamic development factors of water invasion in deep / ultra-deep fractured low-porosity sandstone edge-water gas reservoirs, and realizes the quantitative evaluation of the risk of non-uniform water invasion in fractures and the accurate early warning of the time of water breakthrough in gas wells through the plane distribution chart of water invasion risk coefficient and the relationship chart between water invasion risk coefficient and the advancement speed of adjacent water bodies. The application results of a typical block example show that the production control plan is formulated in time by using water invasion risk evaluation and early warning technology, and the water breakthrough speed of gas reservoirs is effectively curbed after implementation. By curbing the water breakthrough speed of gas reservoirs, it is expected to increase the recovery rate of the block by 0.27%, and increase the economic benefits by 356 million yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a flow chart of a method for evaluating and early warning water invasion in fractured gas reservoirs according to an embodiment of the present invention;

[0043] Figure 2 This is a distribution chart of water intrusion risk coefficient of a single well in an actual block according to an embodiment of the present invention;

[0044] Figure 3 This is a top surface structural diagram of an actual block according to an embodiment of the present invention;

[0045] Figure 4 1 is a relationship diagram between the water invasion risk coefficient of a well and the advancing speed of an adjacent water body according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present invention more clear, the following is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, not all embodiments.

[0047] The components described and shown in the drawings and embodiments of the present invention may be arranged and designed in various configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0048] The present invention discloses a water intrusion early warning method for fractured low-porosity sandstone gas reservoirs, comprising the following process:

[0049] Obtain static geological parameters and dynamic parameters that affect water invasion in fractured gas reservoirs as evaluation indicators;

[0050] Determine the weight coefficient of each evaluation indicator;

[0051] The evaluation indexes of different gas wells are normalized to obtain the evaluation index parameters;

[0052] Based on the evaluation index parameters and the weight coefficient of each evaluation index, the water invasion risk coefficient of each single well in the block is calculated using the constructed mathematical model of water invasion risk coefficient and evaluation index;

[0053] Draw a water invasion risk plane distribution map based on the water invasion risk coefficient of each single well in the block, and judge the water invasion risk based on the water invasion risk coefficient plane distribution map and the actual gas well production situation;

[0054] Calculate the advancing speed of the adjacent water body according to the water invasion risk coefficient;

[0055] Based on the spacing between adjacent wells and the advancing speed of the adjacent water body, the constructed prediction model is used to predict the future water breakthrough time of the gas well.

[0056] The production conditions of the gas reservoir targeted by the present invention are as follows:

[0057] The gas reservoir is deeply buried (>4500m), with high temperature (formation temperature>100℃), ultra-high pressure (pressure coefficient>1.2), dense matrix (permeability<0.1mD), well-developed pore-fracture-fault multi-scale media, permeability difference of 5-6 orders of magnitude, and the presence of edge water.

[0058] Fractures are high-speed channels for water invasion. During the development of gas reservoirs, edge water invades non-uniformly along fractures and high-permeability strips, causing gas wells at the bottom of the structure to see water early. After seeing water, the production of the gas wells drops rapidly, and the wells may even be flooded and shut down. Fracture water invasion seriously affects the stable production and development effect of gas reservoirs.

[0059] The present invention provides a water intrusion early warning method for fractured low-porosity sandstone gas reservoirs, and the process steps are as follows:

[0060] ① The first step: Screen five evaluation indicators, including static geological parameters (gas well water avoidance height H, distance from gas well to edge water L, fracture mode F, reservoir permeability K) and dynamic parameters (gas production rate S) that affect water invasion in fractured gas reservoirs; Use the priority diagram method to quantitatively evaluate the indicators and determine the weights of the influence of gas well water avoidance height H, distance from gas well to edge water L, reservoir permeability K, fracture mode F, and gas production rate S on water invasion.

[0061] Differences from background technology:

[0062] The static geological parameters and dynamic parameters that cause water invasion are comprehensively considered. The overall effect of static geological parameters on gas well water invasion is that the closer the distance L between the gas well and the edge water, the smaller the water avoidance height H of the gas well, and the higher the reservoir permeability K, the more likely the gas well is to be invaded by water, that is, there is a positive correlation between reservoir permeability K and water invasion, and there is a negative correlation between the distance L between the gas well and the edge water and the water avoidance height H of the gas well and water invasion; the effect of dynamic parameters on gas well water invasion is that the greater the gas production rate S, the more likely the gas well is to be invaded by water, that is, there is a positive correlation between gas production rate S and water invasion.

[0063] The scientific principle of the priority diagram method: It is a mathematical and statistical analysis method that uses matrix diagrams to analyze the importance of various factors (conditions) to the goal (project success or failure, service quality) and provide a basis for management decisions. Let n be the number of comparison objects. The priority diagram is a chessboard diagram with n×n spaces. When making pairwise comparisons, 1.0, 0.5, and 0 can be selected to indicate the importance. "1" is used to indicate the relative "importance" in the pairwise comparison, and "0" is used to indicate the relative "unimportance". For the comparison with itself, "0.5" is assigned to the grids with the same serial number. The weight calculation method is to add the numbers filled in each grid in each row of the chessboard horizontally to obtain the single indicator score Aw, and then divide it by the total indicator score An to obtain the weight of each indicator.

[0064] The weight coefficient is determined according to the priority diagram method. Of course, there are also methods such as AHP method, factor analysis, entropy value method, etc. Each method has its own advantages and disadvantages and adaptability. In comparison, the priority diagram method is simple and practical, simple to calculate, and easier to understand.

[0065] ② The second step: Introduce comprehensive geological parameters (water intrusion risk coefficient), and establish the mathematical expression of the water intrusion risk coefficient and the five evaluation indicators based on the weights of the five indicators determined by the priority diagram method. The larger the value, the more likely the well area is to be water invaded, and vice versa, the more difficult it is for the well area to be water invaded.

[0066] Combining geological parameters - water intrusion risk coefficient (ω), the mathematical expression of water intrusion risk coefficient was finally established:

[0067] ω=(aK+bF+cS-dH-eL)×100%

[0068] Where: ω-water invasion risk coefficient, dimensionless; K-reservoir permeability, mD; H-gas well water avoidance height (i.e., the height difference between the bottom of the perforation section and the original gas-water interface) m; L-gas well to edge water distance, i.e., the plane distance between the gas well and the original gas-water interface m; S-gas production rate of the gas reservoir in that month; F-fracture mode, dimensionless; a, b, c, d, e-weight coefficients.

[0069] Differences from background technology:

[0070] For the first time, the mathematical expression of water intrusion risk coefficient and five evaluation indicators was established, realizing the quantitative evaluation of water intrusion risk.

[0071] Scientific principle:

[0072] The decisive factors for the speed of non-uniform water invasion in fractured edge-water gas reservoirs and the occurrence of water in gas wells are the geological factors of the gas reservoir itself (gas well water avoidance height, distance between gas well and edge-water, fracture mode, permeability) and the development system (gas production rate), which are the five evaluation indicators that affect water invasion. Geological factors are internal factors, development system is external factor, and fracture water invasion is the result of the combined effect of multiple factors.

[0073] ③The third step: normalize the five indicators of different gas wells, use the water invasion risk coefficient formula to calculate the water invasion risk coefficient of each single well in the block, and draw a plane distribution map of water invasion risk; use the single well spacing and water breakthrough time to calculate the advancement speed of the single well near the water body.

[0074] Differences from the background technology: According to the water invasion risk coefficient formula and the five evaluation indicators of gas wells, the quantitative calculation of water invasion risk coefficients of different gas wells is realized, so that the water invasion risk coefficients of gas wells on the plane can be obtained, and a plane distribution chart of water invasion risk coefficients can be drawn. The water invasion risk evaluation chart formed by the present invention can grasp the water invasion risk position of gas reservoirs, which has a certain guiding significance for water invasion prevention.

[0075] Scientific principle: Same as above.

[0076] ④ Step 4: Establish a relationship between the water intrusion risk coefficient and the advancing speed of the adjacent water body, form a chart, and use this relationship to adjust the gas production speed and control the water intrusion speed.

[0077] The calculation expression of the propulsion speed near the water body is:

[0078] Y=Aω(x) 2 -Bω(x)+C.

[0079] Y is the advancing speed of the adjacent water body, ω is the water intrusion risk coefficient, ω(x) represents the xth ω value, A, B, and C are coefficients, which are obtained based on the fitting of historical data.

[0080] Differences from background technology:

[0081] The correlation between the water invasion risk coefficient and the advancing speed of the adjacent water body can be obtained, and then the water breakthrough time of the gas well can be predicted according to the advancing speed of the adjacent water body and the well spacing of adjacent wells, so as to control the water invasion speed by adjusting the gas production speed, and by combining the actual block water invasion data with theoretical research, targeted measures to delay water invasion are proposed, providing technical support for water invasion early warning and development adjustment of fractured gas reservoirs.

[0082] Scientific principle:

[0083] The water invasion risk coefficient and the speed of the adjacent water body are the key parameters for water breakthrough in gas wells. The greater the water invasion risk coefficient, the more likely the well area is to experience water invasion. Combined with the speed of the adjacent water body, an accurate early warning of the time of water breakthrough in the gas well can be achieved.

[0084] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0085] A fractured gas reservoir has the characteristics of deep burial, high pressure, dense matrix, and developed fractures and edge water. The block began production in 2013 and completed the preparation of the preliminary development plan. In 2015, the annual gas production scale was built to 3.5 billion cubic meters, and 34 production wells were deployed. After 2016, water was seen in the gas wells in the lower part, and the production capacity dropped by more than 50%. The gas field has developed fractures and fractures as a whole, and the reservoir connectivity is good. By the end of 2017, 12 wells had seen water, and the water-gas ratio increased rapidly and had large differences (2-200m 3 / 10 4 m 3 ), the water invasion situation is severe, and the water breakthrough prediction of other wells has become a key issue facing gas reservoir development. Figure 1 As shown, the specific implementation of the water invasion early warning method for fractured gas reservoirs of the present invention includes:

[0086] Step S101, screening five evaluation indicators that affect water invasion: ① gas well water avoidance height (H); ② gas well to edge water distance (L); ③ reservoir permeability (K); ④ fracture mode (F); ⑤ gas production rate (S).

[0087] Step S102: The fracture mode of the block is a fracture network mode. The index weights are determined using the priority graph method and listed in a chessboard arrangement table (see Table 1). Then, the weight coefficients corresponding to the five evaluation indicators can be obtained.

[0088] Table 1. The chessboard arrangement table of indicator weights determined by the priority graph method

[0089]

[0090]

[0091] Step S103: Based on the weights of each indicator, establish a water intrusion risk coefficient formula:

[0092] ω=(0.04K+0.28F+0.36S-0.16H-0.16L)×100%.

[0093] Step S104: The five evaluation indicators of the 14 wells in the block are calculated according to the formula After normalization, the water invasion risk coefficient of each single well is calculated using the water invasion risk coefficient formula and listed in the data table (see Table 2).

[0094] Step S105: Figure 2 As shown, a water invasion risk coefficient chart of the block is drawn. The larger the water invasion risk coefficient, the more likely the well area is to be flooded. Conversely, the less likely the well area is to be flooded.

[0095] Step S106: The single well spacing can be obtained according to the well location coordinates. Figure 3 ) and water breakthrough time, calculate the advancing speed of a single well near the water body (see Table 3).

[0096] Step S107: Analyze and fit the relationship between the water intrusion risk coefficient and the advancing speed of the adjacent water body (see Table 4), and establish the relationship between the two parameters Y=11454ω(x): 2 - 470.42ω(x)+12.759(see Figure 4 ).

[0097] Step S108: predicting the water breakthrough time of the gas well by using the relationship between the water invasion risk coefficient and the advancing speed of the adjacent water body.

[0098] As shown in Table 2, taking Well A17 as an example, by substituting its relevant parameters, we get the water invasion coefficient ω=(0.04K+0.28F+0.36S-0.16H-0.16L)×100%=

[0099] (0.04*0.0714+0.28*0.203+0.36*0.106-0.16 *0.083-0.16*0.09)×100%=0.071, then substitute ω into the formula Y=11454ω(x) 2 -470.42ω(x) +12.759=25(m / day). As shown in Table 4, according to the water intrusion risk coefficient ω, the propulsion speed Y of the adjacent water body can be calculated.

[0100] The distance between Well A17 and the adjacent well A20 is 1380.58m, so it is expected that Well A17 will see water 1380.58 / 25=55 days after Well A20 sees water. The actual water-seeking time is shown in Table 3, which shows that Well A20 saw water on January 1, 2016, and Well A17 saw water on March 2, 2016, with a time interval of 61 days. The error is within 10%, and the prediction is relatively accurate.

[0101] Step S109, through calculation and analysis, the production of the block is controlled, from 4 million cubic meters / day to 2 million cubic meters / day, extending the water production time of the high-lying A14 well, A18 well, and the eastern A27 well, A28 well. By curbing the water breakthrough rate of the gas reservoir, it is expected that the cumulative gas production will increase by 422 million cubic meters, the recovery rate of the block will be increased by 0.27%, and the economic benefits will increase by 356 million yuan (see Table 5).

[0102] Table 2 Single well water invasion risk coefficient calculation table

[0103]

[0104] Table 3 Calculation table of propulsion speed near water body

[0105]

[0106]

[0107] Table 4 Correspondence between water intrusion risk coefficient ω and the advancing speed Y of the adjacent water body

[0108] ω Y 0.006 12 0.071 25 0.010 8 0.024 6 0.033 11 0.018 6 0.007 11 0.044 16

[0109] Table 5 Economic benefit evaluation table of curbing the increase of water breakthrough rate of gas reservoirs through block production control

[0110]

[0111] The present invention also discloses a fractured low-porosity sandstone gas reservoir water intrusion early warning system, comprising:

[0112] Parameter acquisition module, used to obtain static geological parameters and dynamic parameters affecting water invasion of fractured gas reservoirs as evaluation indicators;

[0113] A weight coefficient determination module is used to determine the weight coefficient of each evaluation index;

[0114] An evaluation index normalization module is used to normalize the evaluation indexes of different gas wells to obtain evaluation index parameters;

[0115] The water invasion risk coefficient calculation module is used to calculate the water invasion risk coefficient of each single well in the block based on the evaluation index parameters and the weight coefficient of each evaluation index, using the constructed mathematical model of water invasion risk coefficient and evaluation index;

[0116] The chart drawing module is used to draw the water invasion risk plane distribution chart according to the water invasion risk coefficient of each single well in the block, and judge the water invasion risk according to the water invasion risk plane distribution chart and the actual gas well production situation;

[0117] The module for calculating the advancing speed of the adjacent water body is used to calculate the advancing speed of the adjacent water body of a single well according to the water invasion risk coefficient;

[0118] The prediction module is used to predict the future water breakthrough time of the gas well based on the well spacing between adjacent wells and the advancing speed of the adjacent water body using the constructed prediction model.

[0119] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the water invasion early warning method for fractured low-porosity sandstone gas reservoirs are implemented. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc. The processor, the network interface, and the memory are interconnected through an internal bus, and the internal bus may be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the program may include a program code, and the program code includes computer operation instructions. The memory may include a memory and a non-volatile memory, and provide instructions and data to the processor.

[0120] The present invention also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the water invasion early warning method for fractured low-porosity sandstone gas reservoirs are implemented. Specifically, the computer-readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory may include a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include a read-only memory (ROM), a hard disk, a flash memory, an optical disk, a magnetic disk, etc.

[0121] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A water intrusion early warning method for fractured low-porosity sandstone gas reservoirs, characterized in that: The following processes are included: Obtain static geological parameters and dynamic parameters that affect water invasion in fractured gas reservoirs as evaluation indicators; Determine the weight coefficient of each evaluation indicator; Normalize the evaluation indicators of different gas wells to obtain evaluation indicator parameters; Based on the evaluation index parameters and the weight coefficient of each evaluation index, the water intrusion risk coefficient of each single well in the block is calculated using the constructed mathematical model of water intrusion risk coefficient and evaluation index; Draw a water invasion risk plane distribution map based on the water invasion risk coefficient of each single well in the block. Based on the water invasion risk coefficient plane distribution map and the actual gas well production situation, determine the water invasion risk; Calculate the advancing speed of the adjacent water body based on the water intrusion risk coefficient; Based on the spacing between adjacent wells and the advancing speed of the adjacent water body, the constructed prediction model is used to predict the future water breakthrough time of the gas well.

2. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 1, characterized in that: The static geological parameters include the gas well water avoidance height H, the distance between the gas well and the edge water L, the fracture mode F and the reservoir permeability K; Dynamic parameters include gas production rate S.

3. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 2, characterized in that: There is a positive correlation between reservoir permeability K and water invasion, a negative correlation between the distance L between the gas well and the edge water and the size of the gas well water avoidance height H and water invasion; there is a positive correlation between gas production rate S and water invasion.

4. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 2, characterized in that: The mathematical model of the water intrusion risk coefficient and evaluation index is: ω=(aK+bF+cS-dH-eL)×100%; Where ω is the water invasion risk coefficient; K is the reservoir permeability; H is the water avoidance height of the gas well; L is the distance between the gas well and the edge water; S is the gas production rate of the gas reservoir in that month; F is the fracture pattern; a, b, c, d, and e are the weight coefficients of the five evaluation indicators, respectively.

5. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 3, characterized in that: The weight coefficients of the evaluation indicators are determined using the priority diagram method.

6. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 1, characterized in that: The evaluation indicators of different gas wells are normalized, and the normalization formula is: L′ x is the normalized evaluation index, L x is the actual value of a certain evaluation index, x=1...........i, i is the number of evaluation indicators.

7. The water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to claim 1, characterized in that: The calculation expression of the propulsion speed near the water body is: Y=Aω(x) 2 -Bω(x)+C; Y is the advancing speed of the adjacent water body, ω is the water intrusion risk coefficient, ω(x) represents the x-th ω value; A, B, and C are coefficients obtained based on historical data fitting.

8. A water intrusion early warning system for fractured low-porosity sandstone gas reservoirs, characterized by: include: Parameter acquisition module, used to obtain static geological parameters and dynamic parameters that affect water invasion in fractured gas reservoirs as evaluation indicators; A weight coefficient determination module is used to determine the weight coefficient of each evaluation indicator; Evaluation index normalization module, used to normalize the evaluation indexes of different gas wells to obtain evaluation index parameters; The water intrusion risk coefficient calculation module is used to calculate the water intrusion risk coefficient of each single well in the block based on the evaluation index parameters and the weight coefficient of each evaluation index, using the established mathematical model of water intrusion risk coefficient and evaluation index; The chart drawing module is used to draw a water invasion risk plane distribution chart based on the water invasion risk coefficient of each single well in the block. Based on the water invasion risk plane distribution chart and the actual gas well production situation, the water invasion risk is judged; The module for calculating the speed of the water body near the well is used to calculate the speed of the water body near the well based on the water invasion risk coefficient; The prediction module is used to predict the future water breakthrough time of the gas well based on the well spacing between adjacent wells and the propulsion speed of the adjacent water body using the constructed prediction model.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the water intrusion early warning method for fractured low-porosity sandstone gas reservoirs as claimed in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the water intrusion early warning method for fractured low-porosity sandstone gas reservoirs according to any one of claims 1 to 7 are implemented.

Images