Bottom water reservoir water invasion simulation experiment device and method

Abstract

The invention provides a bottom water reservoir water invasion simulation experiment device and method. The device comprises a sand filling model, an oil well, a water tank and a displacement pump. The sand-packed model is used for simulating an oil reservoir by filling a sand body, saturated water and saturated crude oil and obtaining the pressure of the sand-packed model after the crude oil is saturated; the oil well is arranged in the sand filling model; the water tank communicates with the bottom of the sand-packed model and is used for injecting water into the sand-packed model; the displacement pump is communicated with the sand-packed model and is used for saturating crude oil into the sand-packed model; the oil well is used for producing oil from the sand-packed model at set pressure; the mounting position of the water tank is higher than the bottom of the sand-packed model, so that the pressure generated when water descends from the top in the water tank to the bottom of the sand-packed model is equal to the pressure of the sand-packed model saturated with crude oil. The experimental device provided by the invention can simulate the energy change of the bottom water with finite volume multiples in the bottom water coning process.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas reservoir exploitation experiments, and in particular to a device and method for simulating water intrusion in bottom water reservoirs. Background Art

[0002] After an oilfield enters its high-water-cut phase, oil production declines at an accelerated rate. Within these high-water-cut oilfields, bottom-water reservoirs are numerous and possess abundant reserves. Key technologies for developing bottom-water reservoirs are controlling bottom-water coning, maximizing the water-free production period of the wells and ensuring uniform displacement of bottom water to enhance the effectiveness of bottom-water reservoir development. Bottom-water coning refers to the phenomenon whereby, as oil is produced, the reservoir energy decreases, and bottom water gradually flows toward the wells. When this water enters the oil layer, forming two-phase flow, permeability decreases dramatically as water saturation increases, leading to a decline in oil production and significantly impacting reservoir development.

[0003] When simulating the impact of bottom water coning on reservoir development, a high-pressure water pump is typically used to supply water to the bottom of the model at a constant pressure to simulate bottom water at a certain pressure. The impact of bottom water on development outcomes is then studied by observing and analyzing the produced water content of the oil wells and the extent of crude oil recovery within the model. However, using a water pump can only provide bottom water to the reservoir at a constant energy pressure of the initial water body, making it difficult to simulate water bodies of finite size. Summary of the Invention

[0004] In order to simulate the energy change of finite volume multiples of bottom water during the bottom water coning process, this application proposes a bottom water reservoir water invasion simulation experimental device and method, and adopts the following technical solutions:

[0005] In the first aspect, the present application discloses a water invasion simulation experimental device for bottom water reservoirs.

[0006] Based on the above technical solution, the beneficial effects of this application compared with the prior art are as follows:

[0007] The bottom-water reservoir water intrusion simulation experimental device in the present embodiment utilizes a water tank installed at a height higher than the sandfill model. This device utilizes the pressure generated by the falling water body to convert it into the bottom water's own energy, thereby simulating the impact of bottom-water energy on the development of bottom-water reservoirs. On the one hand, using the potential energy of water to increase pressure simulates the trend of gradually decreasing water pressure during water injection, simulating the change in bottom-water energy at a finite volume multiple. On the other hand, by adjusting the water tank's volume by varying its bottom area, the device can simulate the impact of energy changes generated by water bodies of different volume multiples on reservoir oil production, while maintaining the same initial bottom-water pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1This is an overall schematic diagram of the water invasion simulation experimental device for bottom water reservoirs in Example 1 of the present application;

[0009] Figure 2 1 is a flow chart of a water invasion simulation experimental method for a bottom water reservoir in Example 1 of the present application;

[0010] Figure 3 This is a schematic diagram of the structure of the lifting platform in Example 2 of the present application;

[0011] Figure 4 This is a schematic structural diagram of the water tank in Example 3 of the present application;

[0012] Figure 5 This is a connection diagram of the control system in Example 3 of the present application;

[0013] Description of reference numerals:

[0014] 1. Sand filling model; 11. Interlayer; 2. Oil well; 21. Pressure regulating valve; 22. Oil-water separator; 3. Water tank; 31. Fixed side panel; 32. Movable side panel; 33. Bottom panel; 34. Horizontal panel; 35. Cavity; 4. Oil injection valve; 5. Displacement pump; 6. Pressure sensor; 7. Connecting water pipe; 71. Water inlet; 72. Water injection valve; 8. Lifting platform; 9. Driving mechanism; 101. Controller; 102. Display screen. DETAILED DESCRIPTION

[0015] 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.

[0016] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0017] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this disclosure and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on the specific circumstances.

[0019] The inventors discovered that when simulating the impact of bottom water coning on reservoir development, injecting water into the bottom of the model at a constant pressure using a water pump is generally done for the case where the volume of the bottom water is infinite. When the water volume is large enough (generally greater than 50 times), the drop in water energy is negligible under certain conditions, so the bottom water energy can always be represented by a constant initial pressure. However, when the water volume is relatively small, as the bottom water invades the reservoir, the water energy gradually decreases, so the pressure gradually decreases. In this case, it is not possible to simply use a water pump to supply water to simulate the energy change of the water body.

[0020] In order to simulate the energy change of a finite volume multiple of bottom water during the bottom water coning process, the inventors further developed and made the present invention. The present invention is described in detail below through one or more embodiments.

[0021] Example 1

[0022] In the first aspect, the present invention provides a bottom water reservoir water invasion simulation experimental device, referring to Figure 1The device includes a sand filling model 1, an oil well 2, a water tank 3, an oil injection valve 4 and a displacement pump 5; the oil well 2 is arranged in the sand filling model 1; the water tank 3 is connected to the bottom of the sand filling model 1, and the installation position of the water tank 3 is higher than the bottom of the sand filling model 1; the sand filling model 1, the oil injection valve 4 and the displacement pump 5 are connected in sequence; the displacement pump 5 is used to pump crude oil into the sand filling model 1; the sand filling model 1 is used to simulate an oil reservoir by filling sand, saturating water and crude oil; the oil well 2 is used to produce oil from the sand filling model 1 at a set pressure; the water tank 3 is used to inject water into the sand filling model 1, and make the pressure generated by the water body descending from the top of the water tank 3 to the bottom of the sand filling model 1 equal to the pressure after the sand filling model 1 is saturated with crude oil.

[0023] The experimental device in the embodiment of the present application is filled with a certain volume of water in the water tank 3, and the water tank 3 is lifted to a set height. After the water body in the water tank 3 drops to the bottom of the sand filling model 1, the potential energy of the water body itself is converted into kinetic energy, thereby forming the energy in the bottom water. In this process, due to the limited volume of the water tank 3, as the volume of the water body in the water tank 3 decreases, the height of the top of the water body from the bottom of the sand filling model 1 gradually decreases, which reduces the potential energy of the water body itself, and the energy of the water body entering the bottom of the sand filling model 1 also decreases. Therefore, as the water body is continuously injected, the bottom water energy of the sand filling model 1 shows a trend of gradually decreasing, thereby realizing the simulation of the energy change of the bottom water of a limited volume during the bottom water coning process. By analyzing the oil production of the oil well 2, the influence of the water body volume and the corresponding energy on the reservoir development effect is obtained.

[0024] In an optional embodiment, the sandfill model 1 is fabricated as follows: First, a high-pressure-resistant model is prepared. The model is preferably rectangular, with a thickness significantly smaller than its length, width, and height to facilitate observation of the coning process of water coning at the bottom of the reservoir. Fine sand is then filled into the model at a specific permeability. Interlayers 11 may be placed laterally within the sand as needed. Interlayers 11 are composed of a mixture of cement and fine sand with lower permeability. The sand and gravel form a porous medium within the model. This porous medium refers to a solid material containing various interconnected or disconnected cavities or voids, with these cavities distributed randomly or in an ordered geometric pattern. This porous medium is used to simulate the soil layer containing the underground oil reservoir.

[0025] In an alternative embodiment, referring to Figure 1 The outlet of oil well 2 is also connected in sequence to a pressure regulating valve 21 and an oil-water separator 22. Pressure regulating valve 21 is used to adjust the oil production pressure of oil well 2, and oil-water separator 22 is used to separate the oil-water mixture produced by oil well 2. By adjusting pressure regulating valve 21 at the outlet of oil well 2 to produce oil at different pressures, the water content of the oil produced by oil well 2 and the degree of crude oil recovery within the sand pack model 1 are observed and analyzed through oil-water separator 22.

[0026] In an alternative embodiment, referring to Figure 1The sand filling model 1 is also connected to a pressure sensor 6. The pressure sensor 6 is used to monitor the pressure of the crude oil in the sand filling model 1, so that the pressure of the crude oil reaches the simulated reservoir formation pressure when the crude oil is saturated.

[0027] In an alternative embodiment, referring to Figure 1 The volume of water tank 3 is 1-50 times the pore volume of sand-fill model 1, and can be 2, 5, or 10 times. Of course, it can also be a non-integer multiple, such as 1.5 or 2.5 times, to simulate the impact of water bodies of any volume multiple on the oil production of oil well 2. Specifically, the pore volume of sand-fill model 1 is measured using the water saturation method: first, a vacuum pump is used to completely extract the air from the model pores. Then, the sand-fill model 1 is connected to water tank 3. The water in water tank 3 flows into the sand-fill model 1 under a pressure differential until the water in water tank 3 no longer decreases within a set time. By recording the amount of water flowing into the model pores, the pore volume of the sand-fill model 1 is obtained.

[0028] It should be noted that when adjusting the volume multiple, refer to Figure 1 The height of water tanks 3 of varying volumes remains unchanged, while their bottom areas increase exponentially. This ensures that, when water is poured into the sand-filled model 1, the pressure generated by the water descending from the top of the water tanks 3 of varying volumes to the bottom of the sand-filled model 1 remains the same. This means that only the volume multiplication of the water changes, but the initial bottom water pressure remains unchanged. As bottom water continues to intrude, the height of the water tank 3 containing the higher volume multiplication of water decreases less when invading the same volume of bottom water, since the lower area of ​​the water tank 3 containing the higher volume multiplication of water is larger. This results in a smaller drop in energy and pressure for the higher volume multiplication of water.

[0029] In an alternative embodiment, referring to Figure 1 The water tank 3 is connected to the sand-filled model 1 via a connecting water pipe 7. A plurality of water inlets 71 are provided at one end of the connecting water pipe 7, which is close to the sand-filled model 1. The plurality of water inlets 71 are evenly spaced along the length of the bottom of the sand-filled model 1. Furthermore, to control the water injection process, each water inlet 71 is provided with a water injection valve 72.

[0030] Secondly, refer to Figure 2 The present application also discloses a bottom water reservoir water invasion simulation experimental method, which is applied to the above-mentioned bottom water reservoir water invasion simulation experimental device, and the method comprises:

[0031] S1: Making a sand-filled model 1.

[0032] S2: Calculate the pore volume of the sandfill model 1 after saturation with water. After calculating the pore volume of the sandfill model 1 after saturation with water using the water saturation method, further calculate the porosity. Porosity is the ratio of the pore volume to the volume of the entire sandfill model 1.

[0033] S3: Saturate the sand pack 1 with crude oil using displacement pump 5 until the pressure of the crude oil in the sand pack 1 reaches the pressure of the formation in which the simulated oil reservoir is located. Specifically, during the process of pumping crude oil, the pressure change of the crude oil is monitored by pressure sensor 6. When the crude oil is fully saturated and reaches the set pressure, the saturation is stopped.

[0034] S4: Lift the water tank 3 to a set height and then fill it with water so that the pressure generated by the water flowing from the top of the water tank 3 to the bottom of the sand filling model 1 is equal to the pressure after the sand filling model 1 is saturated with crude oil. Specifically, the set height of the water tank 3 should be calculated according to the following formula:

[0035] ρg(H+h)=P;

[0036] Where ρ is the water density; g is the acceleration due to gravity; H is the height of the bottom of water tank 3 from the bottom of sand-filled model 1; h is the height of water tank 3; and P is the pressure after sand-filled model 1 is saturated with crude oil. It should be noted that during actual filling, water tank 3 should be filled so that the top of the water is flush with the top of water tank 3.

[0037] S5: Oil well 2 is set to produce oil at a set pressure. Specifically, the set pressure is adjusted by pressure regulating valve 21. During the oil production process, some bottom water will enter the oil layer, and crude oil will be automatically discharged under the energy of the water. During this period, the crude oil pressure will continue to decrease as the crude oil is discharged. Once the pressure drops from the initial simulated formation pressure to a certain pressure value, the experiment is terminated. The produced oil-water mixture is further separated by oil-water separator 22, and data such as the water content of the produced crude oil and the crude oil recovery volume can be obtained.

[0038] S6: The bottom area of ​​the water tank is changed, and the above bottom water reservoir water invasion simulation experiment process is repeated. Specifically, the experiment can be repeated multiple times, and each experiment only changes the bottom area of ​​the water tank 3. The volume of the water tank 3 after each adjustment is 1-50 times the pore volume of the sand packing model 1.

[0039] In summary, the experimental device for simulating water intrusion in bottom-water reservoirs in the present embodiment utilizes a water tank 3 installed at a height higher than the sandfill model 1. This device utilizes the pressure generated by the falling water body to convert it into the energy of the bottom water itself, thereby simulating the impact of bottom-water energy on the development of bottom-water reservoirs. On the one hand, utilizing the potential energy of water for pressurization can simulate the trend of gradually decreasing water pressure during the water injection process, thereby simulating the change in bottom-water energy at a finite volume multiple. On the other hand, the installation of a water tank 3 with exponentially increasing bottom area can simulate the impact of energy changes generated by water bodies of different volume multiples on reservoir oil production, while maintaining the same initial bottom-water pressure.

[0040] Example 2

[0041] The difference between this embodiment and embodiment 1 is that, referring to Figure 3 To further improve the lifting process of the water tank 3, the apparatus in this embodiment further includes a lifting platform 8, on which the water tank 3 is mounted. Specifically, the water tank 3 can be detachably mounted on the lifting platform 8 by bolts or the like. The lifting platform 8 is used to raise the water tank 3 to a set height so that the pressure generated by the water dropping from the set height to the bottom of the sand filling model 1 is equal to the pressure after the sand filling model 1 is saturated with crude oil.

[0042] Specifically, the lifting platform 8 can be implemented by any existing technology such as a motor screw or a cylinder, and the lifting height can be controlled by any method such as a ruler, a sensor, etc.

[0043] Example 3

[0044] This embodiment is further improved on the basis of embodiment 2. Figure 4 In this embodiment, the water tank 3 is open at the top, and includes a fixed side panel 31 and a movable side panel 32 that are arranged opposite to each other, as well as other panels connected to the fixed side panel 31 and the movable side panel 32. It should be noted that the other panels specifically include a bottom panel 33 and a horizontal panel 34 that is perpendicular to the fixed side panel 31 and the movable side panel 32. The fixed side panel 31, the movable side panel 32 and the other panels form a cavity 35 for accommodating water. Among them, the side edge of the fixed side panel 31 is fixedly and sealedly connected to the other panels of the water tank 3, and the side edge of the movable side panel 32 is dynamically and sealedly connected to the other panels of the water tank 3.

[0045] Further, refer to Figure 4 The fixed side panels 31 and other panels can be integrally formed to form the four sides of the tank body. The movable side panels 32 are opposite the fixed side panels 31. The two sides of the movable side panels 32 are dynamically sealed to the corresponding transverse panels 34, and the bottom edges are dynamically sealed to the bottom panel 33. In other words, each movable side panel 32 can move along the length of the transverse panels 34 to change the bottom area of ​​the water tank 3 and thus the volume of the cavity 35.

[0046] It should be noted that sufficient sealing should be ensured between the movable side panel 32 and the transverse panel 34 and the bottom panel 33. The sliding sealing between the movable side panel 32 and the adjacent panels can be achieved by using sealing strips and waterproof seals in combination.

[0047] Further, refer to Figure 4 The movable side plate 32 is further connected to a driving mechanism 9, which is used to drive the movable side plate 32 to move toward or away from the fixed side plate 31, so as to increase or decrease the volume of the cavity 35 exponentially. Specifically, the driving mechanism 9 can be any one of a cylinder, a motor screw, etc.

[0048] Furthermore, in order to realize intelligent control of the entire experimental process, refer to Figure 5The experimental apparatus also includes a control system, comprising a controller 101 and a display screen 102, which are interconnected. The controller 101 is respectively connected to the drive mechanism 9, the lifting platform 8, the pressure sensor 6, and the pressure regulating valve 21. In response to the water volume multiple value, the pore volume value of the sand filling model 1, and the known height of the water tank 3 input by the user via the display screen 102, the controller 101 calculates the bottom area of ​​the water tank 3, thereby controlling the drive mechanism 9 and adjusting the movement distance of the movable side plate 32. The controller 101 also calculates the lifting height based on the pressure value of the sand filling model 1 after saturation with crude oil, obtained by the pressure sensor 6, and the known height of the water tank 3, thereby controlling the lifting platform 8 to adjust the lifting height. Furthermore, during the simulated crude oil production process, the controller 101 can also obtain real-time pressure changes in the crude oil within the sand filling model 1, providing reference data for pressure changes in actual reservoir production. Furthermore, the controller 101 can adjust the pressure of the pressure regulating valve 21 based on the oil production pressure value input by the user.

[0049] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, apparatus, or computer program products. Thus, embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0050] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it will be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, to the extent that the term "comprising" is used in the specification or claims, the term is intended to be encompassed in a manner similar to the term "including", as explained by the use of "including" as a transitional word in the claims. In addition, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".

Claims

1. A water invasion simulation experimental device for bottom water reservoirs, characterized in that: Includes sand pack model, oil well, water tank and displacement pump; The sand filling model is used to simulate an oil reservoir by filling sand bodies, saturating water and saturating crude oil, and obtaining the pressure of the sand filling model after saturation with crude oil; The oil wells are arranged in the sand filling model; The water tank is in communication with the bottom of the sand-filled model and is used to inject water into the sand-filled model; The displacement pump is in communication with the sand filling model and is used to saturate the sand filling model with crude oil; The oil well is used to produce oil at a set pressure from within the sand pack model; The water tank is installed at a position higher than the bottom of the sand-filled model, so that the pressure generated by water dropping from the top of the water tank to the bottom of the sand-filled model is equal to the pressure of the sand-filled model after it is saturated with crude oil.

2. The device according to claim 1, characterized in that The volume of the water tank is 1-50 times the pore volume of the sand filling model after being saturated with water.

3. The device according to claim 1, characterized in that The device also includes a lifting platform; The water tank is arranged on the lifting platform; The lifting platform is used to raise the water tank to a set height so that the pressure generated by the water body dropping from the set height to the bottom of the sand filling model is equal to the pressure of the sand filling model after being saturated with crude oil.

4. The device according to claim 1 or 2, characterized in that The water tank includes a fixed side plate and a movable side plate arranged opposite to each other; The fixed side panels, the movable side panels and other panels enclose a cavity for containing water; The side edges of the fixed side panels are fixedly and sealedly connected to the other panels of the water tank; The side edges of the movable side panels are dynamically sealed with the other panels of the water tank; The movable side plate can move toward or away from the fixed side plate to increase or decrease the volume of the cavity exponentially.

5. The device according to claim 4, characterized in that The device also includes a driving mechanism; The driving mechanism is used to drive the movable side plate to move toward or away from the fixed side plate.

6. The device according to claim 4, characterized in that The water tank is connected to the sand-filled model via a connecting water pipe; The connecting water pipe is provided with a plurality of water inlets at one end close to the sand-filled model; Each water inlet is provided with a water injection valve.

7. The device according to claim 1, characterized in that The device also includes a pressure sensor; The pressure sensor is connected to the sand filling model and is used to monitor the pressure of the crude oil in the sand filling model.

8. The device according to claim 1, characterized in that The device includes a pressure regulating valve and an oil-water separator; The oil well, pressure regulating valve and oil-water separator are connected in sequence; The pressure regulating valve is used to adjust the oil production pressure of the oil well; The oil-water separator is used to separate the oil-water mixture produced by the oil well.

9. A water invasion simulation experimental method for bottom water reservoirs, characterized in that: The method is applied to the bottom water reservoir water invasion simulation experimental device according to any one of claims 1 to 8, and the method comprises: Saturate the sandfill model with water; Calculate the pore volume of the sandfill model after saturation with water; Saturating the sand filling model with crude oil by a displacement pump so that the pressure of the sand filling model after saturation with crude oil reaches the reservoir formation pressure; After the water tank is lifted to a set height, water is poured into the sand-filled model so that the pressure generated by the water falling from the top of the water tank to the bottom of the sand-filled model is equal to the pressure of the sand-filled model after it is saturated with crude oil; The oil well is put into production at a set pressure; The bottom area of ​​the water tank was changed and the above bottom water reservoir water invasion simulation experiment process was repeated.

10. The method according to claim 9, characterized in that The method of raising the water tank to a set height and then filling the water tank with water so that the pressure generated by the water falling from the top of the water tank to the bottom of the sand filling model is equal to the pressure of the sand filling model after being saturated with crude oil includes: The set height is calculated according to the following formula: ρg(H+h)=P; Where ρ is the water density; H is the height from the bottom of the water tank to the bottom of the sand filling model; h is the height of the water tank; and P is the pressure after the sand filling model is saturated with crude oil.

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