Visual experiment device and method for evaluating screen pipe gravel filling sand prevention technology

Abstract

The invention discloses a visual experiment device and method for evaluating a screen pipe gravel filling sand prevention technology, and belongs to the technical field of oil and gas exploitation. The upper portion of the inner side of the visual model box is in sliding fit with a top screen in the vertical direction, and a loading part is arranged at the top of the visual model box. A bottom screen is arranged at the lower part of the inner side of the visual model box; a filtering simulation space for placing gravels is formed in the inner space of the visual model box between the top screen and the bottom screen; the visual model box is connected with the injection system; and a sand collecting pipe is arranged at the lower part of the bottom screen in the visual model box. The device can simulate the sand production condition when the gravity direction of the sand in the bottom hole stratum is the same as the flowing direction of the fluid and the invasion process of the stratum sand to the gravel layer, and can be used for evaluating and determining the optimal particle size range of the sand prevention gravel; and a research experiment for evaluating the filling sand prevention effect of the selected gravel particle size range under various variables such as production flow rate and sand-carrying concentration can also be carried out.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a visual experimental device and method for evaluating gravel-filled sand control technology in screen tubes. Background Technology

[0002] Most oil wells are prone to sand production, which can lead to significant economic losses. The production and geological parameters of each sand-producing well vary, so appropriate sand control measures need to be selected based on the specific sand production situation.

[0003] Among them, the gravel-filled screen method for sand control is widely used in oilfield sand control due to its good sand control effect, strong adaptability, simple operation, and low cost. Currently, considering the improvement of single-well utilization or the development of well networks, drilling types are increasingly moving towards horizontal wells. When carrying out sand control during horizontal well production, such as... Figure 1 As shown, formation sand 03 is blocked from entering the wellbore by filling a gravel layer between the wellbore screen 01 and the well wall 02. The specific operation process is as follows: the wellbore screen 01 is run into the producing section, forming an annular space between it and the well wall 02; gravel with optimized particle size is pumped into the annular space using a high-pressure pump; the gravel forms a multi-layer filter structure between the formation sand 03 and the wellbore screen 01, allowing oil and gas to pass through while blocking the formation sand 03. Among them, the migration capacity of formation sand is related to the gravity direction 04 of sand particles and the fluid flow direction 05. When the two directions coincide, the migration capacity of sand particles is the strongest, and the reservoir sand production is the easiest and most severe.

[0004] Before applying the screen-tube gravel-filled sand control method to horizontal well sand control, it is necessary to conduct sand control effect experiments to evaluate the working conditions in which sand production is most likely to occur in the reservoir, in order to select a suitable gravel particle size range.

[0005] However, existing experimental devices generally do not simulate the sand discharge situation when the gravity direction of the sand particles is the same as the fluid flow direction, and their visualization level is low, which greatly hinders operators from determining the particle size range of the sand control gravel.

[0006] Based on this, this application proposes a visual experimental device and method for evaluating gravel-filled sand control technology in screen pipes. It can simulate the sand production situation when the gravity direction of sand particles and the fluid flow direction are the same in the well bottom. It can be used to evaluate and determine the optimal particle size range of sand control gravel based on the target formation sand particle size, fluid viscosity, production flow rate, and sand carrying concentration. It can also be used to conduct research experiments to evaluate the sand control effect of the selected gravel particle size range under multiple variables such as production flow rate and sand carrying concentration. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a visual experimental device for evaluating gravel-filled sand control technology in sieve tubes.

[0008] To achieve the above object, the present application adopts the following technical scheme: The visualized experimental device for evaluating sand control screen gravel packing technology comprises a visualized model box. A top screen for dispersing the sand-carrying fluid is slidably fitted on the inner upper portion of the visualized model box in the vertical direction, and a loading portion for simulating the reservoir overburden pressure is arranged on the top of the visualized model box and connected with the top screen. A bottom screen for simulating the wellbore screen is arranged on the inner lower portion of the visualized model box. The internal space of the visualized model box between the top screen and the bottom screen forms a filtration simulation space for placing the gravel. The visualized model box is connected with an injection system for injecting the sand-carrying fluid into the filtration simulation space. A sand collecting pipe for collecting the sand particles is arranged on the lower portion of the bottom screen in the visualized model box. A plurality of pressure transmitters for measuring the pressure at different positions in the filtration simulation space are uniformly arranged on the visualized model box in the vertical direction.

[0009] Preferably, the visualized model box comprises a main cylinder in a cylindrical structure, a top cover arranged on the top end of the main cylinder, and a bottom plate arranged on the bottom end of the main cylinder. A plurality of annular grooves are arranged on the inner wall of the main cylinder in the axial direction, and the central axis of the annular grooves is consistent with the central axis of the main cylinder.

[0010] Preferably, the main cylinder comprises an upper sand cylinder and a lower sand cylinder coaxially connected, and the lower sand cylinder comprises a plurality of cylindrical structures coaxially connected. The top cover is arranged on the top end of the upper sand cylinder, the radially outer end of the bottom screen is coaxially fixedly arranged with an upwardly extending lower mounting ring, the lower end of the lower sand cylinder is clamped in the lower mounting ring, and the bottom plate is arranged on the bottom end of the bottom screen. A clamping mechanism for clamping and fixing the top cover, the upper sand cylinder, the lower sand cylinder, the bottom screen and the bottom plate is arranged between the top cover and the bottom plate.

[0011] Preferably, the main cylinder is nested and fitted through the clamping mechanism between the adjacent two cylindrical structures. The clamping mechanism comprises an upper annular clamping groove on the inner side of the bottom end of the upper cylindrical structure and a lower annular clamping groove on the outer side of the bottom end of the lower cylindrical structure, the upper annular clamping groove forms an upper annular clamping block corresponding to the bottom end of the upper cylindrical structure, and the lower annular clamping groove forms a lower annular clamping block corresponding to the top end of the lower cylindrical structure. The upper annular clamping block is matched in the lower annular clamping groove, the lower annular clamping block is matched in the upper annular clamping groove, and the first annular sealing piece is arranged between the bottom end of the upper annular clamping block and the bottom end of the lower annular clamping groove.

[0012] Preferably, the bottom end of the top cover is provided with a top cover clasp capable of being clamped into the upper sand cylinder, and a second annular sealing piece is arranged between the top end of the upper sand cylinder and the top cover. The third annular sealing piece is arranged between the bottom screen and the lower sand cylinder and between the bottom screen and the bottom plate.

[0013] Preferably, the clamping mechanism comprises three clamping screws distributed in the circumferential direction, the bottom plate is provided with a first countersunk hole for the clamping screw to pass upward, and the top cover is provided with a first connecting hole for the clamping screw to pass upward. After the clamping screw passes through the corresponding first countersunk hole and the first connecting hole upward, the clamping nut is screwed on the clamping screw at the upper part of the first connecting hole, and the clamping nuts on all clamping screws are tightened to realize the clamping and sealing of the top cover, the upper sand cylinder, the lower sand cylinder, the bottom screen and the bottom plate.

[0014] Preferably, the bottom plate is provided with a tapered hole in communication with the sand collecting pipe, the large end of the tapered hole faces the bottom screen, and the small end of the tapered hole faces the sand collecting pipe.

[0015] Preferably, the loading part comprises a gas cylinder fixedly arranged on the outside of the top of the visualization model box, and the piston rod of the gas cylinder is connected with the upper pressing plate after penetrating into the inside of the visualization model box downward. The outer side wall of the upper pressing plate is provided with an annular mounting groove at the upper part, the first sealing ring is arranged in the annular mounting groove, and the bottom end of the upper pressing plate is coaxially provided with an upper pressing ring. The top end of the upper mounting ring is coaxially fixedly provided with an upper mounting ring, and the inner side wall of the upper mounting ring is threadedly connected with the outer side wall of the upper pressing ring. The second sealing ring is arranged between the top end of the upper mounting ring and the upper pressing plate.

[0016] The application also provides a visualization experiment method for evaluating the screen gravel packing sand prevention technology.

[0017] The visualization experiment method for evaluating the screen gravel packing sand prevention technology is implemented based on the visualization experiment device for evaluating the screen gravel packing sand prevention technology, and comprises the following steps. Step 1, preparation of gravel and experimental formation sand; The experimental formation sand is the corresponding formation sand of the reservoir or is prepared; when being prepared, the experimental formation sand is prepared by screening fine sand and mixing in proportion according to the particle size mass distribution curve of the target formation sand; Prepare N1 groups of experimental gravels with different particle size ranges; Step 2, select the optimal experimental gravel particle size range based on the fluid viscosity, sand-carrying concentration and production flow rate of the target formation, as follows: Step 21, preparation of sand-carrying fluid; Determine the experimental fluid, and the viscosity of the experimental fluid is consistent with the fluid viscosity of the target formation; mix the experimental fluid with the experimental formation sand to form the sand-carrying fluid according to the sand-carrying concentration of the target formation; Step 22, let i = 1, i represents the particle size range number of the experimental gravel, and the smaller i is, the smaller the median in the corresponding particle size range is; Step 23, clean the visualization model box and detect the sealing performance; Step 24, prepare the filling layer; Place the experimental gravel in the i-th particle size range in the visualization model box, and drive the top screen to compact the experimental gravel layer through the loading part; Step 25, injection of sand-carrying fluid; Set a collection barrel at the bottom of the sand collection pipe, start the injection system, and inject the sand-carrying fluid from the upper part of the visualization model box into the experimental gravel layer in the filtration simulation space until the required experimental time is reached, wherein the injection flow rate of the sand-carrying fluid is consistent with the production flow rate of the target formation; During the process, the migration and deposition of sand particles in the experimental gravel layer in the visualization model box are photographed by a camera; and the pressure data are collected by a pressure transmitter; Step 26, sand production amount statistics; After filtering and drying, the experimental formation sand collected in the collection barrel is weighed to obtain the sand production mass corresponding to the i-th particle size range experimental gravel; Step 27, when i < N1, let i = i + 1, and enter step 23; Otherwise, enter step 28; Step 28, determine the optimal experimental gravel particle size range based on the fluid viscosity, sand-carrying concentration and production flow rate of the target formation based on the comprehensive judgment method of sand blocking and fluid flow capacity; Step 3, considering the differences in production flow rate and sand-carrying concentration before and after production, prepare sand-carrying fluids with different sand-carrying concentrations according to the actual production situation, select different injection flow rates within the production range, and further evaluate the gravel in the optimal particle size range determined in step 2 for sand control under different sand-carrying concentrations and injection flow rates; as follows: Step 31, the combination of sand-carrying concentration and injection flow rate forms a variable combination, the specific value of each variable in the variable combination in each experiment is determined as the experimental input data, and each set of experimental input data is numbered, wherein the total number of experimental input data is N2; Step 32, let j = 1, j represents the serial number of experimental input data; Step 33, clean the visualization model box and perform a sealing test; Step 34, prepare the packing layer; Place the optimal particle size range experimental gravel in the visualization model box, and drive the top screen to compact the experimental gravel layer through the loading part; Step 35, injection of sand-carrying fluid; Set a collection barrel at the bottom of the sand collection pipe, start the injection system, and inject the sand-carrying fluid with the sand-carrying concentration value corresponding to the serial number j into the experimental gravel layer in the filtration simulation space from the upper part of the visualization model box until the required experimental time is reached, wherein the injection flow rate is the injection flow rate value corresponding to the serial number j; During the process, the migration and deposition of sand particles in the experimental gravel layer in the visualization model box are captured by a camera; pressure data are collected by a pressure transmitter; Step 36, sand production volume statistics; After filtering and drying, the experimental formation sand collected in the collection barrel is weighed to obtain the sand production mass corresponding to the jth experimental input data; Step 37, when j < N2, let j = j + 1, and enter step 33; Otherwise, enter step 38; Step 38, based on the comprehensive judgment method of sand blocking and fluid flow capacity, the sand control performance of the optimal particle size range gravel under different sand-carrying concentrations and injection flow rates is evaluated.

[0018] Preferably, based on the comprehensive judgment method of sand blocking and fluid flow capacity, the specific method is as follows: Construct sand control parameters The calculation formula is: Formula (1) Formula (2) Formula (3) Formula (4) Wherein, is the sand production rate; is the sand production mass; is the total mass of injected sand; is the injection flow rate; is the cross-sectional area of the filtration simulation space; is the experimental time; is the sand-carrying concentration of the sand-carrying fluid; is the permeability; is the absolute value of the pressure difference detected by the uppermost and lowermost pressure transmitters at the end of the experiment; is the viscosity of the experimental fluid; is the vertical distance between the uppermost and lowermost pressure transmitters; In the step 28, the values of the sand control parameters of each experiment are calculated, and the experimental gravel particle size range corresponding to the sand control parameter value of the smallest is taken as the optimal particle size range based on the fluid viscosity, sand-carrying concentration and production flow rate of the target formation; In the step 38, the values of the sand control parameters of each experiment are calculated, and the sand control performance of the optimal particle size range gravel under different sand-carrying concentrations and injection flow rates is evaluated using the values of the sand control parameters , and the smaller the value of the sand control parameter , the better the sand control performance.

[0019] The beneficial effects of the present application are: (1) The present application can simulate the sand production condition when the gravity direction of the formation sand particles and the fluid flow direction are the same and the invasion process of the formation sand to the gravel layer, and can be used for the evaluation and determination of the optimal particle size range of the sand control gravel based on the target formation sand particle size, fluid viscosity, production flow rate and sand-carrying concentration. The research experiment on the filling sand control effect evaluation of the selected gravel particle size range under multiple variables of the production flow rate and sand-carrying concentration can also be carried out.

[0020] (2) In the present application, the annular groove is arranged to overcome the phenomenon of "inner wall bypassing" of the sand particles, effectively avoid the influence of the fluid flowing along the cylinder wall on the sand particle migration, and significantly improve the accuracy and reliability of the experimental data.

[0021] (3) In the present application, the visual model box adopts multiple cylinders which are nested and assembled through the clamping structure, facilitating installation and disassembly.

[0022] (4) In the present application, the annular groove is formed at the connection of each cylinder structure of the main cylinder, avoiding the boring tool process on the inner wall of the main cylinder, reducing the workload while ensuring the strength of the main cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of the present application form a part of the present application and serve to provide further understanding of the present application, the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application.

[0024] Figure 1 is a sand control schematic diagram in the production process of a horizontal well; Figure 2 is the connection diagram of the visualization experimental device for evaluating screen gravel packing sand prevention technology of the present application; Figure 3 is the structural diagram of the visualization model box in the present application; Figure 4 is the structural diagram of the visualization model box in the present application; Figure 5 is the structural diagram of the snap mechanism in the present application; Figure 6 is the cooperation diagram of the upper pressing plate and the top screen in the present application; wherein: 01, wellbore screen pipe; 02, well wall; 03, formation sand; 04, sand grain gravity direction; 05, fluid flow direction; 1, visualization model box; 11, sand feeding cylinder; 12, cylindrical body; 13, top cover; 131, top cover snap ring; 132, second annular sealing piece; 14, bottom plate; 141, conical hole; 15, upper annular clamping groove; 151, upper annular clamping block; 16, lower annular clamping groove; 161, lower annular clamping block; 17, first annular sealing piece; 18, clamping screw; 181, clamping nut; 19, base; 191, supporting screw; 192, supporting nut; 2, top screen; 21, upper mounting ring; 22, second sealing ring; 3, loading part; 31, air cylinder; 32, two-position five-way valve; 33, pressure gauge; 34, pressure regulator; 35, air compressor; 36, upper pressing plate; 361, first sealing ring; 362, upper pressing ring; 4, bottom screen; 41, lower mounting ring; 42, third annular sealing piece; 5, filtration simulation space; 51, annular groove; 6, injection system; 61, medium tank; 62, mud pump; 63, injection pipeline; 64, injection valve; 7, sand collecting pipe; 8, pressure transmitter; 81, display screen. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in order to provide a further understanding of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0026] It is also important to note that the terms used herein are not intended to limit the particular embodiments of the present application to the preferred embodiments described. Rather, the terms are used only to describe specific embodiments of the present application. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well, i.e., the inclusion of "a" or "an" or "the" means "one or more" unless the context clearly indicates otherwise. Furthermore, it is to be understood that the use of the term "including," "including," "includes," "has," "have," "has," "having," or "comprising" to describe a feature, step, operation, component, element, or the like, means "one or more, but not necessarily all" of those elements or features that are so described.

[0027] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0028] In this invention, terms such as "connected" and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Example 1: like Figures 2-6 As shown, the visualization experimental device for evaluating the gravel-filled sand control technology of sieve tubes includes a visualization model box 1, which is made of high-strength transparent acrylic glass to achieve full visualization. The upper inner side of the visualization model box 1 is fitted with a top screen 2 for dispersing sand-carrying fluid, which slides vertically. The top of the visualization model box 1 is provided with a loading part 3 connected to the top screen 2 to simulate reservoir overburden pressure. The lower inner side of the visualization model box 1 is provided with a bottom screen 4 for simulating the well shaft screen 01; The internal space of the visualization model box 1 between the top screen 2 and the bottom screen 4 forms a filtration simulation space 5 for placing gravel; The visualization model box 1 is connected to the injection system 6 used to inject sand-carrying fluid into the filtration simulation space 5; The bottom of the bottom screen 4 in the visualization model box 1 is equipped with a sand collection pipe 7 for collecting sand particles. The visualization model box 1 is uniformly equipped with several pressure transmitters 8 along the vertical direction for measuring the pressure at different locations within the filter simulation space 5. The real-time monitoring data of the pressure transmitters 8 can be displayed on the computer screen 81.

[0031] Preferably, the visualization model box 1 includes a main cylinder with a cylindrical structure, a top cover 13 is provided at the top of the main cylinder, and a bottom plate 14 is provided at the bottom of the main cylinder; The inner wall of the main cylinder corresponding to the filter simulation space 5 is provided with several annular grooves 51 arranged axially, and the central axis of the annular grooves 51 is consistent with the central axis of the main cylinder.

[0032] The setting of the annular grooves 51 in the application overcomes the phenomenon of sand particles "circling the inner wall", effectively avoids the influence of fluid flow along the cylinder wall on sand particle migration, and significantly improves the accuracy and reliability of experimental data. Circling the inner wall refers to the phenomenon that fluid will flow downstream along the smooth inner wall of the visualization model box 1 based on the law of least resistance. When the device in the application is used for experiments, the interior of the visualization model box 1 is filled with gravel layers, which hinders the movement of fluid, and there are large pores between the gravel and the inner wall of the visualization model box 1, so the fluid tends to flow along the inner wall, which will weaken the displacement effect of the experimental formation sand and affect the experimental results. In order to avoid this phenomenon, the annular grooves 51 are arranged in the interior of the visualization model box 1 in the application, so that the gravel will be embedded in the annular grooves 51, which can effectively avoid the influence of fluid flow along the cylinder wall on sand particle migration, and significantly improve the accuracy and reliability of experimental data.

[0033] Preferably, the main cylinder body includes an upper sand cylinder 11 and a lower sand cylinder coaxially connected, and the lower sand cylinder includes a plurality of cylindrical bodies 12 coaxially connected; The top cover 13 is arranged at the top end of the upper sand cylinder 11, the radially outer end of the bottom screen 4 is fixedly arranged with an upwardly extending lower mounting ring 41, the lower end of the lower sand cylinder is clamped into the lower mounting ring 41, and the bottom plate 14 is arranged at the bottom end of the bottom screen 4; Specifically, the bottom plate 14 is provided with a circular sunken hole matched with the lower mounting ring 41 and the bottom screen 4. The clamping mechanism is arranged between the top cover 13 and the bottom plate 14 to clamp and fix the top cover 13, the upper sand cylinder 11, the lower sand cylinder, the bottom screen 4 and the bottom plate 14.

[0034] Preferably, the main cylinder body includes an upper sand cylinder 11 and a lower sand cylinder coaxially connected, and the lower sand cylinder includes a plurality of cylindrical bodies 12 coaxially connected; The clamping mechanism includes an upper annular clamping groove 15 arranged on the inner side of the bottom end of the upper cylinder structure and a lower annular clamping groove 16 arranged on the outer side of the bottom end of the lower cylinder structure, the upper annular clamping groove 15 forms an upper annular clamping block 151 at the bottom end of the corresponding upper cylinder structure, and the lower annular clamping groove 16 forms a lower annular clamping block 161 at the top end of the corresponding lower cylinder structure. In the clamping mechanism, the upper annular clamping block 151 is matched in the lower annular clamping groove 16, the lower annular clamping block 161 is matched in the upper annular clamping groove 15, and a first annular sealing piece 17 is arranged between the bottom end of the upper annular clamping block 151 and the bottom end of the lower annular clamping groove 16; when the upper annular clamping block 151 is pressed on the corresponding first annular sealing piece 17, an annular groove 51 is formed between the top end of the upper annular clamping groove 15 and the top end of the lower annular clamping block 161.

[0035] In the application, annular grooves 51 are formed at the connection of each cylinder structure constituting the main cylinder, avoiding boring cutter process on the inner wall of the main cylinder, reducing the workload while ensuring the strength of the main cylinder.

[0036] Preferably, the bottom end of the top cover 13 is provided with a top cover snap ring 131 capable of being clamped into the top sand cylinder 11, and a second annular sealing sheet 132 is arranged between the top end of the top sand cylinder 11 and the top cover 13. A third annular sealing sheet 42 is arranged between the bottom screen 4 and the lower sand cylinder and between the bottom screen 4 and the bottom plate 14.

[0037] Preferably, the clamping mechanism includes three clamping screws 18 distributed in the circumferential direction, the bottom plate 14 is provided with first countersunk holes for the clamping screws 18 to pass upward, and the top cover 13 is provided with first connecting holes for the clamping screws 18 to pass upward. After the clamping screws 18 pass upward through the corresponding first countersunk holes and first connecting holes, clamping nuts 181 are screwed on the clamping screws 18 at the upper part of the first connecting holes, and all clamping nuts 181 on the clamping screws 18 are tightened to realize clamping and sealing of the top cover 13, the top sand cylinder 11, the lower sand cylinder, the bottom screen 4, and the bottom plate 14.

[0038] Preferably, the bottom plate 14 is provided with a tapered hole 141 communicating with the sand collecting pipe 7, the large end of the tapered hole 141 faces the bottom screen 4, and the small end of the tapered hole 141 faces the sand collecting pipe 7.

[0039] The included angle between the generatrix of the wall surface of the tapered hole 141 and the central axis is 65°-70°.

[0040] Specifically, the bottom of the visualization model box 1 is provided with a base 19, and the base 19 and the bottom plate 14 are connected through three support screws 191 distributed in the circumferential direction. The base 19 is provided with second countersunk holes for the support screws 191 to pass upward, and the bottom plate 14 is provided with second connecting holes for the support screws 191 to pass upward. After the support screws 191 pass upward through the corresponding second countersunk holes, first support nuts 192 are screwed, and after the support screws 191 pass upward through the corresponding second connecting holes, second support nuts 192 are screwed, and all support nuts 192 on the support screws 191 are tightened to keep the bottom plate 14 horizontal, realizing support of the visualization model box 1.

[0041] Preferably, the loading part 3 includes a cylinder 31 fixedly disposed on the outer side of the top of the visualization model box 1. The piston rod of the cylinder 31 passes downward into the interior of the visualization model box 1 and is connected to the upper pressure plate 36. Specifically, the piston rod of the cylinder 31 passes downward through the top cover 13 and is connected to the upper pressure plate 36 inside the visualization model box 1. An annular mounting groove is provided on the upper part of the outer side wall of the upper pressure plate 36. A first sealing ring 361 is provided in the annular mounting groove. The first sealing ring 361 is used to realize the axial sealing sliding fit between the upper pressure plate 36 and the inner wall of the visualization model box 1. An upper pressure ring 362 is coaxially provided at the bottom end of the upper pressure plate 36. The top of the top screen 2 is coaxially fixed with an upper mounting ring 21, and the inner side wall of the upper mounting ring 21 is threadedly connected to the outer side wall of the upper pressure ring 362. A second sealing ring 22 is provided between the top end of the upper mounting ring 21 and the upper pressure plate 36. The second sealing ring 22 is used to achieve axial sealing sliding fit between the top screen 2 and the inner wall of the visualization model box 1.

[0042] Specifically, the rod chamber and rodless chamber in the cylinder 31 are connected to two ports of the two-position five-way valve 32, and the other port of the two-position five-way valve 32 is connected in sequence to the pressure gauge 33, the pressure regulator 34, and the air compressor 35.

[0043] Preferably, the injection system 6 includes a medium tank 61 for holding the sand-carrying fluid, and the medium tank 61 is equipped with a stirrer to ensure the uniformity of mixing. The outlet of the medium tank 61 is connected to the inlet of the mud pump 62, and the outlet of the mud pump 62 is connected to an injection pipeline 63, which passes through the top cover 13 from top to bottom. An injection valve 64 is provided on the injection pipeline 63.

[0044] Example 2: A visual experimental method for evaluating gravel-filled sand control technology for sieve tubes is implemented based on a visual experimental apparatus for evaluating this technology, and includes the following steps: Step 1, Preparation of gravel and experimental formation sand; The experimental formation sand was prepared using formation sand 03 from the corresponding reservoir or by mixing. When preparing the sand, the fine sand was screened and then mixed according to the particle size distribution curve of the formation sand 03 of the target formation. Prepare experimental gravel of different particle size ranges in group N1; the particle size range of the experimental gravel was determined as follows: When uniformity coefficient At that time, the minimum particle size of the experimental gravel for Maximum particle size of experimental gravel For ; When the uniformity coefficient , the minimum particle size of the experimental gravel For , the maximum particle size of the experimental gravel For ; Among them, , Refers to the sand particle diameter corresponding to the cumulative mass fraction of 50% on the mass distribution curve of the formation sand 03 particle size of the target formation, Refers to the sand particle diameter corresponding to the cumulative mass fraction of 40% on the mass distribution curve of the formation sand 03 particle size of the target formation, Refers to the sand particle diameter corresponding to the cumulative mass fraction of 90% on the mass distribution curve of the formation sand 03 particle size of the target formation; After determining the minimum particle size and the maximum particle size of the experimental gravel, the difference between the maximum particle size and the minimum particle size is calculated Then the particle size range of the first group of experimental gravel is ~ The particle size range of the second group of experimental gravel is ~ Similarly, the particle size range of the N1th group of experimental gravel is ~ That is - ~ ; Step 2, based on the fluid viscosity, sand-carrying concentration and production flow rate of the target formation, the optimal experimental gravel particle size range is selected, as follows: Step 21, preparation of sand-carrying fluid; Determine the experimental fluid, the viscosity of the experimental fluid is consistent with the fluid viscosity of the target formation; according to the sand-carrying concentration of the target formation, mix the experimental fluid with the experimental formation sand to form the sand-carrying fluid; Step 22, let i=1, i represents the serial number of the particle size range of the experimental gravel, the smaller the i, the smaller the median in the corresponding particle size range; Step 23, clean the visualization model box 1 and detect the sealing performance; Step 24, preparation of the filling layer; Place the experimental gravel of the ith particle size range in the visualization model box 1, and compact the experimental gravel layer by driving the top screen 2 through the loading part 3; Step 25, injection of sand-carrying fluid; A collection barrel is arranged at the bottom of the sand collection pipe 7, the injection system 6 is started, and the sand-carrying fluid is injected into the experimental gravel layer in the filtration simulation space 5 from the upper part of the visualization model box 1 until the required experimental time is reached, wherein the injection flow rate of the sand-carrying fluid is consistent with the production flow rate of the target formation; In this process, the migration and deposition of sand particles in the experimental gravel layer in the visualization model box 1 are photographed by the camera; and the pressure data are collected by the pressure transmitter 8; Step 26, sand production amount statistics; The experimental formation sand collected in the collection barrel is filtered, dried, and weighed to obtain the sand production mass of the experimental gravel corresponding to the ith particle size range; Step 27, when i < N1, i = i + 1, and step 23 is entered; Otherwise, step 28 is entered; Step 28, based on the comprehensive judgment method of sand blocking and fluid flow capacity, the optimal experimental gravel particle size range based on the fluid viscosity, sand-carrying concentration, and production flow rate of the target formation is determined; Step 3, considering the differences in production flow rate and sand-carrying concentration before and after production, sand-carrying fluids with different sand-carrying concentrations are prepared according to the actual production situation, different injection flow rates within the production range are selected, and the gravel with the optimal particle size range determined in step 2 is further evaluated for sand control under different sand-carrying concentrations and injection flow rates; the specific steps are as follows: Step 31, the sand-carrying concentration and injection flow rate form a variable combination, the specific values of each variable in the variable combination in each experiment are determined as experimental input data, and each set of experimental input data is numbered, wherein the total number of experimental input data is N2; Step 32, j = 1, j represents the serial number of the experimental input data; Step 33, the visualization model box 1 is cleaned and the sealing is detected; Step 34, the filling layer is prepared; The optimal particle size range experimental gravel is placed in the visualization model box 1, and the experimental gravel layer is compacted by driving the top screen 2 through the loading part 3; Step 35, injection of sand-carrying fluid; A collection barrel is arranged at the bottom of the sand collection pipe 7, the injection system 6 is started, and the sand-carrying fluid with the sand-carrying concentration value corresponding to the serial number j is injected into the experimental gravel layer in the filtration simulation space 5 from the upper part of the visualization model box 1 until the required experimental time is reached, wherein the injection flow rate is the injection flow rate value corresponding to the serial number j; In this process, the migration and deposition of sand particles in the experimental gravel layer in the visualization model box 1 are photographed by the camera; and the pressure data are collected by the pressure transmitter 8; Step 36, sand production amount statistics; The experimental formation sand collected in the collecting barrel is filtered, dried and weighed to obtain the sand production mass corresponding to the jth experimental input data; Step 37, when j < N2, let j = j + 1, and enter step 33; Otherwise, enter step 38; Step 38, based on the comprehensive judgment method of sand retention and fluid flow capacity, the sand control performance of the optimal particle size range of gravel under different sand-carrying concentrations and injection flow rates is evaluated.

[0045] Preferably, based on the comprehensive judgment method of sand retention and fluid flow capacity, the specific method is as follows: Constructing sand control parameters The calculation formula is: Formula (1) Formula (2) Formula (3) Formula (4) Wherein, is the sand production rate, reflecting the sand retention performance; is the sand production mass; is the total mass of injected sand; is the injection flow rate; is the cross-sectional area of the filtration simulation space 5; is the experimental time; is the sand-carrying concentration of the sand-carrying fluid; is the permeability, reflecting the fluid flow capacity; is the absolute value of the pressure difference detected by the uppermost and lowermost two pressure transmitters 8 at the end of the experiment; is the viscosity of the experimental fluid; is the vertical distance between the uppermost and lowermost two pressure transmitters 8; In step 28, the value of the sand control parameter of each experiment is calculated, and the experimental gravel particle size range corresponding to the sand control parameter with the smallest value is taken as the optimal particle size range based on the fluid viscosity, sand-carrying concentration and production flow rate of the target formation; In step 38, the value of the sand control parameter of each experiment is calculated, and the sand control performance of the optimal particle size range of gravel under different sand-carrying concentrations and injection flow rates is evaluated by using the value of the sand control parameter , the smaller the value of the sand control parameter , the better the sand control performance.

[0046] In addition, when each experiment is conducted by using the device, the top sieve 2 and the bottom sieve 4 are replaced according to the particle size range of the experimental gravel, wherein the pore size of the top sieve 2 is equal to the minimum particle size of the experimental gravel, so as to avoid the gravel flowback; the pore size of the bottom sieve 4 is 2 / 3 of the minimum particle size of the experimental gravel.

[0047] Although the specific embodiments of the present application are described above with reference to the drawings, the present application is not limited to the above embodiments, and various modifications or changes can be made by those skilled in the art without creative efforts on the basis of the technical solutions of the present application, and still fall within the protection scope of the present application.

Claims

1. A visual experimental apparatus for evaluating gravel-filled sand control technology for sieve tubes, characterized in that, Includes a visual model box; The upper inner side of the visualization model box is fitted with a top screen that is used to disperse sand-carrying fluid. The top of the visualization model box is provided with a loading part connected to the top screen to simulate reservoir overburden pressure. The lower inner side of the visualization model box is equipped with a bottom screen to simulate a well shaft screen. The internal space of the visualization model box between the top screen and the bottom screen forms a filtration simulation space for placing gravel; The visualization model box is connected to an injection system used to inject sand-carrying fluid into the filtration simulation space; The bottom of the bottom screen in the visualization model box is equipped with a sand collection pipe for collecting sand particles; The visualization model box is equipped with several pressure transmitters evenly arranged along the vertical direction to measure the pressure at different locations within the simulated space.

2. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 1, characterized in that, The visualization model box includes a main cylinder with a cylindrical structure, a top cover at the top of the main cylinder, and a bottom plate at the bottom of the main cylinder; The inner wall of the main cylinder corresponding to the filtration simulation space has several annular grooves arranged axially, and the central axis of the annular grooves is consistent with the central axis of the main cylinder.

3. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 2, characterized in that, The main cylinder includes an upper sand cylinder and a lower sand cylinder coaxially connected, and the lower sand cylinder includes several coaxially connected cylindrical bodies. The top cover is set at the top of the upper sand cylinder, and the radial outer end of the bottom screen is coaxially fixed with an upwardly extending lower mounting ring. The bottom end of the lower sand cylinder is inserted into the mounting ring, and the bottom plate is set at the bottom end of the bottom screen. A clamping mechanism is provided between the top cover and the bottom plate to clamp and fix the top cover, upper sand cylinder, lower sand cylinder, bottom screen, and bottom plate.

4. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 3, characterized in that, The two adjacent cylindrical structures in the main cylinder are nested together by a locking mechanism; The locking mechanism includes an upper annular groove located inside the bottom end of the upper cylindrical structure and a lower annular groove located outside the bottom end of the lower cylindrical structure. The upper annular groove forms an upper annular block at the bottom end of the upper cylindrical structure, and the lower annular groove forms a lower annular block at the top end of the lower cylindrical structure. In the locking mechanism, the upper annular locking block is fitted into the lower annular locking groove, and the lower annular locking block is fitted into the upper annular locking groove. A first annular sealing sheet is provided between the bottom end of the upper annular locking block and the bottom end of the lower annular locking groove. When the upper annular locking block is pressed against the corresponding first annular sealing sheet, an annular groove is formed between the top end of the upper annular locking groove and the top end of the lower annular locking block.

5. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 3, characterized in that, The bottom end of the top cover is provided with a top cover retaining ring that can be inserted into the upper sand cylinder, and a second annular sealing plate is provided between the top end of the upper sand cylinder and the top cover. A third annular sealing sheet is provided between the bottom screen and the lower sand cylinder, and between the bottom screen and the bottom plate.

6. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 3, characterized in that, The clamping mechanism includes three clamping screws distributed along the circumferential direction. The base plate is provided with a first countersunk hole for the clamping screws to pass through upwards, and the top cover is provided with a first connecting hole for the clamping screws to pass through upwards. After the clamping screw passes upward through the corresponding first countersunk hole and first connecting hole, a clamping nut is screwed into the clamping screw at the top of the first connecting hole. Tightening the clamping nuts on all clamping screws achieves clamping and sealing of the top cover, upper sand cylinder, lower sand cylinder, bottom screen, and bottom plate.

7. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 2, characterized in that, The base plate is provided with a conical hole that communicates with the sand collection pipe. The larger end of the conical hole faces the bottom screen, and the smaller end of the conical hole faces the sand collection pipe.

8. The visual experimental apparatus for evaluating gravel-filled sand control technology in sieve tubes as described in claim 1, characterized in that, The loading unit includes a cylinder fixedly installed on the outside of the top of the visualization model box. The piston rod of the cylinder passes downward into the interior of the visualization model box and is connected to the upper pressure plate. An annular mounting groove is provided on the upper part of the outer side wall of the upper pressure plate, a first sealing ring is provided in the annular mounting groove, and an upper pressure ring is coaxially provided at the bottom end of the upper pressure plate. The top of the top screen is coaxially fixed with an upper mounting ring, and the inner side wall of the upper mounting ring is threadedly connected to the outer side wall of the upper pressure ring. A second sealing ring is provided between the top of the upper mounting ring and the upper pressure plate.

9. A visual experimental method for evaluating gravel-filled sand control technology for screen tubes, implemented based on the visual experimental apparatus for evaluating gravel-filled sand control technology for screen tubes as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1, Preparation of gravel and experimental formation sand; The experimental formation sand is either the formation sand of the corresponding reservoir or a mixture thereof. When mixing, the experimental formation sand is prepared by sieving fine sand and then mixing it in proportion according to the particle size distribution curve of the formation sand of the target formation. Prepare experimental gravel of different particle size ranges in group N1; Step 2 involves selecting the optimal experimental gravel size range based on the fluid viscosity, sand-carrying concentration, and production flow rate of the target formation, as detailed below: Step 21, Preparation of sand-carrying fluid; The experimental fluid is determined, and its viscosity is consistent with that of the target formation fluid. Based on the sand-carrying concentration of the target formation, the experimental fluid is mixed with the sand in the experimental formation to form a sand-carrying fluid. Step 22, let i=1, where i represents the particle size range number of the experimental gravel. The smaller i is, the smaller the median of the corresponding particle size range. Step 23: Clean the visualization model box and perform a sealing test; Step 24, prepare the filling layer; The experimental gravel of the i-th particle size range is placed in the visualization model box, and the experimental gravel layer is compacted by the top screen driven by the loading part. Step 25, injection of sand-carrying fluid; A collection bucket is set at the bottom of the sand collection pipe. The injection system is started, and the sand-carrying fluid is injected from the top of the visualization model box into the experimental gravel layer in the filtration simulation space until the required experimental time is reached. The injection flow rate of the sand-carrying fluid is consistent with the production flow rate of the target formation. During this process, cameras are used to capture images of the movement and deposition of sand particles within the experimental gravel layer in a visualization model box; pressure data is collected using pressure transmitters. Step 26, Sand output statistics; The experimental formation sand collected in the collection bucket is filtered, dried and weighed to obtain the output sand mass of the experimental gravel corresponding to the i-th particle size range. Step 27: When i < N1, let i = i + 1, and proceed to step 23; Otherwise proceed to step 28; Step 28: Based on the comprehensive judgment method of sand retention and fluid flow capacity, determine the optimal experimental gravel particle size range based on the fluid viscosity, sand carrying concentration, and production flow rate of the target formation. Step 3: Considering the differences in production flow rate and sand-carrying concentration before and after production, sand-carrying fluids with different sand-carrying concentrations are prepared according to the actual production situation. Different injection flow rates are selected within the production range. Further sand control evaluation is conducted on gravel within the optimal particle size range determined in Step 2 under different sand-carrying concentrations and injection flow rates. Details are as follows: Step 31: The sand concentration and injection flow rate form a variable combination. The specific values ​​of each variable in the variable combination in each experiment are determined as experimental input data. Each set of experimental input data is numbered, and the total number of experimental input data is N2. Step 32, let j=1, where j represents the sequence number of the experimental input data; Step 33: Clean the visualization model box and perform a sealing test; Step 34, prepare the filling layer; The experimental gravel with the optimal particle size range was placed in the visualization model box, and the experimental gravel layer was compacted by driving the top screen through the loading part. Step 35, injection of sand-carrying fluid; A collection bucket is set at the bottom of the sand collection pipe. The injection system is started, and the sand-carrying fluid corresponding to the sand concentration value of serial number j is injected from the top of the visualization model box into the experimental gravel layer in the filtration simulation space until the required experimental time is reached. The injection flow rate is the injection flow rate value corresponding to serial number j. During this process, cameras are used to capture images of the movement and deposition of sand particles within the experimental gravel layer in a visual model box; pressure data is collected using pressure transmitters. Step 36, Sand output statistics; The experimental formation sand collected in the collection bucket is filtered, dried, and weighed to obtain the output sand mass corresponding to the j-th experimental input data. Step 37: When j < N2, let j = j + 1, and proceed to step 33; Otherwise proceed to step 38; Step 38: Based on a comprehensive judgment method of sand control and fluid flow capacity, the sand control performance of gravel with the optimal particle size range under different sand carrying concentrations and injection flow rates is evaluated.

10. The visual experimental method for evaluating gravel-filled sand control technology in screen tubes as described in claim 9, characterized in that, The comprehensive judgment method based on sand control and fluid flow capacity is as follows: Build sand control parameters The calculation formula is as follows: Formula (1) Formula (2) Formula (3) Formula (4) in, Sand output rate; For the quality of the produced sand; The total mass of the injected sand; Injection flow rate; To filter the cross-sectional area of ​​the simulated space; For experimental time; The sand-carrying concentration of the sand-carrying fluid; For penetration rate; This is the absolute value of the pressure difference detected by the top and bottom pressure transmitters at the end of the experiment. The viscosity of the experimental fluid; This is the vertical distance between the top and bottom two pressure transmitters. In step 28, the sand control parameters corresponding to each experiment are calculated. The value of the sand control parameter The experimental gravel size range corresponding to the experiment with the smallest numerical value is taken as the optimal particle size range based on the fluid viscosity, sand-carrying concentration, and production flow rate of the target formation. In step 38, the sand control parameters corresponding to each experiment are calculated. The values ​​are based on sand control parameters. Numerical evaluation of the sand control performance of gravel with optimal particle size range under different sand-carrying concentrations and injection flow rates, and sand control parameters. The smaller the value, the better the sand-proof performance.

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