CN215256146U

CN215256146U - Sand filling pipe core for simulating water injection of water injection well

Info

Publication number: CN215256146U
Application number: CN202120605478.2U
Authority: CN
Inventors: 董致伟; 苗钧逸; 马东哲
Original assignee: Top Lab Research Institute Of Oil And Gas Development Beijing
Current assignee: Top Lab Research Institute Of Oil And Gas Development Beijing
Priority date: 2021-03-25
Filing date: 2021-03-25
Publication date: 2021-12-21
Anticipated expiration: 2031-03-25

Abstract

The utility model discloses a simulation water injection well water injection fill sand pipe rock core, wherein including filling the sand pipe main part, fill the sand pipe main part and connect to form through dismantling the connecting piece by the different body of many internal diameters, many the body is arranged according to the order that the internal diameter increases progressively by head to tail, fill the sand pipe main part inner chamber and fill homogeneous sand or inhomogeneous sand, head, tail two the outside end of body is connected with first end cap and second end cap respectively, be equipped with on the first end cap with fill the communicating first through-hole of sand pipe main part inner chamber, be equipped with on the second end cap with fill the communicating second through-hole of sand pipe main part inner chamber. The utility model discloses structural design is simple, and the preparation method is simple and convenient, can effectively solve the "disappearance" problem of the influence that the velocity of flow that the injection fluid produced because of the reducing changes, improvement porous medium authenticity and terminal surface sand, has improved experimental quality and precision, provides effective experimental scheme for simulating real oil recovery process, can effectively improve the oil recovery rate.

Description

Sand filling pipe core for simulating water injection of water injection well

Technical Field

The utility model relates to an oil reservoir physical simulation technical field especially relates to a simulation water injection well injection fluid seepage flow mode, be used for heterogeneous or homogeneous oil reservoir chemical flooding and transfer and drive etc. and improve the sand-packed tub rock core of simulation water injection well water injection of high recovery ratio research and effect evaluation.

Background

With the rapid development of economy in China, the demand of petroleum resources is increasing day by day, and the difficulty of petroleum exploration and development is increasing more and more. The dominant oilfields such as Daqing and Shengli oilfields in China enter high and ultrahigh water-content development stages, but a large amount of crude oil still remains in the stratum, and the recovery ratio is low. Therefore, it is becoming important how to further increase the recovery of crude oil from developed oil fields.

In the process of oilfield water injection development, due to the heterogeneity of the oil reservoir plane and the longitudinal direction, the difference of oil-water viscosity and the unbalanced injection-production relationship of an injection-production well pattern, the problems of the water injection well entering the production well tongue and protruding along a high permeability layer are caused, so that the low-efficiency circulation of injected water is caused, and a large amount of residual oil still exists in a low permeability zone and a low permeability zone of the same layer in the oil reservoir.

Therefore, increasing the swept volume of the injected fluid is an important method for increasing oil recovery. The injection polymer flooding and water injection well profile control have good technical effects, are widely applied, obtain good effects of water reduction and oil increase, and become an economic and effective means for improving the oilfield flooding development effect and realizing the stable production of old oilfields.

In order to evaluate the oil displacement or profile control performance of various injection wells, a heterogeneous physical model is usually constructed according to the heterogeneous conditions of an oil reservoir, cores with different permeabilities are pressed together by a traditional heterogeneous artificial core model, the manufacturing process is extremely complex, the core model cannot be manufactured under the conditions of a common laboratory, and the cost is high. At present, a common heterogeneous physical model is a heterogeneous parallel double-pipe model, and the model is simple to manufacture and convenient to measure, and plays a very important role in evaluating the plugging characteristics and the flow distribution characteristics of profile control agents such as polymer flooding agents, gel agents, foams and the like.

The patent of application number 201420672830.4, entitled "heterogeneous rock core thing mould experimental apparatus of a single tube sand-packed" discloses that the apparatus separates into the compartments that are used for placing different permeability rock cores respectively through setting up the baffle in that the core pipe is inside to the heterogeneity of simulation oil reservoir. Compared with a non-homogeneous parallel double-tube model, the patent has the advantages of simple structure, convenient use and simplified experimental process. However, the position of the partition plate in the core tube is not easy to control, and the existence of the partition plate is equivalent to artificially limiting the flow of fluid between cores with different permeability, and the interlayer flow-around characteristic of a real heterogeneous oil reservoir cannot be fully reflected.

Application No. 201811538265.1, entitled "a method for preparing a thick oil steam flooding high temperature and high pressure resistant core", discloses that the preparation method comprises: screening the quartz sand to obtain the quartz sand with required meshes, selecting one or more quartz sand with different meshes, and uniformly mixing the quartz sand with different meshes; selecting proper type of aluminate cement, wherein the aluminate cement selects a CA60-I type meeting the GB/T201-2015 regulation; weighing aluminate cement quartz sand, mixing and stirring the aluminate cement quartz sand and the aluminate cement quartz sand to prepare a mixture filler; filling the mixture filler into a sand filling pipe, compacting the filler through a compaction rod, and maintaining the pressure for a certain time; and airing the compacted sand filling pipe core, and drying to obtain the thick oil steam flooding high-temperature and high-pressure resistant core.

The sand tube core of the prior design is divided into three types, wherein the first type is a non-cemented sand filling tube core, namely quartz sand, river sand or oil reservoir sand with different grain diameters are mixed and transferred into a sand filling tube and compacted to form the sand filling tube core; the second type is a semi-cemented sand-filled tube core, namely a sand-filled tube core obtained by stirring a mixed quartz sand with a binder and compacting, and the third type is an evaluation of fluid injection by a sand-filled tube, which mainly introduces an evaluation mode and the like.

These sand-packed tubular cores all solve certain problems to varying degrees. The following problems still remain: the core of the existing sand filling pipe is cylindrical, the flow rate of fluid entering the core of the sand filling pipe is relatively stable, the difference of the flow rates is artificially designed in a heterogeneous mode, the fluid with relatively stable flow rate injected into the core of the cylindrical sand filling pipe is difficult to simulate a seepage mode of penetrating into an oil layer through a casing of a water injection well, namely, the flow rate of the injected fluid enters the oil layer with larger thickness through fine holes under the action of high pressure from high to low, various fluids entering porous media of the oil layer are sheared by pores, the shearing speed is gradually reduced, and the core of the sand filling pipe does not exist; secondly, sand in the core of the sand filling pipe is blocked by a screen mesh at the outlet end of the core of the sand filling pipe, so that the sand does not flow out under the action of injection pressure in the experimental process and is not matched with the actual oil layer porous medium; thirdly, the sand filling pipe core injection end firstly seals end cover particles on the core by using a stainless steel screen mesh pad, and then fills quartz sand for preventing the quartz sand from blocking a channel for injecting fluid into the core hole, so that the dispersion influence of the injected fluid is not considered, and the injection property problem of the injection well in injection particles and other profile control and flooding agents is not considered; fourthly, the phenomenon of 'lack' of quartz sand at the outlet end can occur in the process of a sand filling pipe core experiment, because the phenomenon of secondary compaction of the dry core after saturated water occurs, the dry sand is filled to be solid again, and the phenomenon can occur after soaking, and as a result, the permeability of the core and the experiment result are influenced to a certain extent; fifthly, the existing sand filling pipes cannot be visualized, and the fluctuation and distribution of fluid in the rock core are observed after the experiment is finished, particularly the experiment for injecting chemical agents or profile control agents and the like.

Therefore, along with the increase of the difficulty of oil reservoir development, the experiment difficulty of core physical simulation is increased, a novel sand-packed pipe core which is suitable for the oil reservoir is urgently needed, relevant accurate parameters are obtained through experiments, a 'double-high' oil field with high water content and high extraction degree is effectively guided, the crude oil recovery rate is further improved, and the national economic construction is served.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a simulation water injection well water injection fill sand tube rock core, this structural design is simple, and the preparation method is simple and convenient, can effectively solve the injection fluid because of the influence of the velocity of flow change that the reducing produced, improve porous medium authenticity and the "disappearance" problem of terminal surface sand, has improved experimental quality and precision, provides effective experimental scheme for simulating real oil recovery process, can effectively improve the oil recovery rate.

In order to realize the above-mentioned purpose, the utility model provides a sand pack pipe rock core of simulation water injection well water injection, wherein including the sand pack pipe main part, the sand pack pipe main part is connected to form through dismantling the connecting piece by the different body of many internal diameters, many the body is arranged according to the order that the internal diameter increases progressively by head to tail, the sand pack pipe main part inner chamber is filled with homogeneity sand or inhomogeneous sand, head, tail two the outside end of body is connected with first end cap and second end cap respectively, be equipped with on the first end cap with the communicating first through-hole of sand pack pipe main part inner chamber, be equipped with on the second end cap with the communicating second through-hole of sand pack pipe main part inner chamber.

Preferably, the first through hole is located in the middle of the first plug, a first screen is installed at the first through hole, the first pipe outer side portion is connected with the open end of a conical second screen, the conical closed end of the second screen extends towards the inside of the pipe body, and a first sand body with a particle size larger than that of sand filled in the inner cavity of the sand filling pipe main body is filled in the second screen.

Preferably, the second through hole is located in the middle of the second plug, a third screen is installed at the second through hole, a filtering support pad is installed at the end of the pipe body at the tail part, an elastic piece is arranged between the filtering support pad and the third screen, and two ends of the elastic piece elastically abut against the filtering support pad and the third screen.

Preferably, the filter support pad is a sand core.

Preferably, the middle part of at least one pipe body is provided with a pressure measuring hole, and the pressure measuring hole is communicated with a pressure measuring device.

Preferably, a fourth screen is respectively installed on the inner cavity wall of each pipe body at the pressure measuring hole.

Preferably, the inner cavity wall of each tube body is roughened.

Preferably, sealing rings are respectively arranged between the first plug and the first pipe body, between the adjacent connecting parts of the pipe bodies and between the second plug and the tail pipe body.

After the scheme is adopted, the utility model discloses sand pack pipe rock core of simulation water injection well water injection has following beneficial effect:

(1) by adopting the sand filling pipe main body formed by sequentially and incrementally connecting a plurality of sand filling pipe cores with different inner diameters, the problem that the flow rate uniformity of the existing sand filling pipe core does not conform to the flow rate change from casing perforation to oil deposit can be solved, and the simulation experiment can be closer to the seepage process from perforation to oil deposit;

(2) the plurality of pipe bodies of the sand filling pipe main body are connected through the detachable connecting pieces, the problem that the existing sand filling pipe core cannot be visualized is solved, the core after a simulation experiment can be separated from the pipe bodies after the connecting pieces are rapidly detached, and an experimenter can conveniently and effectively observe the fluid distribution condition;

(3) the sand core is arranged at the outer side end of the inner diameter of the tail pipe and is closer to a real medium, the elastic part is elastically connected between the sand core and the second plug, the problem of sand loss possibly caused by soaking compaction is solved, after the sand core and the filled sand are extruded by the elastic part after the sand core and the filled sand are soaked and compacted, no space is reserved, and the liquid permeability change caused by soaking is prevented;

(4) the conical second screen provided with the first sand body is connected to the outer side end of the first pipe body, so that the particle size of the first sand body in the second screen is larger than that of the second sand body filled in each pipe body, and the conical second screen is favorable for injecting various fluids and chemical agents and prevents the inner cavity of the sand filling pipe from being blocked.

Drawings

FIG. 1 is a schematic structural view of an embodiment of a core of a sand-filled pipe for simulating water injection of a water injection well according to the present invention;

FIG. 2 is a schematic view of the structure of the mounting bracket used in the process of the sand-filled pipe core manufacturing method for simulating water injection of a water injection well of the present invention;

FIG. 3 is a diagram of the internal distribution effect of the core after the experiment of the sand-filled pipe core of the present invention is finished;

fig. 4 is the utility model discloses each body cross-sectional effect picture of sand pack rock core after the experiment ends.

Detailed Description

The invention will be elucidated below on the basis of an embodiment shown in the drawing. The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is not limited by the following description of the embodiments, but is defined only by the scope of the claims, and includes all modifications that have the same meaning as the scope of the claims and are within the scope of the claims.

The following description is given by combining with the specific embodiment of the utility model discloses a sand-packed pipe rock core of simulation water injection well water injection.

As shown in fig. 1, the utility model discloses the sand pack rock core of simulation water injection well water injection is including filling sand pipe main part 1, and filling sand pipe main part 1 is connected by the different circular body of many internal diameters and is constituteed, and many bodys are arranged according to the order that the internal diameter increases progressively by head to tail. The sand filling pipe main body 1 of the embodiment is formed by sequentially connecting five pipe bodies 2 in an increasing order of inner diameter, namely, the inner diameter of the first pipe body 2 is the smallest, the inner diameters of the second pipe body to the fifth pipe body 2 are sequentially increased, the inner diameter of the first pipe body 2 is 20-25mm, the embodiment adopts 25mm, the inner diameter of the second pipe body 2 is 30-35mm, the embodiment adopts 30mm, the inner diameter of the third pipe body 2 is 40-45mm, the embodiment adopts 40mm, the inner diameter of the fourth pipe body 2 is 50-55mm, the embodiment adopts 50mm, the inner diameter of the fifth pipe body 2 is 60-65mm, the embodiment adopts 60mm, and the length of the five pipe bodies 2 is set as: the lengths of the first, second, third and fifth tube bodies 2 are 50-100mm, the lengths of the four tube bodies 2 in this embodiment are 60mm, the length of the fourth tube body 2 is 100-200mm, and the length of the fourth tube body 2 in this embodiment is 160mm, so that the length of the sand filling tube main body 1 formed by connecting the five tube bodies 2 is 300-600mm, in this embodiment 400mm, and the lengths can also be adjusted as required. The inner cavity walls of the five tube bodies 2 are roughened, so that fluid injected in the experimental process is prevented from flowing along the tube wall with relatively small seepage resistance.

The adjacent body 2 of this embodiment links together through dismantling the connecting piece, and the connecting piece can be dismantled to this embodiment adopts reducing joint 3, for the connection of cooperation reducing joint 3, sets up internal thread portion 4 respectively at the inner chamber wall of two adjacent bodys 2, and the preferred metal material of internal thread portion 4 makes, and reducing joint 3 is made by metal material, and it includes reducing joint body 5, is equipped with external screw thread portion 6 respectively at the surface both ends of reducing joint body 5. The reducer joints 3 are screwed with the internal thread parts 4 of two adjacent pipe bodies 2 through two external thread parts 6, sealing rings, preferably oil-resistant, temperature-resistant and pressure-resistant rubber sealing rings, are respectively arranged between each reducer joint 3 and each pipe body 2 to prevent fluid from seeping out under the action of pressure, and each sealing ring is respectively arranged on the position, close to the external thread part 6, on each reducer joint body 5. The inner cavity of the sand-packed pipe body 1 is filled with homogeneous sand or heterogeneous sand, and the heterogeneous sand is filled in this embodiment, that is, clean reservoir sand uniformly mixed by 60 meshes, 100 meshes, 140 meshes and 240 meshes is filled in the first pipe body 2. High-permeability sand is filled in the middle of the inner cavities of the second pipe body to the fifth pipe body 2 respectively, the high-permeability sand is 80-mesh clean reservoir sand, the gas permeability of the whole sand body in the sand filling pipe main body 1 is about 1000md, and the permeability of the sand body at the high-permeability part is about 1500 md.

The left end of the first pipe body 2 and the right end of the fifth pipe body 2 are respectively connected with a first plug 7 and a second plug 8. In this embodiment, the first plug 7 and the second plug 8 both use metal covers with internal threads. The center part of the first plug 7 is provided with a first through hole 9 communicated with the inner cavity of the sand filling pipe main body 1, so that fluid can conveniently enter the sand filling pipe main body 1, the diameter of the first through hole 9 is 3-5mm, and the first through hole 9 is connected with a first screen 10 which is used for preventing sand from blocking the first through hole 9. The first screen 10 is a metal screen with a mesh number of more than 300 meshes or a screen matched with injected substances, and a joint can be connected to the position, corresponding to the first through hole 9, of the left side surface of the first plug 7 in a screwing mode and is connected with an experimental process pipeline through the joint. The left end of the first pipe 2 is connected to the open end of a conical second screen 11, the second screen 11 is a conical screen with a large open end area and a small closed end area, the second screen 11 is made of stainless steel, the tapered end of the second screen 11 extends towards the inside of the first pipe 2, the length of the second screen 11 is 1/4-1/5 of the length of the first pipe 2, and the mesh number of the second screen 11 is 60-100. The second screen cloth 11 is filled with the first sand body that the particle size is greater than the sand particle size of the inner chamber of the sand filling pipe main body 1, and the first sand body of this embodiment adopts 20-40 mesh quartz sand, so that the purpose of setting is to prevent the injected fluid from blocking up the end face of the first pipe body 2, and the experimental quality is affected. The outer surface of the left side of the first pipe body 2 is provided with an external thread, the first plug 7 is in threaded connection with the external thread of the first pipe body 2 through an internal thread, a sealing ring is arranged between the first pipe body 2 and the first plug 7, and the sealing ring is arranged at the right side of the external thread on the left side of the first pipe body 2.

The second plug 8 is provided with a second through hole 12 communicated with the inner cavity of the sand-filled pipe main body 1, and the second through hole 12 is convenient for fluid to flow out of the sand-filled pipe main body 1. The diameter of the second through-holes 12 is 3-5mm, and a third screen 13 is attached to the second through-holes 12, and is provided to prevent sand from clogging the second through-holes 12. The third screen 13 is a metal screen with a mesh number of more than 300 meshes, and a joint can be connected to the right end of the second plug 8 corresponding to the position of the second through hole 12 in a screw connection manner and is connected with an experimental pipeline through the joint. The right side of the outer surface of the fifth pipe body 2 is provided with an external thread, the second plug 8 is in threaded connection with the right external thread of the fifth pipe body 2 through an internal thread, a sealing ring is arranged between the fifth pipe body 2 and the second plug 8, and the sealing ring is arranged at the left side of the right external thread of the fifth pipe body 2.

The right end of the fifth pipe body 2 is provided with a filtering support pad which can prevent sand from passing through and make fluid pass through, the filtering support pad of the embodiment adopts a sand core 14, the sand core 14 is made of ceramic materials and is in a round pad shape, the shape of the sand core 14 is matched with the shape of the inner cavity of the fifth pipe body 2, the aperture of the sand core 14 is 20-30 mu m, the thickness is 5-10mm, and the sand core is used as a real porous medium to prevent the sand from flowing out. An elastic part is arranged between the sand core 14 and the third screen 13 on the second through hole 12, the elastic part of the embodiment adopts a spiral spring 15 with the diameter of 50-55mm, two ends of the spring 15 elastically abut against the sand core 14 and the third screen 13, after the sand core 14 and the filled sand body are squeezed by the spring 15 after the sand core is soaked and compacted, no space is reserved, and the liquid permeability change caused by the soaking and compaction is prevented.

The middle part of at least one pipe body is provided with a pressure measuring hole, the middle parts of the second pipe body to the fifth pipe body 2 are respectively provided with a pressure measuring hole 16 with the diameter of 0.5-1.5mm, and the pressure measuring hole 16 is provided with a joint and a high-pressure valve 22 which are communicated with a pressure measuring device through the joint and used for measuring the pressure change of fluid flow in the experimental process; fourth screens 17 are attached to the inner walls of the four pressure measuring holes 16, and the number of the fourth screens 17 is set to 300 or more.

This embodiment can also be preferred set up the screen cloth respectively between adjacent body 2, the completion when every body 2 of being convenient for is dismantled.

Referring to fig. 1, the utility model discloses a method for making sand-filled pipe rock core of simulation water injection well water injection specifically includes following steps: the present embodiment is to simulate the situation of filling heterogeneous sand in the inner cavity of the sand filling pipe main body 1: and homogeneous second sand bodies are filled in the first pipe body 2, and heterogeneous sand consisting of the homogeneous second sand bodies and the homogeneous third sand bodies is filled in the second to fifth pipe bodies 2.

(1) Manufacturing 3-10 round pipe bodies, manufacturing five pipe bodies 2 according to the embodiment shown in fig. 1, wherein the inner diameters of the five pipe bodies 2 are sequentially increased, the inner diameter of the first pipe body 2 is 25mm, the inner diameter of the second pipe body 2 is 30mm, the inner diameter of the third pipe body 2 is 40mm, the inner diameter of the fourth pipe body 2 is 50mm, the inner diameter of the fifth pipe body 2 is 60mm, the lengths of the first, second, third and fifth pipe bodies 2 are 60mm, and the length of the fourth pipe body 2 is 160 mm. Pressure measuring holes 16 are respectively processed in the middle parts of second to fifth pipe bodies 2, a fourth screen 17 is respectively bonded on each pressure measuring hole 16, an internal thread part 4 is respectively processed on the inner cavity wall of the connecting end of the adjacent pipe body 2, external threads are respectively processed on the left side of the outer surface of the first pipe body 2 and the right side of the outer surface of the fifth pipe body 2, a metal cover-shaped first plug 7 and a second plug 8 with internal threads are prepared, a first through hole 9 is processed at the central part of the first plug 7, a first screen 10 is connected on the first through hole 9, a conical second screen 11 is filled with first sand meeting the permeability requirement, the grain diameter of the first sand is larger than that of the second sand to be added into the inner cavity of the first pipe body 2, the first sand adopts 20-40-mesh quartz sand, and then the second screen 11 is connected and fixed with the left end of the first pipe body 2 through the opening end, the conical closed end of the second screen 11 extends towards the inside of the pipe body 2, an annular groove is processed on the inner cavity wall of the first plug 7 close to the inner side of the internal thread, a sealing ring is installed on the annular groove, the left end of the first pipe body 2 is connected with the internal thread of the first plug 7 through the external thread, the sealing between the first pipe body 2 and the first plug 7 can be realized under the action of the sealing ring, the first pipe body 2 and the first plug 7 are connected through the thread and sealed through the sealing ring, and the filled sand can be prevented from flowing out;

(2) placing a first plug 7 connected with a first pipe body 2 on an installation support 18, as shown in fig. 2, wherein the support 18 is formed by welding three support legs 19 and a tray 20, the three support legs are uniformly connected to the bottom surface of the tray 20 along the circumferential direction, a support hole 21 is formed in the center of the tray 20, the first plug 7 is inserted into the support hole 21, the first pipe body 2 is positioned on the first plug 7, a sealing ring is installed below an upper internal thread part 4 of the first pipe body 2, then, an inner cavity of the first pipe body 2 is filled with a homogeneous second sand body meeting the permeability requirement of the first pipe body 2, the second sand body is filled with sand and compacted in a vibrating manner, and the second sand body is clean oil reservoir sand formed by uniformly mixing 60 meshes, 100 meshes, 140 meshes and 240 meshes;

(3) with first body 2 through the spiro union of external screw thread portion 6 spiro union of upper internal thread portion 4 with a reducing joint 3 lower part, below the upper internal thread portion 4 of second body 2, install the sealing washer respectively on the internal thread 4 down, with the lower extreme of second body 2 through the external screw thread portion 6 spiro union of internal thread portion 4 and reducing joint 3 upper portion down, prepare many diameters for the tubule that varies of 5-15mm, the tubule that the diameter is 15mm is selected for use to this embodiment tubule, the tubule is made by metal material or plastic materials, tubule length is 250 and complements each other 500mm, 420mm is selected for use to this embodiment tubule length. A thin tube is placed at the axle center part of the second tube body 2, the bottom of the thin tube is placed on the upper surface of the second sand body in the first tube body 2 and is used as a positioning piece for filling high-permeability sand bodies, and the placement direction of the thin tube is parallel to the tube body 2; and filling a third sand body meeting the permeability requirement into the thin tube, wherein the third sand body adopts 80-mesh high-permeability clean reservoir sand. The grain diameter of the third sand body is larger than that of the second sand body, and the third sand body is filled and compacted in a vibrating way at the same time, so that the height of the filled third sand body corresponds to the upper end of the second pipe body 2; filling a second sand body into the inner cavity of the second pipe body 2 outside the tubule, vibrating and compacting while filling the second sand body until the second sand body is filled to the upper end of the second pipe body 2, then drawing out each tubule from the pipe body 2, and vibrating and compacting the second sand body and the third sand body, wherein the diameter of the selected tubule and the grain diameter of sand filling can be selected according to the requirements of experimental purposes;

(4) sequentially installing a third pipe body, a fourth pipe body and a fifth pipe body 2 according to the increasing order of the inner diameters of the pipe bodies in the mode of the step (3), filling a thin pipe arranged at the axial lead of each pipe body 2 with a third sand body in each pipe body 2 according to the step (3), filling the second sand body in each pipe body 2 with a second sand body, finally removing each thin pipe, vibrating and compacting the second sand body and the third sand body to form a rock core of heterogeneous sand, and measuring the gas permeability of the whole rock core to be 1089md after the compaction, the sealing and the pressure testing are qualified;

(5) a sand core 14 is installed at the upper end of a fifth pipe body 2, a second through hole 12 is processed in the middle of a second plug 8, a third screen 13 is connected to the second through hole 12, an annular groove is processed on the inner side of an internal thread of the second plug 8, a sealing ring is installed on the annular groove, a spring 15 is installed at the upper end of the sand core 14, the upper end of the fifth pipe body 2 is connected with the internal thread of the second plug 8 through an external thread, sealing between the fifth pipe body 2 and the second plug 8 can be achieved under the action of the sealing ring, the fifth pipe body 2 and the second plug 8 are connected through threads and sealed through the sealing ring, filled sand can be prevented from flowing out, and the expansion and contraction amount of the spring 15 is 5-8 mm.

Before the experiment, firstly measuring the geometric dimension of the core of the sand-filled pipe, installing the reducer union 3, and installing the high-pressure valve 22 on the pressure measuring hole 16 and the first plug 7 and the second plug 8 of the core, wherein the weighing is the dry weight; performing gas pressure test on the sand-filled pipe core, and performing an experiment, wherein during the experiment, the sand-filled pipe core and formation water to be saturated are evacuated for 3 hours, then the water is fully saturated, and the sand-filled pipe core of the saturated water is weighed again to obtain wet weight; calculating the pore volume by subtracting the dry weight from the wet weight; then, crude oil is injected through the first through hole 9 of the first plug 7, and after the crude oil drives water in the sand body out of the sand filling pipe main body 1, an oil reservoir is simulated to be formed, wherein the sand body at the moment is oil reservoir sand; injecting water through the first through hole 9 of the first plug 7 to drive water to displace oil, recording oil production through a measuring cylinder outside the second through hole 12 when oil drives water saturated oil and is aged for 3 days, then driving the water to a rock core outlet, namely 98% of water content at the second through hole 12 of the second plug 8, measuring pressure change through a pressure measuring device connected with pressure measuring holes 16 on the second to fifth pipe bodies 2, transferring 0.5% of polymer microspheres with the average particle size of 10 micrometers at the first through hole 9 of the first plug 7, placing for 8 hours, recovering water injection from the first through hole 9 of the first plug 7, finishing the experiment when the water drives the water content to 98%, and recording the oil production and the pressure change.

And sequentially detaching the pipe bodies 2 from the outlet end of the core structure, namely detaching a fifth pipe body 2, sequentially detaching a fourth pipe body, a third pipe body, a second pipe body and a pipe body 2, longitudinally observing the position of the polymer microsphere when detaching each pipe body 2, and splitting the sand-filled area from the middle position to observe the water wave. The clogging of the first tubular body 2 was observed. And finally, splicing the five tube bodies 2 in sequence, and observing, describing and photographing the whole body.

The results are shown in fig. 3 and 4, the high permeability third sand zone in the main body 1 of the sand filling pipe in fig. 3 is filled with the polymer microspheres completely, and since the injection amount of the polymer microspheres is 0.3PV, and the pore volume of the high permeability third sand zone is smaller than that of the second sand zone, the produced polymer microsphere component is also seen at the outlet of the core, which indicates that the packing density of the part is higher. Also because of this, the high permeability third sand body area after plugging in fig. 4 generates a larger resistance after resuming water drive, and the subsequent injected water further displaces the remaining crude oil along the periphery of the high permeability third sand body, resulting in an effect of enlarging swept volume. However, because the viscosity of the crude oil and the water is relatively high (5: 1), after the residual oil at the periphery of the high-permeability third sand body is driven out by injecting the water, a secondary water flow channel is generated, the swept volume of the water is not further expanded, and the residual oil is in a peripheral area B of a shadow part A; as the diameter of the sand-packed tubular body 1 increases, the crude oil is gradually reduced in the occurrence of the injection fluid passage and in the microscopic heterogeneity and swept volume due to the greater viscosity, showing that the swept area of the end face of each tubular body 2 is gradually reduced, and the heterogeneity and directional diversity shown by the microscopic heterogeneity end face are apparent, which is not observed in the conventional sand-packed tubular core. If the recovery efficiency is further improved, polymer microspheres are continuously injected or other areas with high permeability are blocked in a targeted mode.

After the experiment is finished, the oil reservoir sand in each pipe body 2 is respectively taken out, crude oil is dissolved out by using a quantitative solvent and then extracted, and the oil saturation is calculated. As the core length increased, the volume displaced gradually decreased and the oil saturation gradually increased. The following is the experimental result of the oil saturation of the core of the sand-filled pipe after the water flooding is finished and the core in each pipe body 2 is detached:

the oil saturation of the rock core in each tube body is shown as follows:

core	The second one	Third one	Fourth one	Fifth of all
					Oil saturation degree%	35.8	45.6	55.9	74.5

Pressure monitoring in the experimental process shows that the average pressure change of the water flooding stage is 0.15MPa, and after the polymer microspheres are injected, the average pressure of the whole area is increased to 0.35MPa due to plugging of the high-permeability sand body area. The conical second screen 11 at the inlet end of the core is filled with quartz sand with larger grain size, so that the permeability is high and no blocking substances exist. On the other hand, the sand core 14 blocks at the outlet end of the core and the spring 15 presses against the outlet end of the core, so that the sand leakage phenomenon is not generated in front of the sand core 14, and a little space is reserved behind the sand core 14, which shows that the reservoir sand is further compacted in the experimental process, and the blocking of the porous medium sand core 14 with firm cementation is very necessary, especially the situation that the diameter of the sand filling pipe main body 1 is larger. The phenomenon of injection fluid channeling caused by the diameter change of the sand filling pipe main body 1 is avoided at the interface of each pipe body 2 of the sand filling pipe main body 1. And the interlayer and intrastratal heterogeneity in the actual geological oil reservoir is stronger, the swept volume of the actual injected fluid is smaller, a better targeting technology and micro profile control are needed, and the crude oil recovery rate is improved to the minimum extent.

The utility model discloses a body 2 detachably that just increase progressively in proper order with many internal diameters is different connects into and fills sand pipe main part 1, connects adjacent body 2 through a plurality of reducing joint 3, makes every body 2 all can dismantle the back and pour out oil reservoir sand, observes the distribution of different fluids after the displacement directly perceivedly, "visual" of research oil reservoir distribution. The simulation process of the method accords with the flow rate change process from casing perforation to reservoir sand, so that the simulation experiment is closer to the seepage process from perforation to reservoir sand; the sand core 14 is installed at the outer side end of the tail pipe body 2 and is closer to a real medium, and the spring 15 is connected between the sand core 14 and the second plug 8, so that the problem of sand loss possibly caused by soaking compaction is solved, no space is reserved when the sand core 14 and the filled sand body are extruded through the spring 15 after the soaking compaction, and the liquid permeability change caused by soaking is prevented; the conical second screen 11 filled with quartz sand is connected to the outer side end of the first pipe body 2, so that the particle size of the quartz sand in the second screen 11 is larger than that of the second sand filled in each pipe body 2, and the filling of various fluids and chemical agents is facilitated, and the blockage of the inner cavity of the sand filling pipe main body 1 is prevented. The sand-filled pipe core and the manufacturing method thereof solve the influence of the change of the flow velocity of the injected fluid caused by reducing, improve the authenticity of the porous medium and the 'missing' problem of the end face sand, improve the experimental quality and precision, provide an effective experimental scheme for simulating the real oil extraction process, and effectively improve the oil extraction rate.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It is to be understood that the present invention is not limited to the example methods, structures, and precise structures shown in the drawings, which have been described above, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. The utility model provides a sand-packed pipe rock core of simulation water injection well water injection which characterized in that: the sand filling pipe comprises a sand filling pipe main body, wherein the sand filling pipe main body is formed by connecting a plurality of pipes with different inner diameters through detachable connecting pieces, the plurality of pipes are arranged in an increasing order from head to tail according to the inner diameters, homogeneous sand or heterogeneous sand is filled in an inner cavity of the sand filling pipe main body, the outer side ends of the head pipe and the tail pipe are respectively connected with a first plug and a second plug, the first plug is provided with a first through hole communicated with the inner cavity of the sand filling pipe main body, and the second plug is provided with a second through hole communicated with the inner cavity of the sand filling pipe main body.

2. The sand-filled pipe core for simulating water injection of a water injection well according to claim 1, wherein the first through hole is located in the middle of the first plug, a first screen is installed at the first through hole, the first pipe outer side part is connected with an open end of a conical second screen, a conical closed end of the second screen extends towards the inside of the pipe, and a first sand body with a particle size larger than that of the sand body filled in the inner cavity of the sand-filled pipe main body is filled in the second screen.

3. The sand-filled pipe core for simulating water injection of a water injection well according to claim 1, wherein the second through hole is located in the middle of the second plug, a third screen is installed at the second through hole, a filtering support pad is installed at the end of the pipe body at the tail of the second through hole, an elastic piece is arranged between the filtering support pad and the third screen, and two ends of the elastic piece elastically abut against the filtering support pad and the third screen.

4. The sand-filled pipe core for simulating water injection of a water injection well according to claim 3, wherein the filter support pad is made of a sand core.

5. The sand-filled pipe core for simulating water injection of a water injection well according to claim 1, wherein a pressure measuring hole is formed in the middle of at least one pipe body, and the pressure measuring hole is communicated with a pressure measuring device.

6. The sand-filled pipe core for simulating water injection of a water injection well according to claim 5, wherein a fourth screen is respectively installed on the inner cavity wall of each pipe body at the pressure measuring hole.

7. The sand-filled pipe core for simulating water injection of a water injection well according to claim 1, wherein the inner cavity wall of each pipe body is roughened.

8. The sand-filled pipe core for simulating water injection of a water injection well according to claim 1, wherein sealing rings are respectively arranged between the first plug and the first pipe body, between the connecting parts of the adjacent pipe bodies and between the second plug and the tail pipe body.