Vertical well lateral broadband fracturing test method and device, and related model making method

Abstract

The present invention discloses a vertical well lateral broadband fracturing test method and device, and a related model making method. The testing method comprises: using a core plate to make a vertical well network model; vacuuming the vertical well network model and injecting formation water to a saturated state; injecting crude oil into the vertical well network model according to a row injection and production method; injecting crude oil into the vertical well network model according to a cross injection and production method until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing test model that can simulate the formation conditions of the oil reservoir to be tested. An oil displacement experiment is conducted on a conventional fracturing model and a broadband fracturing model, and the pressure sweep range, oil displacement efficiency, and oil saturation of the two models are compared to determine whether the oil reservoir to be tested is suitable for broadband fracturing. It can simulate a more realistic field environment, and can draw conclusions from multiple angles on whether broadband fracturing is suitable, thereby improving the reliability, accuracy, and applicability of the vertical well lateral broadband fracturing test.

Description

Technical Field

[0001] The present invention relates to the field of vertical well lateral broadband fracturing testing, and in particular to a vertical well lateral broadband fracturing testing method and device, and a related model manufacturing method. Background Art

[0002] Low / ultra-low permeability reservoirs are characterized by poor physical properties, complex microstructures, fine pore throats, low permeability, and strong heterogeneity. These reservoirs exhibit rapid natural production decline and low yields, making conventional development methods difficult to achieve economic production capacity. Therefore, fracturing stimulation is generally required for production enhancement. As reservoir properties deteriorate, conventional fracturing in older vertical wells in oilfields makes it difficult to develop complex fracture networks. Consequently, a large amount of residual oil is distributed on both sides of the artificial fractures, resulting in low oil production increases, rapid decline, low single-well production, a short effective life, and low ultimate recovery, all leading to insignificant production enhancement. Conventional refracturing cannot meet the production needs of these reservoirs. Therefore, wide-band fracturing can be considered for these reservoirs. Currently, wide-band fracturing trials have been conducted in some oilfields to address the difficulty in utilizing lateral residual oil in older vertical wells. While successful trials have shown that increasing the appropriate width can increase the drainage area and boost cumulative production, not all wide-band fracturing trials are successful. Clearly, the implementation of wide-band fracturing requires the reservoir to meet certain applicable conditions, such as permeability that meets certain requirements for wide-band fracturing. Therefore, testing whether the reservoir is suitable for wide-width fracturing is a technical issue that must be resolved before implementing wide-width fracturing. Summary of the Invention

[0003] While researching reservoir conditions suitable for wide-band fracturing, the inventors discovered that existing methods lacked a physical simulation method for the flow patterns of vertical wide-band lateral fracturing in low- and ultra-low-permeability reservoirs. Consequently, it was impossible to determine the flow patterns and applicability of wide-band lateral fracturing through physical simulation experiments. Being able to preemptively determine reservoir suitability for wide-band fracturing through indoor physical simulation experiments would greatly facilitate the real-time application of wide-band fracturing technology.

[0004] Currently, the most common physical simulation experiments conducted are one-dimensional. However, one-dimensional models can only simulate the linear flow of fluids in porous media, but cannot account for changes in fractures, well patterns, and injection-production methods. This is inconsistent with actual oilfield development and cannot simulate the suitability of oil wells for broadband fracturing. Simulation experiments using two-dimensional or three-dimensional models often employ artificially encapsulated sandfill models. In recent years, outcrop models and large-scale physical simulation experimental systems have been used to study the seepage patterns of different injection media, such as vertical and horizontal wells, in low-permeability, ultra-low-permeability, and tight reservoir conditions. However, research on the seepage patterns of different injection media, such as vertical and horizontal wells, has been limited to conventional fracturing conditions, and physical simulation experimental methods for broadband fracturing in vertical wells have not been explored.

[0005] In order to at least partially solve the technical problems existing in the prior art, the inventors have made the present invention, and through specific implementation methods, provide a vertical well lateral broadband fracturing testing method and device, and a related model making method.

[0006] In a first aspect, an embodiment of the present invention provides a method for preparing a vertical well volume fracturing experimental model, comprising:

[0007] A vertical well pattern model is produced using a core plate; the vertical well pattern model includes fractures and multiple injection and production holes arranged according to the well pattern form, volume fracturing type and parameters of the oil reservoir to be tested, as well as pressure measurement points and / or resistivity measurement points, wherein the multiple injection and production holes include at least one injection hole for oil displacement test and at least one oil displacement test production hole;

[0008] The vertical well pattern model is vacuumed, and at least one injection and production hole is selected as a saturated water hole to inject formation water into the model until it reaches a saturated state;

[0009] Injecting crude oil into the vertical well pattern model in a row-shaped injection and production pattern, with one row of injection and production holes serving as saturated oil injection holes and the other row of injection and production holes serving as saturated oil production holes, until the saturated oil production holes start to discharge only oil instead of water;

[0010] Crude oil is injected into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are arranged alternately and at intervals until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model that can simulate the formation conditions of the oil reservoir to be tested.

[0011] In some optional embodiments, the method of using a core plate to make a vertical well pattern model includes:

[0012] Determine the type and parameters of the fractures to be arranged according to the volume fracturing type and parameters of the reservoir to be tested, and arrange the fractures on the core plate; the volume fracturing type includes conventional fracturing and broadband fracturing; the fracture type includes conventional fracturing fractures and broadband fracturing fractures;

[0013] Determine the locations of injection and production holes according to the well pattern of the reservoir to be measured and the locations of the selected pressure measurement points, and then arrange the injection and production holes; wherein the injection and production holes arranged at the pressure measurement points are shallow holes, and the injection and production holes at other locations are deep holes;

[0014] Arranging a pressure measuring device at a pressure measuring point and / or arranging a resistivity measuring device at a resistivity measuring point, installing an injection-production well joint for the injection-production hole, and filling the fracture;

[0015] The core plate is sealed to obtain a vertical well pattern model.

[0016] In some optional embodiments, determining the type and parameters of fractures to be arranged based on the volume fracturing type and parameters of the reservoir to be tested, and arranging fractures on the core plate includes:

[0017] According to the volume fracturing type and the number, length and width of the fractures in the reservoir to be tested, the type, number, length and width of the fractures to be arranged are determined according to the scaling rules, and the fractures are arranged on the core plate.

[0018] In some optional embodiments, determining the locations of injection and production holes to be arranged and arranging the injection and production holes according to the well pattern of the oil reservoir to be measured and the locations of the selected pressure measurement points includes:

[0019] According to the well pattern of the reservoir to be tested, deep holes are drilled in the designated corners and the middle of the cracks of the core plate, and shallow holes are drilled at the pressure measurement points;

[0020] The deep holes and shallow holes are cleaned and dried to obtain arranged injection and production holes.

[0021] In some optional embodiments, the vertical well pattern model is vacuumed, and at least one injection and production hole is selected as a saturated water hole to inject formation water into the model to a saturated state, comprising:

[0022] Detecting the connectivity of each injection and production hole in the vertical well pattern model;

[0023] If the connectivity is normal, at least one injection and production hole is reserved as a saturated water hole, at least one injection and production hole is used as a vacuum monitoring point, and the other injection and production holes are used as vacuum points. The vertical well pattern model is vacuumed through the vacuum points. When it is determined that the vacuum degree meets the requirement based on the detection results of the vacuum monitoring points, formation water is injected into the model through the saturated water hole, and the formation water is absorbed by the vertical well pattern model until it reaches a saturated state.

[0024] In some optional embodiments, crude oil is injected into the vertical well pattern model in a row-by-row injection-production manner, wherein one row of injection-production holes serves as saturated oil injection holes and another row of injection-production holes serves as saturated oil production holes, until the saturated oil production holes change from discharging water to discharging only oil, including:

[0025] The Nth row of injection and production holes in the vertical well pattern model is connected to a displacement pump as a saturated oil injection hole, and the N+1th row of injection and production holes is connected to a meter as a saturated oil production hole, wherein N and N+1 are the sequence numbers of two adjacent rows in the vertical well pattern model, N is an odd number, and a few injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes;

[0026] Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and part of the formation water is driven out from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

[0027] In some optional embodiments, crude oil is injected into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are alternately arranged at intervals until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model capable of simulating the formation conditions of the oil reservoir to be tested, including:

[0028] According to the arrangement of the injection and production holes in the vertical well pattern model, one of the adjacent injection and production holes is used as a saturated oil injection hole and the other as a saturated oil production hole, the saturated oil injection hole is connected to a displacement pump, and the saturated oil production hole is connected to a meter;

[0029] Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and formation water is driven to be discharged from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

[0030] In a second aspect, an embodiment of the present invention provides a method for testing lateral broadband fracturing in a vertical well, comprising:

[0031] Water drive oil recovery experiments were conducted on a pre-established vertical well conventional fracturing experimental model and a vertical well lateral broadband fracturing experimental model, respectively; the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model were manufactured using the vertical well volume fracturing experimental model manufacturing method described above;

[0032] For the vertical well conventional fracturing test model and the vertical well lateral broadband fracturing test model, at least one of the following characteristic parameters is determined: oil displacement efficiency is determined based on the recorded water yield and oil yield of the oil production hole, pressure sweep range is determined based on the pressure value obtained at the pressure measurement point, and oil saturation is determined based on the resistivity value obtained at the resistivity measurement point;

[0033] Whether the oil reservoir to be tested is suitable for broadband fracturing is determined based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

[0034] In some optional embodiments, determining the oil recovery efficiency based on the recorded water yield and oil yield of the oil production hole includes:

[0035] The water output and oil output of the oil production hole at different times are recorded, and a displacement efficiency comparison chart is drawn based on the water output and oil output at different times to obtain the displacement efficiency at different times.

[0036] In some optional embodiments, determining the pressure range according to the pressure value obtained at the pressure measurement point includes:

[0037] The pressure values ​​obtained at each of the pressure measurement points at different times are recorded, and a pressure distribution isobaric map is drawn according to the pressure values ​​of each of the pressure measurement points at different times. The pressure sweep range is obtained according to the pressure distribution isobaric map.

[0038] In some optional embodiments, determining the oil saturation based on the resistivity value obtained at the resistivity measurement point includes:

[0039] The resistivity value obtained at each resistivity measurement point is recorded, and the oil saturation at the corresponding point of the model is converted based on the resistivity value obtained at each resistivity measurement point.

[0040] In a third aspect, an embodiment of the present invention provides a vertical well lateral broadband fracturing testing device, comprising:

[0041] The test data acquisition module is used to obtain experimental data of water drive oil production experiments in pre-established vertical well conventional fracturing experimental models and vertical well lateral broadband fracturing experimental models; the vertical well conventional fracturing experimental model and vertical well lateral broadband fracturing experimental model are manufactured using the vertical well volume fracturing experimental model manufacturing method as described above.

[0042] The characteristic parameter acquisition module is used to determine at least one of the following characteristic parameters based on the experimental data for the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model: determine the oil recovery efficiency based on the recorded water yield and oil yield of the oil production hole, determine the pressure sweep range based on the pressure value obtained at the pressure measurement point, and determine the oil saturation based on the resistivity value obtained at the resistivity measurement point.

[0043] The broadband fracturing analysis module is used to determine whether the oil reservoir to be tested is suitable for broadband fracturing based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

[0044] In a fourth aspect, an embodiment of the present invention provides a vertical well volume fracturing experimental model, which is manufactured using the vertical well volume fracturing experimental model manufacturing method as described above.

[0045] In a fifth aspect, an embodiment of the present invention provides an application of the aforementioned method for preparing a vertical well volume fracturing experimental model in preparing a vertical well volume fracturing experimental model.

[0046] In a sixth aspect, an embodiment of the present invention provides an application of the aforementioned vertical well lateral broadband fracturing test method in a vertical well lateral broadband fracturing applicability test.

[0047] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0048] An embodiment of the present invention provides a method for making a vertical well volume fracturing experimental model. When making the experimental model, the saturated formation water in the model is first treated, and then the model is saturated with oil through asynchronous injection and production until the crude oil content reaches a saturation state, so that the formation water and crude oil contents in the experimental core are closer to the real oil reservoir, and an experimental model that is closer to the real oil reservoir conditions is obtained. Compared with the physical simulation model obtained by single-phase displacement treatment, this model can better simulate the real oil reservoir conditions, has a stronger simulation ability for actual conditions, and can simulate a more realistic field environment, thereby improving the accuracy and applicability of the next experiment.

[0049] An embodiment of the present invention provides a vertical well lateral broadband fracturing test method. By collecting test data such as pressure values, resistivity values, oil production and water production obtained from water flooding experiments on a vertical well conventional fracturing test model and a vertical well lateral broadband fracturing test model, one or more characteristic parameters such as oil displacement efficiency, pressure sweep range, and oil saturation are selected to determine whether the reservoir to be tested is suitable for broadband fracturing. Conclusions on whether broadband fracturing is suitable can be drawn from different angles and compared and verified with each other. This is more reliable than conclusions drawn solely based on pressure values, thereby improving the reliability and accuracy of vertical well lateral broadband fracturing tests.

[0050] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0051] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0053] Figure 1 This is a flow chart of a method for preparing a vertical well volume fracturing experimental model in an embodiment of the present invention;

[0054] Figure 2a This is a distribution diagram of injection and production holes and pressure measurement points in a conventional fracturing model in an embodiment of the present invention;

[0055] Figure 2b This is a distribution diagram of injection and production holes and pressure measurement points in a broadband fracturing model according to an embodiment of the present invention;

[0056] Figure 3a This is a physical picture of a conventional fracturing model in an embodiment of the present invention;

[0057] Figure 3b This is a physical picture of the broadband fracturing model in an embodiment of the present invention;

[0058] Figure 4 Schematic diagram of multi-point vacuum saturation water in an embodiment of the present invention;

[0059] Figure 5a Schematic diagram of a row-type saturated oil injection and production experiment in an embodiment of the present invention;

[0060] Figure 5b Schematic diagram of cross-injection and saturated oil experiment in an embodiment of the present invention;

[0061] Figure 6 A flowchart of a specific implementation process of the method for making a vertical well volume fracturing experimental model in an embodiment of the present invention;

[0062] Figure 7 Schematic diagram of a broadband fracturing well pattern in an embodiment of the present invention;

[0063] Figure 8 A schematic diagram of a connectivity test in an embodiment of the present invention;

[0064] Figure 9 This is a flow chart of a method for testing lateral broadband fracturing in a vertical well according to an embodiment of the present invention;

[0065] Figure 10 This is a flowchart of a specific implementation process of a vertical well lateral broadband fracturing test method according to an embodiment of the present invention;

[0066] Figure 11a This is a 5-hour pressure distribution diagram of conventional fracturing displacement in an embodiment of the present invention;

[0067] Figure 11b This is a pressure distribution diagram of conventional fracturing displacement for 18 hours in an embodiment of the present invention;

[0068] Figure 11c This is a 47-hour pressure distribution diagram of conventional fracturing displacement in an embodiment of the present invention;

[0069] Figure 11d This is a 78-hour pressure distribution diagram of conventional fracturing displacement in an embodiment of the present invention;

[0070] Figure 12a This is a 5-hour pressure distribution diagram of broadband fracturing displacement in an embodiment of the present invention;

[0071] Figure 12b This is a pressure distribution diagram for 18 hours of broadband fracturing displacement in an embodiment of the present invention;

[0072] Figure 12c This is a 47-hour pressure distribution diagram of broadband fracturing displacement in an embodiment of the present invention;

[0073] Figure 12d This is a 78-hour pressure distribution diagram of broadband fracturing displacement in an embodiment of the present invention;

[0074] Figure 13 A comparison chart of oil displacement efficiency between a conventional fracturing model and a broadband fracturing model in an embodiment of the present invention;

[0075] Figure 14 This is a block diagram of a vertical well lateral broadband fracturing test device in an embodiment of the present invention. DETAILED DESCRIPTION

[0076] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0077] In order to solve the problems existing in the prior art, an embodiment of the present invention provides a method.

[0078] Example 1

[0079] The first embodiment of the present invention provides a method for preparing a vertical well volume fracturing experimental model, the process of which is as follows: Figure 1 As shown, the following steps are included:

[0080] Step S11: Using a core plate to create a vertical well pattern model; the vertical well pattern model includes fractures and multiple injection and production holes arranged according to the well pattern form, volume fracturing type and parameters of the oil reservoir to be tested, as well as pressure measurement points and / or resistivity measurement points. The multiple injection and production holes include at least one injection hole for an oil recovery test and at least one oil recovery test production hole;

[0081] Collect rock cores and process them into core slabs of the size required for the vertical well pattern model;

[0082] According to the well pattern, volume fracturing type and parameters of the reservoir to be tested, determine how to arrange fractures and injection and production holes on the core plate to better simulate real fractures and oil production wells, as well as how to arrange pressure measurement points and resistivity measurement points to better measure pressure and resistivity data. The similarity criteria and similarity principles of physical simulation of water flooding in oil reservoirs can be used to convert the well pattern and volume fracturing parameters of the reservoir to be tested to match the size of the core model, and obtain the parameters of the vertical well pattern model; wherein the well pattern of the reservoir to be tested includes the distance between wells and the positional relationship of oil production wells, the volume fracturing type includes conventional fracturing and width fracturing, the volume fracturing parameters include the number of fractures, fracture length, fracture width, etc., and the parameters of the vertical well pattern model include the positional relationship and the distance between the injection and production holes to be arranged in the model, the volume fracturing type to be simulated, the number of fractures to be arranged, the fracture length, the fracture width, etc.

[0083] According to the parameters of the vertical well pattern model, the injection and production holes, number of fractures, fracture length and fracture width of the vertical well pattern model are designed; the designed fractures and injection and production holes refer to Figure 2a and Figure 2b As shown, Figure 2a This is an example diagram of the vertical well pattern model design when the volume fracturing type is conventional fracturing. Figure 2b This is an example diagram of the vertical well pattern model design when the volume fracturing type is broadband fracturing. The black solid circles represent injection and production holes. The injection and production holes marked "injection point" in the upper right corner are injection holes for oil displacement test, and the injection and production holes marked "production point" in the upper left corner and the middle are production holes for oil displacement test. Figure 2a For conventional fracturing, the fracturing crack is represented by a crack in the model. Figure 2b For broadband fracturing cracks, the fracturing cracks are represented by parallel cracks and vertical cracks in the model. Vertical cracks are used to represent secondary cracks produced by lateral fracturing, which are closer to the actual situation than parallel cracks.

[0084] According to the well pattern of the reservoir to be tested, deep holes are drilled in the designated corners and the middle of the cracks of the core plate, and shallow holes are drilled at the pressure measurement points;

[0085] The deep hole includes at least one injection hole for oil displacement test and at least one production hole for oil displacement test.

[0086] According to observation needs, the positions of pressure monitoring points and resistivity monitoring points are designed at different locations on the model;

[0087] Fractures were placed around the production holes on two core plates to simulate conventional fracturing and broadband fracturing, respectively. Fractures were placed around the production holes to simulate broadband fracturing, and the fracture length and width were designed based on the similarity principle, which is derived from the similarity criteria used in physical simulations of water flooding in oil reservoirs.

[0088] Reference for vertical well pattern model for arranging fractures and injection and production holes Figure 3a and Figure 3b As shown, Figure 3a It is a conventional fracturing model. Figure 3b It is a width fracturing model.

[0089] Step S12: vacuuming the vertical well pattern model, selecting at least one injection and production hole as a saturated water hole to inject formation water into the model until it reaches a saturated state;

[0090] The model is vacuumed to allow it to absorb formation water to a naturally saturated state. Due to the large size and low permeability of the outcrop model, only the reserved injection and production holes are connected to the outside world after the model is encapsulated. Conventional methods cannot vacuum and saturate large models with water. Therefore, a multi-point vacuuming and saturation method is used.

[0091] From the injection and production holes, multiple holes are selected as vacuum points, at least one saturated water point is selected, the vacuum points are connected, the core model is vacuumed to a preset vacuum state, and then the saturated water point is connected to formation water to a water saturated state;

[0092] For example, two injection and production holes are reserved at both ends of the model and vacuum gauges are installed to observe changes in vacuum level. Multiple injection and production holes are selected as vacuum points and vacuum is performed to ensure high vacuum levels at different locations. At least one injection and production hole is reserved as a saturated water point.

[0093] For example, refer to Figure 4 As shown, the core slab was vacuumed. Multiple holes were selected as vacuum points, ensuring high vacuum levels at all locations. To monitor changes in vacuum levels, vacuum gauges were installed at two injection and production holes at each end of the core slab as vacuum monitoring points. Two holes were reserved as saturation points.

[0094] The saturated water point is connected to the formation water through a pipe. For example, at atmospheric pressure, formation water enters the evacuated pores of the model. When the overall vacuum level of the model returns to atmospheric pressure, the model reaches full saturation.

[0095] Step S13: Crude oil is injected into the vertical well pattern model in a row-like injection-production manner, with one row of injection-production holes serving as saturated oil injection holes and the other row of injection-production holes serving as saturated oil production holes, until the saturated oil production holes change from discharging water to discharging only oil. This process is called row-like injection-production, and is referred to as Figure 5a The diagram shows a row of injection and production pipes connected vertically. Row injection and production refers to injection in one row of holes and production in another. The oil saturation process is essentially oil displacing water. When no more water can be displaced by row injection, cross-injection is used until oil saturation is achieved.

[0096] Step S14: Crude oil is injected into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are arranged alternately and at intervals until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model that can simulate the formation conditions of the oil reservoir to be tested.

[0097] Cross-injection and production refers to the arrangement of the injection and production holes in the vertical well pattern model, where one adjacent injection and production hole is used as a saturated oil injection hole and the other as a saturated oil production hole. The saturated oil injection hole is connected to a displacement pump, and the saturated oil production hole is connected to a meter. A small number of injection and production holes (for example, those that are scattered and difficult to be assigned to a certain row) can be freely set as saturated oil injection holes or saturated oil production holes.

[0098] Cross-injection reference Figure 5b The cross-injection and production pipelines shown in the figure are connected in a row vertically and in a column horizontally. The first row from the left has injection and production holes numbered 2, 14, and 18. Production 2 is connected to the displacement pump and is a saturated oil injection hole. The injection and production holes adjacent to Production 2 in the horizontal and vertical directions are 13 and 14. Then, 13 and 14 adjacent to Production 2 are saturated oil production holes, and 13 and 14 are connected to the meter. Because 13 is a saturated oil production hole, and the injection and production holes adjacent to 13 in the horizontal and vertical directions are Production 2, 12, and 9, then Production 2, 12, and 9 are all saturated oil injection holes, and Production 2, 12, and 9 are connected to the displacement pump. Most of the injection and production holes are connected to the displacement pump or meter according to the above rules, becoming saturated oil injection holes or saturated oil production holes. A few injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes, for example Figure 5b The middle injection and production hole 4 is connected to the displacement pump and is a saturated oil injection hole. The injection and production holes adjacent to 4 in the horizontal and vertical directions are 8, 7, and 8. Among them, 8 and 7 are saturated oil production holes, which are arranged alternately with 4. 7 is a saturated oil injection hole and does not alternate with 4.

[0099] The methods of step S13 and step S14 constitute asynchronous injection and production.

[0100] Through experiments comparing the oil saturation effects of single-phase displacement and asynchronous injection and production, the experimental data showed that the saturated oil volume was 120ml by row injection and production, while the saturated oil volume was 140ml by cross injection and production, an increase of 20ml in saturation and 7% in oil saturation.

[0101] Since row injection and production is only a single-phase displacement, it has great limitations in simulating actual conditions. Therefore, it is necessary to adopt an asynchronous injection and production method. That is, after row injection and production, cross injection and production are used to increase the oil saturation of the model and simulate a more realistic field environment.

[0102] Through asynchronous injection and production, the model is saturated with oil to the original oil saturation of the formation. Compared with the physical simulation model of water-driven single-phase vertical well broadband fracturing, the physical simulation model provided by the present invention has a stronger simulation ability of the actual situation and can simulate a more realistic field environment, thereby improving the accuracy and applicability of the next experiment.

[0103] Example 2

[0104] The second embodiment of the present invention provides a specific implementation process of a method for making a vertical well volume fracturing experimental model, the process of which is as follows: Figure 6 As shown, the following steps are included:

[0105] Step S21: Determine the type and parameters of the fractures to be arranged according to the volume fracturing type and parameters of the reservoir to be tested, and arrange the fractures on the core plate; the volume fracturing types include conventional fracturing and broadband fracturing; the fracture types include conventional fracturing fractures and broadband fracturing fractures;

[0106] For example, the actual width of broadband fracturing and the well pattern of the reservoir to be tested are as follows: Figure 7 As shown, dots represent wells, 500m, 150m and 273m are the straight-line distances between wells, 30-40m is the width of conventional fracturing cracks, 60-80m is the width of wide-band fracturing cracks, and old cracks refer to the conventional fracturing method used when old wells started production. During the production process, it was found that the crack width was narrow and the residual oil on both sides could not be affected. Later, wide-band fracturing was used to perform secondary fracturing on the old wells.

[0107] Collect rock cores and process them into core slabs of preset size for vertical well pattern model;

[0108] According to the well pattern, volume fracturing type and parameters of the reservoir to be tested, determine how to arrange fractures and injection and production holes on the core plate to better simulate real fractures and oil production wells, as well as how to arrange pressure measurement points and resistivity measurement points to better measure pressure and resistivity data. The similarity criteria and similarity principles of physical simulation of water flooding in oil reservoirs can be used to convert the well pattern and volume fracturing parameters of the reservoir to be tested to match the size of the core model, and obtain the parameters of the vertical well pattern model; wherein the well pattern of the reservoir to be tested includes the distance between wells and the positional relationship of oil production wells, the volume fracturing type includes conventional fracturing and width fracturing, the volume fracturing parameters include the number of fractures, fracture length, fracture width, etc., and the parameters of the vertical well pattern model include the positional relationship and the distance between the injection and production holes to be arranged in the model, the volume fracturing type to be simulated, the number of fractures to be arranged, the fracture length, the fracture width, etc.

[0109] In some optional embodiments, the fracture type, number, length and width to be arranged are determined according to the volume fracturing type and the number, length and width of the fractures in the reservoir to be tested and the fractures are arranged on the core plate according to the scaling rules.

[0110] For example, fractures were placed around the production holes in two vertical well pattern models to simulate conventional fracturing and broadband fracturing, respectively. Fractures were placed around the production holes to simulate broadband fracturing, and the fracture length and width were designed based on the similarity principle. This similarity principle, derived from the similarity criteria used in physical simulations of water flooding in oil reservoirs, determines the relationship between model parameters and reservoir parameters.

[0111] The vertical well pattern model for arranging fractures and injection and production holes is as follows: Figure 3a and Figure 3b As shown, Figure 3a It is a conventional fracturing model. Figure 3b It is a width fracturing model.

[0112] Step S22: Determine the locations of injection and production holes according to the well pattern of the reservoir to be measured and the locations of the selected pressure measurement points, and arrange the injection and production holes; wherein the injection and production holes arranged at the pressure measurement points are shallow holes, and the injection and production holes at other locations are deep holes;

[0113] According to the parameters of the vertical well pattern model, the injection and production holes, number of fractures, fracture length and fracture width of the vertical well pattern model are designed; the designed fractures and injection and production holes refer to Figure 2a and Figure 2b As shown, the black solid dots represent injection and production holes. The injection and production hole marked "injection point" in the upper right corner is the injection hole for oil displacement test, and the injection and production holes marked "production point" in the upper left corner and the middle are the oil displacement test production holes. Figure 2a For conventional fracturing, the fracturing crack is represented by a crack in the model. Figure 2b For broadband fracturing cracks, the fracturing cracks are represented by parallel cracks and vertical cracks in the model. Vertical cracks are used to represent secondary cracks produced by lateral fracturing, which are closer to the actual situation than parallel cracks.

[0114] In some optional embodiments, deep holes are drilled in designated corners and middle positions of cracks of the core plate according to the well pattern of the reservoir to be measured, and shallow holes are drilled at pressure measurement points;

[0115] The deep hole includes at least one injection hole for oil displacement test and at least one production hole for oil displacement test.

[0116] For example, deep holes were drilled in the upper left and right corners of the vertical well pattern model, as well as in the middle of the fracture. These included at least one injection hole and at least one production hole for the flooding test. To minimize the impact of pressure measurement points on the seepage field and to facilitate model creation, shallow holes were drilled at the pressure measurement points.

[0117] In some optional embodiments, the deep holes and shallow holes are cleaned and dried to obtain arranged injection and production holes.

[0118] After rinsing the stone chips generated during the drilling process with water and allowing the water on the model surface to evaporate naturally, place the model in a constant temperature chamber for several hours. Remove the model from the constant temperature chamber and allow it to cool naturally to room temperature in the open air. For example, after rinsing the stone chips generated during the previous drilling step with water, allow it to cool for a period of time before placing it in a constant temperature chamber for 24 hours to accelerate the evaporation of residual water and remove any moisture from the model that may affect the experiment. The temperature inside the constant temperature chamber can be set between 80°C and 100°C.

[0119] Step S23: arranging pressure measuring equipment at the pressure measuring point and / or arranging resistivity measuring equipment at the resistivity measuring point, installing injection-production well joints for the injection-production holes, and filling the fractures;

[0120] According to observation needs, the positions of pressure monitoring points and resistivity monitoring points are designed at different locations on the model;

[0121] Arranging a pressure measuring device at a pressure measuring point and / or arranging a resistivity measuring device at a resistivity measuring point, installing an injection-production well joint for the injection-production hole, and filling the fracture;

[0122] For example, the pressure measuring device can be a pressure sensor, and the resistivity measuring device can be a resistivity strain gauge. The data of the pressure measuring device and the resistivity measuring device can be read in real time by a computer, and the pressure value and the corresponding time, the resistivity value and the corresponding time are recorded. Mix quartz sand of a certain mesh size with glue. The glue needs to not crack during the process of heating and pressurization. Not all glues can achieve the above effect. The process of selecting glue requires a lot of experiments to test whether the performance of the glue will not crack during the process of heating and pressurization. In the embodiment of the present invention, after a lot of experiments and comparison of the results, epoxy resin adhesive is selected as the glue. The mixture of quartz sand and glue is evenly filled into the cracks.

[0123] Step S24: sealing the core plate to obtain a vertical well pattern model.

[0124] For example, marble glue is used to seal the upper and lower ends of the fracture. The pressure sensor and the injection and production well connectors are also glued to the corresponding boreholes using marble glue. The resistivity strain gauge is attached to the back of the model and sealed securely. This prevents the glue used to seal the model from flowing into the borehole and interfering with the experiment. The mold for the encapsulated model is assembled, and the model is placed in the mold and sealed with the glue used to seal the model. After the model solidifies, the mold is removed to create the vertical well pattern model.

[0125] Steps S21-S24 implement the production of a vertical well pattern model using a core plate.

[0126] Step S25: Detecting the connectivity of each injection and production hole in the vertical well pattern model;

[0127] For example, a nitrogen cylinder is used to test the connectivity between the injection-production holes and the pressure measurement holes to avoid incorrect judgment of the experimental results caused by blocking the pressure measurement points and injection-production points during the model making process. As Figure 8 shown, represents a valve. The dots marked with "Production 1" and "Production 2" etc. represent the oil production holes for the oil displacement test, and the dot marked with "Injection" represents the injection hole for the oil displacement test. The horizontal line passing through the dot of "Production 1" represents a fracture, and the number closest to the dot is the number of the hole represented by the dot. In the figure, the intermediate container is used to hold oil and water, and the corresponding valve is opened for the fluid used. The function of the fluid meter is to measure the liquid output. If the experimental time is short and the liquid output is small, a micro flow meter is used with high precision. When the liquid output is large and the time is long, an automatic fluid collection device is used. The function of the pressure patrol instrument is to connect the computer with the pressure sensor, and the data can be automatically saved to the computer. If the valve in the figure is opened, the fluid meter records that fluid flows out, and the pressure patrol instrument detects an increase in pressure. When the valve is closed, the fluid flow stops and the pressure decreases, then it is judged that the connectivity is normal.

[0128] If the connectivity is normal, vacuum treatment is carried out.

[0129] Step S26: If the connectivity is normal, reserve at least one injection-production hole as a saturated water hole, at least one injection-production hole as a vacuum monitoring point, and use the other injection-production holes as vacuum extraction points. Vacuum the vertical well pattern model through the vacuum extraction points. When it is determined according to the detection results of the vacuum monitoring points that the vacuum degree reaches the requirement, inject formation water into the model through the saturated water hole until the formation water is absorbed by the vertical well pattern model to the saturated state.

[0130] Vacuum the vertical well pattern model, and select at least one injection-production hole as a saturated water hole to inject formation water into the model until it reaches the saturated state;

[0131] Vacuum the model so that the model can inhale formation water to the natural saturated state. Since the outcrop model has a large volume and low permeability, only the reserved injection-production holes are connected to the outside after the model is encapsulated, and the conventional method cannot vacuum and saturate the large model. Therefore, the method of multi-point vacuum saturation is adopted.

[0132] From the injection-production holes, select multiple holes as vacuum extraction points, select at least one hole as a saturated water point, connect the vacuum extraction points, vacuum the core model to the preset vacuum state, and then connect the saturated water point to the formation water until it reaches the water-saturated state;

[0133] For example, keep two injection-production holes at both ends of the model to install vacuum gauges to observe the change of the vacuum degree. Select multiple injection-production holes as vacuum extraction points for vacuuming to ensure that the vacuum degree at different positions is very high, and reserve at least one injection-production hole as a saturated water point.

[0134] For example, Figure 4 As shown, the core slab was vacuumed. Multiple holes were selected as vacuum points, ensuring high vacuum levels at all locations. To monitor changes in vacuum levels, vacuum gauges were installed at two injection and production holes at each end of the core slab as vacuum monitoring points. Two holes were reserved as saturation points.

[0135] The saturated water point is connected to the formation water through a pipe. For example, at atmospheric pressure, formation water enters the evacuated pores of the model. When the overall vacuum level of the model returns to atmospheric pressure, the model reaches full saturation.

[0136] Step S27: Crude oil is injected into the vertical well pattern model in a row-shaped injection and production method, with one row of injection and production holes serving as saturated oil injection holes and the other row of injection and production holes serving as saturated oil production holes, until the saturated oil production holes change from discharging water to discharging only oil. This step is called row-shaped injection and production, and is referred to as row-shaped injection and production. Figure 5a The diagram shows the pipe connections for row-type injection and production. Row-type injection and production refers to injection in a row of holes and production in a row of holes. The oil saturation process is essentially the process of using oil to displace water. When row-type injection and production runs out of water, cross-type injection and production are used until no more water is displaced, achieving oil saturation. The model is placed in a high-pressure holder in a large outcrop model to saturate it with oil.

[0137] In some optional embodiments, crude oil is injected into the vertical well pattern model in a row-type injection-production manner, wherein one row of injection-production holes serves as saturated oil injection holes and another row of injection-production holes serves as saturated oil production holes, until the saturated oil production holes change from discharging water to discharging only oil, including:

[0138] The Nth row of injection and production holes in the vertical well pattern model is connected to a displacement pump as a saturated oil injection hole, and the N+1th row of injection and production holes is connected to a meter as a saturated oil production hole, wherein N and N+1 are the sequence numbers of two adjacent rows in the vertical well pattern model, N is an odd number, and a few injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes;

[0139] Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and part of the formation water is driven out from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

[0140] Step S28: Crude oil is injected into the vertical well pattern model in a cross-injection and production manner with saturated oil injection holes and saturated oil production holes arranged alternately and at intervals, until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model that can simulate the formation conditions of the oil reservoir to be tested. Figure 5b The cross-injection pipeline connection is shown. The model is placed in a large outcrop model high-pressure holder saturated with oil.

[0141] In some optional embodiments, crude oil is injected into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are alternately arranged at intervals until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model capable of simulating the formation conditions of the oil reservoir to be tested, including:

[0142] According to the arrangement of the injection and production holes in the vertical well pattern model, one of the adjacent injection and production holes is used as a saturated oil injection hole and the other as a saturated oil production hole. The saturated oil injection hole is connected to a displacement pump, and the saturated oil production hole is connected to a meter. A few injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes.

[0143] Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and formation water is driven to be discharged from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

[0144] Cross injection and production refers to the arrangement of the injection and production holes in the vertical well pattern model, where one adjacent injection and production hole is used as a saturated oil injection hole and the other as a saturated oil production hole. The saturated oil injection hole is connected to a displacement pump, and the saturated oil production hole is connected to a meter. A small number of injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes.

[0145] Cross-injection reference Figure 5b The cross-injection and production pipelines shown in the figure are connected in a row vertically and in a column horizontally. The first row from the left has injection and production holes numbered 2, 14, and 18. Production 2 is connected to the displacement pump and is a saturated oil injection hole. The injection and production holes adjacent to Production 2 in the horizontal and vertical directions are 13 and 14. Then, 13 and 14 adjacent to Production 2 are saturated oil production holes, and 13 and 14 are connected to the meter. Because 13 is a saturated oil production hole, and the injection and production holes adjacent to 13 in the horizontal and vertical directions are Production 2, 12, and 9, then Production 2, 12, and 9 are all saturated oil injection holes, and Production 2, 12, and 9 are connected to the displacement pump. Most of the injection and production holes are connected to the displacement pump or meter according to the above rules, becoming saturated oil injection holes or saturated oil production holes. A few injection and production holes can be freely set as saturated oil injection holes or saturated oil production holes, for example Figure 5b The middle injection and production hole 4 is connected to the displacement pump and is a saturated oil injection hole. The injection and production holes adjacent to 4 in the horizontal and vertical directions are 8, 7, and 8. Among them, 8 and 7 are saturated oil production holes, which are arranged alternately with 4. 7 is a saturated oil injection hole and does not alternate with 4.

[0146] Among them, the method of step S27 and step S28 constitutes asynchronous injection and production.

[0147] Through experiments comparing the oil saturation effects of single-phase displacement and asynchronous injection and production, the experimental data showed that the saturated oil volume was 120ml by row injection and production, while the saturated oil volume was 140ml by cross injection and production, an increase of 20ml in saturation and 7% in oil saturation.

[0148] Since row injection and production is only a single-phase displacement, it has great limitations in simulating actual conditions. Therefore, it is necessary to adopt an asynchronous injection and production method. That is, after row injection and production, cross injection and production are used to increase the oil saturation of the model and simulate a more realistic field environment.

[0149] Through asynchronous injection and production, the model is saturated with oil to the original oil saturation of the formation. Compared with the physical simulation model of water-driven single-phase vertical well broadband fracturing, the physical simulation model provided by the present invention has a stronger simulation ability of the actual situation and can simulate a more realistic field environment, thereby improving the accuracy and applicability of the next experiment.

[0150] Example 3

[0151] The third embodiment of the present invention provides a method for testing lateral broadband fracturing of a vertical well, the process of which is as follows: Figure 9 As shown, the following steps are included:

[0152] Step S31: conducting water drive oil production experiments in the pre-established vertical well conventional fracturing experimental model and vertical well lateral broadband fracturing experimental model respectively; the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model are manufactured using the vertical well volume fracturing experimental model manufacturing method as described above.

[0153] Step S32: For the vertical well conventional fracturing test model and the vertical well lateral broadband fracturing test model, respectively determine at least one of the following characteristic parameters: determine the oil recovery efficiency based on the recorded water yield and oil yield of the oil production hole, determine the pressure sweep range based on the pressure value obtained at the pressure measurement point, and determine the oil saturation based on the resistivity value obtained at the resistivity measurement point.

[0154] The oil recovery efficiency is determined based on the recorded water output and oil output of the oil production hole. The water output and oil output of the oil production hole can be recorded at different times, and an oil recovery efficiency comparison chart is drawn based on the water output and oil output at different times to obtain the oil recovery efficiency at different times.

[0155] A fluid meter is used to automatically collect the water output and oil output and record the data, and a computer is used to automatically collect the pressure value and resistivity value and save the data. For example, the fluid meter can be an automatic liquid collector. This device is an innovative system for this physical simulation experiment. In the past, the collection of liquid output was done manually. Compared with the water flooding of small cores, the water flooding process of large models takes a long time and consumes manpower. In addition, due to negligence, the metering may be untimely, and the optimal data recording time may be missed. In order to solve the above problems, the embodiment of the present invention adopts an automatic liquid collection system, which can set the time for collecting the liquid output according to the needs of the experiment. After the collection is completed in each time period, the liquid outlet pipe can be automatically moved to collect the liquid output in the next time period. It can save manpower and ensure that key data collection is completed on time and as needed, thereby improving the reliability of experimental data.

[0156] The pressure wave range is determined based on the pressure values ​​obtained at the pressure measurement points. The pressure values ​​obtained at each pressure measurement point at different times can be recorded, and a pressure distribution isobaric line diagram is drawn based on the pressure values ​​of each pressure measurement point at different times. The pressure wave range is obtained based on the pressure distribution isobaric line diagram.

[0157] The oil saturation is determined based on the resistivity values ​​obtained at the resistivity measurement points. The resistivity values ​​obtained at the resistivity measurement points may be recorded, and the oil saturation at the corresponding point of the model may be converted based on the resistivity values ​​obtained at the resistivity measurement points.

[0158] A pressure measuring device is used to obtain pressure values ​​at different pressure measurement points at different times. The pressure measuring device can be a pressure sensor. A resistivity measuring device is used to obtain resistivity values ​​at different resistivity measurement points. The resistivity measuring device can be a resistivity strain gauge. The data from the pressure measuring device and the resistivity measuring device can be read by a computer in real time, and the pressure value and the corresponding time, and the resistivity value and the corresponding time are recorded.

[0159] Step S33: judging whether the reservoir to be tested is suitable for broadband fracturing based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

[0160] For example, compare the pressure sweep range, oil recovery efficiency, and oil saturation of conventional and broadband fracturing models. If the broadband fracturing model has a larger pressure sweep range, higher oil recovery efficiency, and lower oil saturation, then broadband fracturing will have a better oil recovery effect and higher recovery rate in the oil field under test, and the oil field under test is suitable for broadband fracturing.

[0161] Judgments can be made based on one or more of the following parameters: pressure sweep range, oil displacement efficiency, and oil saturation. When multiple parameters are combined, more accurate results can be obtained, and these can be mutually verified. For example, if only the pressure impact range is observed, the test can only be conducted based on the pressure sweep range, lacking verification of the test results, resulting in significant uncertainty and lacking support for enhanced oil recovery analysis. By collecting pressure values, resistivity values, oil yield, and water yield, it is possible to draw conclusions from multiple perspectives on whether broadband fracturing is suitable, and to compare and verify these results. This is more reliable than conclusions drawn solely based on pressure values, improving the reliability and accuracy of vertical well lateral broadband fracturing tests. Furthermore, by analyzing oil displacement efficiency, enhanced oil recovery can be analyzed. The embodiments of the present invention utilize an automatic liquid collection system to count water and oil yields. The time for collecting liquid yields can be set according to experimental needs. After each time period is completed, the liquid outlet pipe can be automatically moved to collect liquid yields for the next time period. This saves manpower and ensures that key data collection is completed on time and as needed, improving the reliability of experimental data.

[0162] Example 4

[0163] The fourth embodiment of the present invention provides a specific implementation process of a vertical well lateral broadband fracturing test method, which determines whether the reservoir to be tested is suitable for broadband fracturing by using multiple parameters such as oil displacement efficiency, pressure sweep range, and oil saturation. The process is as follows: Figure 10 As shown, the following steps are included:

[0164] Step S41: Establishing a vertical well conventional fracturing experimental model and a vertical well lateral broadband fracturing experimental model, wherein the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model are prepared using the vertical well volume fracturing experimental model preparation method described above.

[0165] Step S42: performing water drive oil production experiments in the pre-established vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model respectively.

[0166] Step S43: Record the water output and oil output, pressure value, and resistivity value at different times.

[0167] In some optional embodiments, the water output and oil output of the oil production hole at different moments are recorded, and a displacement efficiency comparison chart is drawn based on the water output and oil output at different moments to obtain the displacement efficiency at different moments.

[0168] A pressure measuring device is used to obtain pressure values ​​at different pressure measurement points at different times. The pressure measuring device can be a pressure sensor. A resistivity measuring device is used to obtain resistivity values ​​at different resistivity measurement points. The resistivity measuring device can be a resistivity strain gauge. The data from the pressure measuring device and the resistivity measuring device can be read by a computer in real time, and the pressure value and the corresponding time, and the resistivity value and the corresponding time are recorded.

[0169] Use a fluid meter to automatically collect water and oil output and record the data, and use a computer to automatically collect pressure and resistivity values ​​and save the data.

[0170] For example, the fluid meter can be an automatic liquid collector. This device is an innovative system for this physical simulation experiment. In the past, the collection of liquid output was done manually. Compared with water flooding in small cores, the water flooding process of large models takes a long time and consumes manpower. In addition, due to negligence, metering may be delayed, and the optimal data recording time may be missed. To solve the above problems, the embodiment of the present invention adopts an automatic liquid collection system. The time for collecting liquid output can be set according to the needs of the experiment. After the collection is completed in each time period, the liquid outlet pipe can be automatically moved to collect the liquid output in the next time period. It can save manpower and ensure that key data collection is completed on time and as needed, thereby improving the reliability of experimental data.

[0171] Step S44: determining the oil displacement efficiency based on the recorded water and oil yields of the oil production holes, determining the pressure sweep range based on the pressure values ​​obtained at the pressure measurement points, and determining the oil saturation based on the resistivity values ​​obtained at the resistivity measurement points.

[0172] The water output and oil output of the oil production hole at different times are recorded, and a displacement efficiency comparison chart is drawn based on the water output and oil output at different times to obtain the displacement efficiency at different times.

[0173] In some optional embodiments, the pressure values ​​obtained at each of the pressure measurement points at different times are recorded, and a pressure distribution isobaric map is drawn based on the pressure values ​​of each of the pressure measurement points at different times. Based on the pressure distribution isobaric map, the pressure wave range is obtained.

[0174] According to the pressure values ​​at different monitoring points at different times, the pressure distribution isobaric maps of the conventional fracturing model and the broadband fracturing model are drawn respectively.

[0175] According to the pressure values ​​at different monitoring points at different times, pressure distribution isobars of the conventional fracturing model and the broadband fracturing model are drawn respectively. According to the water and oil yields at different times, a comparison diagram of oil displacement efficiency is drawn.

[0176] In some optional embodiments, the resistivity value obtained at each resistivity measurement point is recorded, and the oil saturation at the corresponding point of the model is converted based on the resistivity value obtained at each resistivity measurement point.

[0177] Step S45: judging whether the reservoir to be tested is suitable for broadband fracturing based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

[0178] For example, compare the pressure sweep range, oil recovery efficiency, and oil saturation of conventional and broadband fracturing models. If the broadband fracturing model has a larger pressure sweep range, higher oil recovery efficiency, and lower oil saturation, then broadband fracturing will have a better oil recovery effect and higher recovery rate in the oil field under test, and the oil field under test is suitable for broadband fracturing.

[0179] If the broadband fracturing model has a larger pressure sweep, higher oil recovery efficiency, and lower oil saturation than the conventional fracturing model, then broadband fracturing has a better recovery effect in the oil field under test and is suitable for broadband fracturing. If the broadband fracturing model has no significant advantages in pressure sweep, oil recovery efficiency, or oil saturation compared to the conventional fracturing model, then broadband fracturing has no better recovery effect than conventional fracturing and the effect of broadband fracturing in the oil field under test is not significant.

[0180] By collecting pressure values, resistivity values, oil production and water production, it is possible to draw conclusions on whether broadband fracturing is suitable from multiple perspectives and compare and verify them with each other. This is more reliable than conclusions drawn solely based on pressure values, and improves the reliability and accuracy of vertical well lateral broadband fracturing tests.

[0181] For example, based on the basic parameters of a well group in Changqing Oilfield, an indoor physical model of conventional fracturing and broadband fracturing was designed. Figure 11a 、 11b , 11c, 11d and Figure 12a 、 12b , 12c, 12d. Displacement experiments were also conducted and the pressure distribution measured was analyzed.

[0182] Figure 11a 、 11b , 11c, and 11d are pressure distribution contours of conventional fracturing. Figure 11a 、 11b , 11c, and 11d are the pressure distributions 5 hours, 18 hours, 47 hours, and 78 hours after the start of displacement, respectively. The horizontal and vertical coordinates on the isobaric graph represent the length, and the unit of the pressure value on the isobar and the isobar scale on the right is MPa. Figure 12a 、 12b , 12c, and 12d are the isobaric lines of width fracturing pressure distribution. Figure 12a 、 12b, 12c, and 12d are the pressure distributions 5 hours, 18 hours, 47 hours, and 78 hours after the start of displacement, respectively. The horizontal and vertical coordinates on the isobar graph represent the length, and the unit of the pressure value on the isobar and the isobar scale on the right is MPa.

[0183] Depend on Figure 11a 、 11b , 11c, 11d and Figure 12a 、 12b As can be seen in Figures 12c and 12d, as the seepage state changes from unsteady to steady, the pressure gradient near the injection well gradually decreases (the isobars in the upper right corner of the figure change from dense to sparse), while the pressure gradient near the production well gradually increases (the isobars change from sparse to dense). This is due to the presence of the starting pressure, which creates a local high-pressure zone near the injection well at the beginning of the displacement. As the flow time increases, the pressure gradually spreads toward the production well. The pressure preferentially propagates along the injection well and the front of the fracture, and then along the fracture toward the production well. The presence of the fracture is equivalent to shortening the seepage distance, which increases the pressure gradient around the fracture (the isobars around the fracture gradually become denser).

[0184] The nonlinear seepage curve is used to analyze the pressure range and degree of utilization during broadband fracturing. The nonlinear seepage curve determines the pressure at which oil in the model can be displaced, assuming the pressure at this point is P. Once pressure P is determined, the model's isobaric map is used to determine that oil below P cannot be mobilized, while oil above P can be mobilized. Regarding the nonlinear seepage curve, the following explanation is provided: in medium- and high-permeability reservoirs, due to the large pore size, the boundary layer occupies a very small proportion of the seepage space, and its impact on seepage can be ignored. However, in ultra-low permeability reservoirs, the fine pore throats and complex structure, coupled with the influence of clay minerals, significantly enhance the influence of the solid-liquid boundary layer on seepage. This results in a seepage pattern that deviates from the classic Darcy law, exhibiting nonlinear seepage characteristics. A curve reflecting these nonlinear seepage characteristics is called a nonlinear seepage curve.

[0185] By comparison Figure 11d and Figure 12d It can be seen that after 78 hours of displacement, the broadband fracturing model has a wider pressure range, a larger lateral pressure drop funnel, a greater degree of mobilization, more conducive to fluid recovery, and a shorter time to stabilization. Therefore, broadband fracturing has a better oil recovery effect in the tested oil field and is suitable for the tested oil field.

[0186] According to the water output and oil output at different times, the oil displacement efficiency of the two models is calculated respectively, and a comparison chart of the oil displacement efficiency of the two models is drawn.

[0187] Reference Figure 13As shown, the horizontal axis represents displacement time in hours, and the vertical axis represents oil displacement efficiency in %. The marked line represents the oil recovery efficiency of the conventional fracturing model. The marked line represents the oil recovery efficiency of the width fracturing model. Figure 13 As can be seen, within the first five hours of the two models, the recovery efficiency of conventional fracturing and broadband fracturing was similar. This was primarily due to the short displacement time, the limited waterflooding range in both models, and the primary source of produced oil near the main inlet. As the displacement time increased and the waterflooding range expanded, the effects of broadband fracturing gradually became apparent, the lateral distance affected by the fractures increased, and the recovery efficiency gradually improved. By the end of the displacement process, broadband fracturing had increased its recovery efficiency by 6.4% compared to conventional fracturing. This 6.4% improvement in recovery efficiency suggests that broadband fracturing offers a higher recovery factor than conventional fracturing. Therefore, broadband fracturing achieved better recovery results in the test field, making it a suitable candidate for broadband fracturing.

[0188] In this embodiment, the oil displacement efficiency, the swept area, and the oil saturation are comprehensively judged and measured. In actual applications, only two or one of them may be used.

[0189] Based on the same inventive concept, the present invention also provides a vertical well lateral broadband fracturing test device, the structure of which is as follows: Figure 14 Shown, including:

[0190] The test data acquisition module 101 is used to obtain experimental data of water drive oil production experiments conducted in a pre-established vertical well conventional fracturing experimental model and a vertical well lateral broadband fracturing experimental model; the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model are manufactured using the vertical well volume fracturing experimental model manufacturing method as described above; wherein the experimental data includes the recorded water output and oil output of the oil production hole, the pressure value obtained at the pressure measurement point, and the resistivity value obtained at the resistivity measurement point.

[0191] The characteristic parameter acquisition module 102 is configured to determine, for each of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model, at least one of the following characteristic parameters based on the experimental data: determining the oil displacement efficiency based on the recorded water yield and oil yield of the oil production hole, determining the pressure sweep range based on the pressure value obtained at the pressure measurement point, and determining the oil saturation based on the resistivity value obtained at the resistivity measurement point;

[0192] The broadband fracturing analysis module 103 is used to determine whether the reservoir to be tested is suitable for broadband fracturing based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

[0193] Based on the same inventive concept, an embodiment of the present invention further provides a vertical well volume fracturing experimental model, which is manufactured using the vertical well volume fracturing experimental model manufacturing method as described above.

[0194] Based on the same inventive concept, an embodiment of the present invention further provides an application of the aforementioned method for preparing a vertical well volume fracturing experimental model in preparing a vertical well volume fracturing experimental model.

[0195] Based on the same inventive concept, an embodiment of the present invention further provides an application of the aforementioned vertical well lateral broadband fracturing test method in vertical well lateral broadband fracturing applicability testing.

[0196] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0197] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0198] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are therefore hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

Claims

1. A method for preparing a vertical well volume fracturing experimental model, characterized in that: include: A vertical well pattern model is produced using a core plate; the vertical well pattern model includes fractures and multiple injection and production holes arranged according to the well pattern form, volume fracturing type and parameters of the oil reservoir to be tested, as well as pressure measurement points and / or resistivity measurement points, wherein the multiple injection and production holes include at least one injection hole for oil displacement test and at least one oil displacement test production hole; The vertical well pattern model is vacuumed, and at least one injection and production hole is selected as a saturated water hole to inject formation water into the model until it reaches a saturated state; Injecting crude oil into the vertical well pattern model in a row-shaped injection and production pattern, with one row of injection and production holes serving as saturated oil injection holes and the other row of injection and production holes serving as saturated oil production holes, until the saturated oil production holes start to discharge only oil instead of water; Injecting crude oil into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are alternately arranged at intervals until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model capable of simulating the formation conditions of the oil reservoir to be tested; The method comprises injecting crude oil into the vertical well pattern model in a cross-injection and production manner in which saturated oil injection holes and saturated oil production holes are arranged alternately and spaced apart until the crude oil in the model reaches a saturated state, thereby obtaining a vertical well volume fracturing experimental model capable of simulating the formation conditions of the oil reservoir to be tested, comprising: According to the arrangement of the injection and production holes in the vertical well pattern model, one of the adjacent injection and production holes is used as a saturated oil injection hole and the other as a saturated oil production hole, the saturated oil injection hole is connected to a displacement pump, and the saturated oil production hole is connected to a meter; Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and formation water is driven to be discharged from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

2. The method for preparing a vertical well volume fracturing experimental model according to claim 1, wherein: The method of using a core plate to make a vertical well pattern model includes: Determine the type and parameters of the fractures to be arranged according to the volume fracturing type and parameters of the reservoir to be tested, and arrange the fractures on the core plate; the volume fracturing type includes conventional fracturing and broadband fracturing; the fracture type includes conventional fracturing fractures and broadband fracturing fractures; Determine the locations of injection and production holes according to the well pattern of the reservoir to be measured and the locations of the selected pressure measurement points, and then arrange the injection and production holes; wherein the injection and production holes arranged at the pressure measurement points are shallow holes, and the injection and production holes at other locations are deep holes; Arranging a pressure measuring device at a pressure measuring point and / or arranging a resistivity measuring device at a resistivity measuring point, installing an injection-production well joint for the injection-production hole, and filling the fracture; The core plate is sealed to obtain a vertical well pattern model.

3. The method for preparing a vertical well volume fracturing experimental model according to claim 2, wherein: The method of determining the type and parameters of fractures to be arranged according to the volume fracturing type and parameters of the reservoir to be tested, and arranging fractures on the core plate includes: According to the volume fracturing type and the number, length and width of the fractures in the reservoir to be tested, the type, number, length and width of the fractures to be arranged are determined according to the scaling rules, and the fractures are arranged on the core plate.

4. The method for preparing a vertical well volume fracturing experimental model according to claim 2, wherein: The method of determining the locations of injection and production holes to be arranged and arranging the injection and production holes according to the well pattern of the oil reservoir to be measured and the locations of the selected pressure measurement points includes: According to the well pattern of the reservoir to be tested, deep holes are drilled in the designated corners and the middle of the cracks of the core plate, and shallow holes are drilled at the pressure measurement points; The deep holes and shallow holes are cleaned and dried to obtain arranged injection and production holes.

5. The method for preparing a vertical well volume fracturing experimental model according to claim 1, wherein: The vertical well pattern model is vacuumed, and at least one injection and production hole is selected as a saturated water hole to inject formation water into the model until it reaches a saturated state, including: Detecting the connectivity of each injection and production hole in the vertical well pattern model; If the connectivity is normal, at least one injection and production hole is reserved as a saturated water hole, at least one injection and production hole is used as a vacuum monitoring point, and the other injection and production holes are used as vacuum points. The vertical well pattern model is vacuumed through the vacuum points. When it is determined that the vacuum degree meets the requirement based on the detection results of the vacuum monitoring points, formation water is injected into the model through the saturated water hole, and the formation water is absorbed by the vertical well pattern model until it reaches a saturated state.

6. The method for preparing a vertical well volume fracturing experimental model according to claim 1, wherein: Injecting crude oil into the vertical well pattern model in a row-type injection and production manner, wherein one row of injection and production holes serves as saturated oil injection holes and the other row of injection and production holes serves as saturated oil production holes, until the saturated oil production holes change from discharging water to discharging only oil, including: The Nth row of injection and production holes in the vertical well pattern model is connected to a displacement pump as a saturated oil injection hole, and the N+1th row of injection and production holes is connected to a meter as a saturated oil production hole, wherein N and N+1 are the serial numbers of two adjacent rows in the vertical well pattern model, and N is an odd number; Crude oil is injected from the saturated oil injection hole and displaced by a displacement pump so that the crude oil is absorbed by the vertical well pattern model and part of the formation water is driven out from the saturated oil production hole until only oil is discharged from the saturated oil production hole.

7. A method for testing lateral broadband fracturing in a vertical well, characterized in that: include: Water drive oil recovery experiments are conducted on a pre-established vertical well conventional fracturing experimental model and a vertical well lateral broadband fracturing experimental model, respectively; the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model are manufactured using the vertical well volume fracturing experimental model manufacturing method according to any one of claims 1 to 6; For the vertical well conventional fracturing test model and the vertical well lateral broadband fracturing test model, at least one of the following characteristic parameters is determined: oil displacement efficiency is determined based on the recorded water yield and oil yield of the oil production hole, pressure sweep range is determined based on the pressure value obtained at the pressure measurement point, and oil saturation is determined based on the resistivity value obtained at the resistivity measurement point; Whether the oil reservoir to be tested is suitable for broadband fracturing is determined based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

8. The method for testing lateral broadband fracturing of a vertical well according to claim 7, wherein: The oil displacement efficiency is determined based on the recorded water yield and oil yield of the oil production hole, including: The water output and oil output of the oil production hole at different times are recorded, and a displacement efficiency comparison chart is drawn based on the water output and oil output at different times to obtain the displacement efficiency at different times.

9. The method for testing lateral broadband fracturing of a vertical well according to claim 7, wherein: The pressure range is determined based on the pressure value obtained at the pressure measurement point, including: The pressure values ​​obtained at each of the pressure measurement points at different times are recorded, and a pressure distribution isobaric map is drawn according to the pressure values ​​of each of the pressure measurement points at different times. The pressure sweep range is obtained according to the pressure distribution isobaric map.

10. The method for testing lateral broadband fracturing of a vertical well according to claim 7, wherein: Determine the oil saturation based on the resistivity values ​​obtained at the resistivity measurement points, including: The resistivity value obtained at each resistivity measurement point is recorded, and the oil saturation at the corresponding point of the model is converted based on the resistivity value obtained at each resistivity measurement point.

11. A vertical well lateral broadband fracturing test device, characterized in that: include: An experimental data acquisition module is used to obtain experimental data of water flooding oil production experiments in a pre-established vertical well conventional fracturing experimental model and a vertical well lateral broadband fracturing experimental model, respectively; the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model are manufactured using the vertical well volume fracturing experimental model manufacturing method according to any one of claims 1 to 6; a characteristic parameter acquisition module for determining, for the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model, at least one of the following characteristic parameters based on the experimental data: determining the oil displacement efficiency based on the recorded water yield and oil yield of the oil production hole, determining the pressure sweep range based on the pressure value obtained at the pressure measurement point, and determining the oil saturation based on the resistivity value obtained at the resistivity measurement point; The broadband fracturing analysis module is used to determine whether the oil reservoir to be tested is suitable for broadband fracturing based on the magnitude of at least one characteristic parameter of the vertical well conventional fracturing experimental model and the vertical well lateral broadband fracturing experimental model.

12. A vertical well volume fracturing experimental model, characterized in that: The vertical well volume fracturing experimental model is prepared using the method for preparing the vertical well volume fracturing experimental model as described in any one of claims 1 to 6.

13. Use of the method for preparing a vertical well volume fracturing experimental model according to any one of claims 1 to 6 in preparing a vertical well volume fracturing experimental model.

14. Use of the vertical well lateral broadband fracturing test method according to any one of claims 7 to 10 in vertical well lateral broadband fracturing applicability testing.

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