Ultra-low permeability reservoir well testing dynamic early warning method based on water injection well and related device

Abstract

The invention discloses an ultra-low permeability reservoir well test dynamic early warning method based on a water injection well and a related device. The method comprises the following steps: acquiring pressure drop speed data of the water injection well; detecting the ultra-low permeability reservoir water drive radius and judging stratum seepage characteristics and reservoir dominant channels by utilizing the obtained water injection well pressure drop speed data and well testing software; and presetting an oil production well exploitation safety standard, and based on the model change in the well testing software, pre-warning whether the stratum flow conductivity meets the oil production well exploitation safety standard or not. The water injection strategy and parameters can be adjusted in time by monitoring the pressure drop speed of the water injection well in real time and analyzing the water drive radius and the stratum seepage characteristics in combination with well testing software; secondly, the mining safety standard of the oil production well is preset, and based on the early warning function of well testing software, potential safety hazards such as insufficient stratum flow conductivity can be found in time.

Description

Technical Field

[0001] This invention belongs to the field of well testing technology for ultra-low permeability reservoirs, specifically relating to a dynamic early warning method and related device for well testing of ultra-low permeability reservoirs based on water injection wells. Background Technology

[0002] Ultra-low permeability reservoirs have poor physical properties. Conventional dynamic monitoring data, acquired and applied according to conventional reservoir models, suffer from poor data matching and cannot accurately reflect the reservoir's waterflooding status. Current research on waterflooding monitoring mainly employs two methods: tracers and the waterflood front. While the waterflood front is a novel monitoring technology, its reliability remains to be verified, and it generally requires the use of tracers for validation. Water well pressure drawdown testing technology is relatively mature, providing high-quality data with interpretation charts and methods closely aligned with production dynamics. However, it fails to accurately characterize the waterflooding impact and energy transmission range, and its data application rate is low. It is frequently used in conjunction with pulse testing and tracers for analyzing waterflooding conditions in well groups, and has not yet become a routine application to guide well group adjustments and improvements in development outcomes.

[0003] In China, the acquisition and analysis of dynamic monitoring data are mainly based on the acquisition and application of dynamic monitoring data for conventional oil reservoirs. In particular, pressure well testing and profile monitoring, which can be used to characterize water drive, are mainly based on medium and high permeability sandstone and conglomerate reservoirs. Although relevant regulations have been made for low-permeability and ultra-low-permeability reservoirs, no in-depth research or deployment experiments have been carried out on ultra-low-permeability reservoirs. As a result, dynamic monitoring of conventional oil reservoirs cannot provide accurate early warning for well testing in ultra-low-permeability reservoirs. Summary of the Invention

[0004] This invention provides a dynamic early warning method and related device for well testing in ultra-low permeability reservoirs based on water injection wells, which solves the technical defects in the prior art, where the lack of in-depth research and deployment experiments on ultra-low permeability reservoirs has resulted in the inability of dynamic monitoring of conventional reservoirs to provide accurate early warning for well testing in ultra-low permeability reservoirs.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] Firstly, a dynamic early warning method for well testing in ultra-low permeability reservoirs based on water injection wells is provided, including:

[0007] Obtain data on the rate of pressure drop in injection wells;

[0008] Using the obtained data on the rate of pressure drop in the injection wells, and through well testing software, the water drive radius of ultra-low permeability reservoirs is detected, and formation seepage characteristics and reservoir dominant channels are determined.

[0009] The system presets safety standards for oil well production and, based on model changes in the well testing software, provides early warnings about whether the formation conductivity meets the safety standards for oil well production.

[0010] Furthermore, data on the rate of pressure drop in injection wells is obtained, specifically including:

[0011] A pressure gauge is used to measure the rate of pressure drop in the injection well, and the data is transmitted to the well testing software.

[0012] Furthermore, using the acquired data on the rate of pressure drop in the injection wells, and through well testing software, the water drive radius of ultra-low permeability reservoirs is detected to determine formation seepage characteristics and dominant reservoir channels, specifically including:

[0013] Using the acquired data on the rate of pressure drop in the injection well, and through well testing software, it is determined whether the formation is a homogeneous formation or a fractured formation. When the formation is determined to be a homogeneous formation, a homogeneous reservoir model is used to display the water drive wave range and fracture length. When the formation is determined to be a fractured formation, a finite-conductivity fracture model or a wireless-conductivity fracture model is used to display the water drive wave range and fracture length.

[0014] The pressure change data of the same injection well over one year is obtained, and the curve changes are displayed using well testing software. Based on the curve changes, the formation seepage characteristics are determined.

[0015] The well testing software calculates the length of fractures in ultra-low permeability reservoirs using data on the rate of pressure drop in water injection wells. Based on the fracture length, it matches the corresponding model and displays the results visually, then determines the reservoir channel conditions based on the displayed data.

[0016] Furthermore, when the curve changes from low to high, the formation gradually shows improvement; when the curve changes from high to low, the formation develops from large pores to fractures.

[0017] Furthermore, when the crack length is long, an infinite-conduction crack model is matched; when the crack length is short, a finite-conduction crack model is matched.

[0018] When the crack length is long, the channel is well developed; when the crack length is short, the channel is poorly developed.

[0019] Furthermore, a pre-defined safety standard for oil well production is established. Based on model changes in the well testing software, it is determined whether the formation conductivity meets the safety standard for oil well production. Specifically, this includes:

[0020] The safety standard for oil well production is that the pressure drop of ultra-low permeability Class I reservoirs should not exceed 3-6 MPa, ultra-low permeability Class II reservoirs should not exceed 2-4 MPa, and ultra-low permeability Class III reservoirs should not exceed 1-3 MPa. When the water drive wave range is not greater than 150 m and the annual test pressure drop is greater than 3 MPa, an early warning will be issued.

[0021] When the curve characteristics show linear flow, early warning and remediation are needed; when the fracture change is greater than 25m, the dominant channels of the reservoir should be treated in a timely manner.

[0022] When the model is changed from a homogeneous reservoir model to a finite or infinitely conductive fracture model, it is necessary to provide timely warning of the formation of unidirectional seepage channels.

[0023] Secondly, a well test method for ultra-low permeability reservoirs is provided, which uses the aforementioned early warning method for dynamic early warning.

[0024] Thirdly, a dynamic early warning system for well testing in ultra-low permeability reservoirs based on water injection wells is provided, including:

[0025] The data acquisition module is used to acquire data on the rate of pressure drop in water injection wells;

[0026] The detection module is used to detect the water drive radius of ultra-low permeability reservoirs;

[0027] The judgment module is used to determine the formation seepage characteristics and the dominant channels in the reservoir;

[0028] The early warning module is used to provide early warnings on whether the formation's diversion capacity meets the safety standards for oil well production.

[0029] Fourthly, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable in the processor, wherein the processor executes the computer program to implement the steps of the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described above.

[0030] Fifthly, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, implements the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described above.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. By monitoring the pressure drop rate of injection wells in real time and analyzing the water drive radius and formation seepage characteristics using well testing software, water injection strategies and parameters can be adjusted in a timely manner to improve water injection development effectiveness and enable fuller utilization of the reservoir. 2. By setting pre-defined safety standards for production wells and leveraging the early warning function of well testing software, potential safety hazards such as insufficient formation conductivity can be detected promptly, allowing for corresponding preventative and remedial measures to reduce production risks. 3. Finally, through refined dynamic early warning and management of ultra-low permeability reservoirs, the fluid distribution and flow patterns within the reservoir can be understood more accurately, leading to the development of more rational production plans and improved resource utilization efficiency.

[0033] 2. Using professional pressure gauges ensures the accuracy and reliability of data on the rate of pressure drop in injection wells. Real-time monitoring of pressure changes in injection wells via pressure gauges allows for the timely detection of pressure drop trends and rates, providing timely data support for dynamic early warning. This real-time monitoring capability facilitates rapid response to reservoir dynamics and allows for appropriate adjustments. The measured data is automatically transmitted to the well testing software, reducing manual intervention and data entry steps, thus improving work efficiency and automation. This not only reduces the risk of human error but also makes the data analysis process more efficient and convenient. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This invention provides a flowchart of a dynamic early warning and discrimination method for well testing in ultra-low permeability reservoirs based on water injection wells;

[0036] Figure 2 A schematic diagram of a homogeneous reservoir test model in a dynamic early warning method for ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0037] Figure 3 A schematic diagram of an infinite seepage model in a homogeneous reservoir model for a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention.

[0038] Figure 4 This is a schematic diagram of an infinitely large homogeneous reservoir model in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by the present invention.

[0039] Figure 5A schematic diagram of the physical model of an infinitely conductive vertical fractured well in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by the present invention.

[0040] Figure 6 A schematic diagram of an infinitely conductive vertical fracture seepage model in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0041] Figure 7 A schematic diagram of the theoretical plate of the infinitely conductive vertical fracture in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by the present invention;

[0042] Figure 8 A schematic diagram of the reservoir impact of an infinitely conductive vertical fracture model well in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention.

[0043] Figure 9 A schematic diagram of the skin effect of an infinitely conductive vertical fracture model in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells, provided by this invention.

[0044] Figure 10 The pressure test data of Zhongjiang 294-8 is shown in the figure. This invention provides a dynamic early warning method for ultra-low permeability reservoirs based on water injection wells.

[0045] Figure 11 The pressure double logarithmic curve of Zhongjiang 294-8 is provided by the present invention for a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells;

[0046] Figure 12 The double logarithmic pressure curve of the ring 202-97 is provided in the present invention as a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells.

[0047] Figure 13 The pressure test data diagram of the ring 202-97 in the dynamic early warning method for ultra-low permeability reservoirs based on water injection wells provided by the present invention;

[0048] Figure 14 The pressure double logarithmic curve in 2020 in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by the present invention;

[0049] Figure 15 The pressure double logarithmic curve for 2021 in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0050] Figure 16 The pressure double logarithmic curve for 2022 in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0051] Figure 17 The water intake profile of Zhonghong 15-03 is provided in the present invention as a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells.

[0052] Figure 18 The corresponding effective oil well production curve in the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0053] Figure 19 The pressure double logarithmic curve in 2019 in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by the present invention;

[0054] Figure 20 The pressure double logarithmic curve for 2022 in a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0055] Figure 21 The present invention provides a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells, using the water absorption profile of Zhongjiang 81-49.

[0056] Figure 22 The current production status map of the Zhongjiang 81-49 well group is provided by the present invention for a dynamic early warning method for ultra-low permeability reservoirs based on water injection wells.

[0057] Figure 23 The 2018 double logarithmic curve in the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0058] Figure 24 The 2019 double logarithmic curve in the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells provided by this invention;

[0059] Figure 25 The production curve of the Luo 262-247 well group is provided in the present invention as a dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells.

[0060] Figure 26 The present invention provides a schematic diagram of a dynamic early warning system for well testing in ultra-low permeability reservoirs based on water injection wells. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0062] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0063] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0064] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0066] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0067] Ultra-low permeability reservoirs have poor physical properties. Conventional dynamic monitoring data, acquired and applied according to conventional reservoir models, suffer from poor data matching and cannot accurately reflect the reservoir's waterflooding status. Current research on waterflooding monitoring mainly employs two methods: tracers and the waterflood front. While the waterflood front is a novel monitoring technology, its reliability remains to be verified, and it generally requires the use of tracers for validation. Water well pressure drawdown testing technology is relatively mature, providing high-quality data with interpretation charts and methods closely aligned with production dynamics. However, it fails to accurately characterize the waterflooding impact and energy transmission range, and its data application rate is low. It is frequently used in conjunction with pulse testing and tracers for analyzing waterflooding conditions in well groups, and has not yet become a routine application to guide well group adjustments and improvements in development outcomes.

[0068] In China, the acquisition and analysis of dynamic monitoring data are mainly based on the acquisition and application of dynamic monitoring data for conventional oil reservoirs. In particular, pressure well testing and profile monitoring, which can be used to characterize water drive, are mainly based on medium and high permeability sandstone and conglomerate reservoirs. Although relevant regulations have been made for low-permeability and ultra-low-permeability reservoirs, no in-depth research or deployment experiments have been carried out on ultra-low-permeability reservoirs. As a result, dynamic monitoring of conventional oil reservoirs cannot provide accurate early warning for well testing in ultra-low-permeability reservoirs.

[0069] To address the aforementioned technical deficiencies, the inventors have provided a dynamic early warning method and related device for well testing in ultra-low permeability reservoirs based on water injection wells.

[0070] In a first aspect, embodiments of the present invention provide a dynamic early warning method for well testing in ultra-low permeability reservoirs based on water injection wells, such as... Figures 1-25 As shown, it includes:

[0071] S101. Obtain data on the rate of pressure drop in the injection well; for example, such as... Figure 2 The diagram shown is a schematic of a homogeneous reservoir well test model. Depending on specific operational requirements, a cycle of 15, 18, or 20 days is used. Pressure drop rate data from the injection well is measured using a pressure gauge, and the data is transmitted to the well test software. Figure 10 and Figure 11 As shown, the Luo 228 Chang 8 reservoir has poor reservoir properties and belongs to the ultra-low permeability type 2. The normal pressure variation range is 3-4 MPa. Figure 10 In the middle section, the test pressure of the Jiang 294-8 water injection well dropped from 48.54 MPa to 32.77 MPa, indicating a rapid pressure drop in the well. Figure 11 In the middle, the double logarithmic curve showed a 1 / 2 linear flow, indicating well-developed near-well fractures and strong water absorption capacity. After water shut-off and profile control in 2021, periodic water injection was implemented to ensure its effectiveness. The water cut of the corresponding oil well Jiang 294-7 decreased from 80% to about 50%, and the water control and oil stabilization were good.

[0072] S102. Using the obtained water injection well pressure drop rate data and well testing software, the water drive radius of the ultra-low permeability reservoir is detected to determine the formation seepage characteristics and the dominant reservoir channels. For example, using the obtained water injection well pressure drop rate data and well testing software, the water flow radius is automatically calculated and displayed as a curve. The formation is manually judged as a homogeneous or fractured formation based on the curve. The conditions for judging a homogeneous formation are: first, the pressure of the water fluid in a single water flow channel is compressible, and the reservoir seepage satisfies Darcy's law; second, the reservoir is horizontally uniform in thickness and isotropic, with good interlayers between the upper and lower layers, and the formation pressure distribution is uniform under original conditions; third, the influence of the reservoir's own gravity and capillary force is ignored; fourth, the temperature is consistent during the water flow process; and fifth, wellbore storage and skin effect are considered.

[0073] Based on these five conditions, the mathematical model algorithm formula for homogeneous oil reservoirs is derived as follows:

[0074]

[0075] Where: r is the radius, K is the permeability, P is the pressure, T is the time, C is the compressibility factor, and u is the viscosity.

[0076] The criteria for determining a fractured formation are as follows: It is assumed that only one fracture is forced open, this fracture penetrates the entire oil layer, is symmetrical with the wellbore, and has a half-length of Xf; the fracture has infinite conductivity, there is no pressure drop along the fracture direction, and the fracture width is zero. Other assumptions include: first, the fluid is single-phase and slightly compressible; second, gravity and capillary forces are ignored; third, the formation fluid is a slightly compressible single-phase fluid; and fourth, the fluid flow satisfies linear Darcy flow. When the formation is determined to be homogeneous, a homogeneous reservoir model is used to display the water-drive wave range and fracture length. The homogeneous reservoir model includes a homogeneous reservoir physical model, a homogeneous reservoir mathematical model, a homogeneous reservoir flow law model, a homogeneous reservoir model graphical model, a basic model, an inner boundary module, and an outer boundary module. The homogeneous reservoir mathematical model is used to establish numerical formulas, the homogeneous reservoir flow law model is used to summarize the laws, and the homogeneous reservoir model graphical model is used to display the data graphically. Figure 4 and Figure 7 In the medium-quality oil reservoir model diagram, Stage I is the pure well reservoir section, where the pressure and pressure conductivity curves coincide and form a straight line with a slope of 1; Stage II is the transition section between the wellbore and the formation; Stage III is the radial flow response section, where the pressure conductivity curve forms a horizontal line with a slope of 0.5.

[0077] When the formation is determined to be a fractured formation, a finite-conductivity fracture model or an infinite-conductivity fracture model is used to display the water-drive wave range and fracture length. The infinite-conductivity fracture model includes an infinite-conductivity fracture physical model, an infinite-conductivity fracture digital model, infinite-conductivity fracture seepage laws, and an infinite-conductivity fracture model chart. The pressure response of a vertical well in an infinite-conductivity fracture digital model with a sealed top and bottom, laterally infinite oil and gas reservoir, fully fractured, and with uniform flow is as follows:

[0078]

[0079] Where D is the pressure in the vertical well, and z is the Laplace variable. In actual calculations, xfD = 0.732 can be taken as the equivalent pressure point.

[0080]

[0081] The above equation is the bottomhole pressure response solution considering the skin and well reservoir.

[0082] In the infinite-conductivity fracture model diagram, Stage I represents the pure well reservoir section, where the pressure and permeability curves coincide as a straight line with a slope of 1; Stage II is the transition section between the wellbore and the fracture; Stage III is the linear flow section of the fracture, where the permeability curve is a horizontal line with a slope of 0.5; Stage IV is the transition section between the fracture and the formation; and Stage V is the radial flow section of the formation, where the permeability curve is a horizontal line. The influence of the well reservoir on the diagram is mainly reflected in the upper and lower positions of the leading edge of the permeability curve on the logarithmic diagram. The larger the well reservoir, the lower the position of the pressure and permeability curve segment. The skin factor mainly affects the height of the hump in the middle of the permeability curve on the logarithmic diagram. The larger the skin factor, the more obvious and higher the hump of the permeability curve. Figure 7 As shown.

[0083] like Figure 2 and Figure 3 As shown; a smaller crack data value indicates a shorter crack length and a smaller water-driven wave range; a larger crack data value indicates a longer crack length and a larger water-driven wave range. Figure 12 and Figure 13 As shown, the double logarithmic curve of well Huan 202-97 indicates a large water drive sweep area of ​​217m. Given that the well spacing in this reservoir is only 250m, the risk of water breakthrough in the corresponding wells is high. The water injection rate was optimized and lowered. The well group's production capacity and water cut remained relatively stable, with a stable production period of 7 months. Then, by acquiring one year's pressure change data from the same injection well and using well testing software to display the curve changes, the formation seepage characteristics were manually determined based on the curve change amplitude and data range. This process does not require a model. Specifically, when the displayed curve change increases from low to high, the formation gradually shows improvement; when the displayed curve change decreases from high to low, the formation develops from large porosity to fractures. For example... Figures 14-18As shown, the Hong 15-03 well exhibited uneven vertical water absorption, leading to the formation of a dominant channel. In 2021, the pressure tested was significantly lower than in 2020, decreasing from 17.1 MPa to 9.3 MPa, indicating water breakthrough. Through fine-tuning of the upper layers, the water injection rate in the upper layer of the Hong 15-03 well was controlled, decreasing from 10 m³ to 5 m³, while the lower layer injection rate increased from 5 m³ to 8 m³. After these adjustments, the water well pressure tested again in 2022 increased from 9.3 MPa to 13.5 MPa, demonstrating good water control and oil stabilization effects.

[0084] Secondly, the well testing software calculates the fracture length in ultra-low permeability reservoirs using data on the pressure drop rate of injection wells, and matches the corresponding model based on the fracture length, displaying the results visually. Figures 5-9 As shown, the reservoir channel condition is determined based on the displayed image. Specifically, when the fracture length is long, an infinite-conductivity fracture model is used; when the fracture length is short, a finite-conductivity fracture model is used. Longer fracture lengths indicate well-developed channels, while shorter fracture lengths indicate poorly developed channels.

[0085] like Figures 19-22 As shown, taking well Jiang 81-49 as an example, Figure 19 In May 2019, the water injection well was shut down and the well test interpretation showed that the relative permeability of the water phase in the inner zone (water zone) was 0.39 kJ / mD, and the fracture half-length was 38.3 m. Figure 20 The relative permeability of the water phase in the inner zone, as interpreted by the well shutdown test in May 2022, was 0.13 kJ / mD, and the fracture half-length was 63 m. The pressure differential and pressure derivative curves in the logarithmic coordinate system of this well exhibit typical linear flow characteristics, i.e., fracture seepage characteristics. This is mainly because the dominant flow channels develop more extensively with the continuation of the injection time. The fracture half-length increased during the well shutdown test in May 2022 (from 38.3 m to 63 m), which can be considered as an increase of 24.7 m in the dominant flow channels during the two well shutdowns. Figure 22 In the process, refined injection is implemented to improve the reservoir's advantageous channels and enhance water drive efficiency.

[0086] S103. Preset safety standards for oil well production. Based on model changes in the well testing software, issue early warnings regarding whether the formation conductivity meets the safety standards for oil well production. For example, the preset safety standards for oil well production are: pressure drop of no more than 3-6 MPa for ultra-low permeability Class I reservoirs, no more than 2-4 MPa for ultra-low permeability Class II reservoirs, and no more than 1-3 MPa for ultra-low permeability Class III reservoirs. An early warning is issued when the water drive wave range is no more than 150 m and the annual test pressure drop is greater than 3 MPa; when the curve characteristics are linear flow, early warning and remediation are initiated; when fracture changes are greater than 25 m, the dominant channels in the reservoir should be addressed promptly; when the model changes from a homogeneous reservoir model to a finite or infinite conductivity fracture model, an early warning should be issued regarding the formation of unidirectional seepage channels. Figures 23-25As shown, taking well Hu 262-247 in Luo 247 area as an example, the model interpreted by the two-year comparative well test has changed, from... Figure 23 The homogeneous reservoir model in the middle became Figure 24 The finite-conductivity fracture model indicates that the reservoir in ultra-low permeability oil well testing has changed from homogeneous flow to fractured flow, forming unidirectional flow channels. This necessitates timely early warning and adjustment of water injection policies, such as... Figure 25 As shown, the water injection volume was controlled, and the effect after adjustment was obvious. The corresponding well group showed an increase in liquid volume and a decrease in water cut.

[0087] Secondly, embodiments of the present invention provide a well test for an ultra-low permeability reservoir, which uses the aforementioned early warning method for dynamic early warning.

[0088] Thirdly, embodiments of the present invention provide a dynamic early warning system for well testing in ultra-low permeability reservoirs based on water injection wells, such as... Figure 26 As shown, it includes:

[0089] The data acquisition module is used to acquire data on the rate of pressure drop in water injection wells;

[0090] The detection module is used to detect the water drive radius of ultra-low permeability reservoirs;

[0091] The judgment module is used to determine the formation seepage characteristics and the dominant channels in the reservoir;

[0092] The early warning module is used to provide early warnings on whether the formation's diversion capacity meets the safety standards for oil well production.

[0093] Fourthly, embodiments of the present invention provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable in the processor. When the processor executes the computer program, it implements the steps of the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described above.

[0094] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described above.

[0095] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

[0096] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0097] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0098] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0099] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamic early warning method for well testing in ultra-low permeability reservoirs based on water injection wells, characterized in that, include: Obtain data on the rate of pressure drop in injection wells; Using the obtained data on the rate of pressure drop in the injection wells, and through well testing software, the water drive radius of ultra-low permeability reservoirs is detected, and formation seepage characteristics and reservoir dominant channels are determined. The system presets safety standards for oil well production and, based on model changes in the well testing software, provides early warnings about whether the formation conductivity meets the safety standards for oil well production.

2. The method according to claim 1, characterized in that, Obtain data on the rate of pressure drop in injection wells, specifically including: A pressure gauge is used to measure the rate of pressure drop in the injection well, and the data is transmitted to the well testing software.

3. The method according to claim 1, characterized in that, Using the acquired data on the rate of pressure drop in the injection wells, and through well testing software, the water drive radius of ultra-low permeability reservoirs is detected to determine formation seepage characteristics and dominant reservoir channels, specifically including: Using the acquired data on the rate of pressure drop in the injection well, and through well testing software, it is determined whether the formation is a homogeneous formation or a fractured formation. When the formation is determined to be a homogeneous formation, a homogeneous reservoir model is used to display the water drive wave range and fracture length. When the formation is determined to be a fractured formation, a finite-conductivity fracture model or a wireless-conductivity fracture model is used to display the water drive wave range and fracture length. The pressure change data of the same injection well over one year is obtained, and the curve changes are displayed using well testing software. Based on the curve changes, the formation seepage characteristics are determined. The well testing software calculates the length of fractures in ultra-low permeability reservoirs using data on the rate of pressure drop in water injection wells. Based on the fracture length, it matches the corresponding model and displays the results visually, then determines the reservoir channel conditions based on the displayed data.

4. The method according to claim 3, characterized in that, When the curve changes from low to high, the formation gradually shows improvement; when the curve changes from high to low, the formation develops from large pores to fractures.

5. The method according to claim 3, characterized in that, When the crack length is long, we match the infinite flow crack model; when the crack length is short, we match the finite flow crack model. When the crack length is long, the channel is well developed; when the crack length is short, the channel is poorly developed.

6. The method according to claim 1, characterized in that, The system presets safety standards for oil well production and, based on model changes in the well testing software, provides early warnings regarding whether the formation conductivity meets these standards. Specifically, this includes: The safety standard for oil well production is that the pressure drop of ultra-low permeability Class I reservoirs should not exceed 3-6 MPa, ultra-low permeability Class II reservoirs should not exceed 2-4 MPa, and ultra-low permeability Class III reservoirs should not exceed 1-3 MPa. When the water drive wave range is not greater than 150 m and the annual test pressure drop is greater than 3 MPa, an early warning will be issued. When the curve characteristics show linear flow, early warning and remediation are needed; when the fracture change is greater than 25m, the dominant channels of the reservoir should be treated in a timely manner. When the model is changed from a homogeneous reservoir model to a finite or infinitely conductive fracture model, it is necessary to provide timely warning of the formation of unidirectional seepage channels.

7. A well test method for ultra-low permeability reservoirs, characterized in that, The well test employs the dynamic early warning method for ultra-low permeability reservoir well testing based on water injection wells as described in any one of claims 1-6.

8. A dynamic early warning system for well testing in ultra-low permeability reservoirs based on water injection wells, characterized in that, include: The data acquisition module is used to acquire data on the rate of pressure drop in water injection wells; The detection module is used to detect the water drive radius of ultra-low permeability reservoirs; The judgment module is used to determine the formation seepage characteristics and the dominant channels in the reservoir; The early warning module is used to provide early warnings on whether the formation's diversion capacity meets the safety standards for oil well production.

9. An electronic device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable in the processor. When the processor executes the computer program, it implements the steps of the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described in any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the dynamic early warning method for well testing of ultra-low permeability reservoirs based on water injection wells as described in any one of claims 1 to 6.

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