Loose sandstone reservoir squeeze filling whole-process simulation experiment device, whole-process simulation experiment method and filling effect evaluation method

Abstract

The invention belongs to the technical field of oil and gas development and exploitation engineering, and particularly relates to a loose sandstone reservoir squeeze filling whole-process simulation experiment device, a whole-process simulation experiment method and a filling effect evaluation method.The whole-process simulation experiment device comprises an experiment device main body module, a constant-flow liquid supply system and a data measurement and acquisition system; the experimental device main body module comprises a simulation reservoir mold, a simulation sleeve, a screen pipe and a sealing cover plate, the simulation reservoir mold and the sealing cover plate are sealed and detachably connected, a plurality of simulation reservoir units are further arranged in the simulation reservoir mold, and the simulation reservoir units are laid around the simulation sleeve layer by layer and are filled in the simulation reservoir mold; the simulated reservoir unit is filled with simulated stratum sand; and the constant-flow liquid supply system and the data measurement and acquisition system are connected with the experiment main body device. The simulation experiment device can achieve simulation of the whole process of sand production, filling and production, and the filling effect evaluation method can provide theoretical guidance for optimization of extrusion filling parameters on a construction site.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas development and exploitation engineering, and specifically relates to a full-process simulation experimental device for squeezing and filling a loose sandstone reservoir, a full-process simulation experimental method and a filling effect evaluation method. Background Art

[0002] my country's loose sandstone reservoirs are widely distributed, and their efficient development is of great significance to ensuring national energy security. Loose sandstone reservoirs have serious sand production problems. Especially after multiple rounds of sand production and sand control, different forms of sand production deficits will appear in the near-well reservoir. Sand production deficit refers to the continuous production of formation sand particles, which will inevitably leave pores in the formation. After severe or long-term sand production, deficits will be formed due to sand production. The deficit form is relatively complex, which seriously restricts the effect of sand control. According to the historical fitting of sand production deficits in old wells, the sand production deficit form can be roughly divided into large pores ( Figure 1 As shown in a), honeycomb-like ( Figure 1 (shown in b), earthworm-like holes ( Figure 1 (c) Three typical forms. Figure 1 In the figure, 29 is the wellbore, 30 is the caprock, 31 is the loose sandstone reservoir, 32 is the perforation hole, and 33 is the sand-producing deficit. The large-hole sand-producing deficit refers to the continuous large-scale peeling and migration of formation sand particles under the action of fluid, and the particle shedding front advances very fast, eventually forming a large-hole type deficit. The heterogeneous honeycomb sand-producing deficit refers to the strong heterogeneity of the reservoir, and the formation sand particles with low cementation strength and fine particle size near the wall of the perforation hole 32 fall off and produce, reducing the flow resistance and increasing the local fluid flow rate, so that the fine sand particles that meet the sand-producing conditions in the surrounding area continue to be produced, and finally forming a honeycomb-like deficit. The tortuous earthworm-like sand-producing deficit refers to the local weakly cemented particles first peeling off and falling off under the action of fluid scouring, forming a smaller deficit channel; as the fluid displacement proceeds, the particles continue to fall off on the side wall of the deficit channel, and the deficit channel expands along the direction of the weak cementation surface, forming a sand-producing form similar to an earthworm hole.

[0003] Extrusion filling sand control refers to the use of sand-carrying fluid to carry quartz sand or artificial ceramsite particles into the formation in a certain mixing ratio. These solid particles will fill the sand-deficient area to form a gravel filling layer, which plays a role in blocking sand production from the formation while maintaining fluidity and production capacity. Extrusion filling sand control technology is to squeeze gravel particles into the formation outside the casing by high-pressure extrusion, which can form a high permeability layer in the formation outside the casing. Compared with gravel filling inside the casing, it can greatly reduce the skin coefficient and even form a negative skin. For sand-producing wells with long-term mining, the near-well reservoir forms a large sand deficit. The use of extrusion filling sand control technology can form a thicker sand retaining layer and a better comprehensive sand retaining effect. Extrusion filling sand control technology is currently widely used at home and abroad due to its better sand control effect. Due to the complex actual reservoir conditions of loose sandstone, it is difficult to fully consider the reservoir thickness and porosity, reservoir sand production, deficit and morphology during the extrusion filling construction process. Parameter design is still based on experience, and it is difficult to achieve refined and differentiated construction design. There is currently no mature method for evaluating the effect of extrusion filling construction. To complete the above-mentioned extrusion filling full process simulation and filling effect evaluation, indoor experimental simulation is indispensable, and it is also an effective and intuitive means.

[0004] The main problems of indoor experimental simulation currently include:

[0005] (1) At present, the filling process and the filling layer morphology in the near-wellbore area during the squeeze filling operation are still unclear. The existing experimental equipment is difficult to realize the sand production caused by long-term production in the reservoir ( Figure 2 34 is the output of sand particles), to the extrusion filling sand control operation, and then to the full process simulation of continuing production after sand control (see attached Figure 2 As shown, Figure 2 a to c in the figure are the reservoir sand production process, squeeze filling process, and production process, respectively), and it is difficult to simulate the complex sand production and deficit mode, which limits the design of on-site sand control operations and restricts the sand control effect.

[0006] (2) For old wells with long-term exploitation, the porosity and permeability differences and heterogeneity of the formation near the wellbore are strong, and the sand production process is long. The sand production deficit pattern is complex and difficult to predict. The existing formation simulation methods are mostly uniformly filled with sand and laid in a container. The deficit pattern and observation method are single, and it is not possible to flexibly simulate different complex sand production deficit patterns. It is also difficult to observe the longitudinal filling and sand production profiles after the experiment, and it is difficult to achieve refined and differentiated optimization of extrusion filling construction parameters.

[0007] (3) During the squeeze filling operation, when the construction pressure rises to a certain value, the filling process is judged to be over on site without analyzing the actual filling effect. There is currently a lack of simple, fast and accurate experimental evaluation methods to evaluate the squeeze filling effect, which leads to inaccurate judgments on when the squeeze filling operation is over on site, limiting the production and economic benefits of the oil well after production. Summary of the invention

[0008] In order to solve the drawbacks of the above-mentioned prior art, the present invention discloses a full-process simulation experimental device for extrusion filling of loose sandstone reservoirs, a full-process simulation experimental method and a filling effect evaluation method. The device can visually simulate different sand production and deficit forms and reservoirs with different physical properties for loose sandstone sand production and deficit reservoirs, simulate the whole process of sand production-filling-production, and realize the evaluation of extrusion filling effect, thereby providing key support for the optimization of extrusion filling process parameters and the improvement of filling effect.

[0009] The following technical means are specifically adopted:

[0010] A full-process simulation experimental device for squeezing and filling of loose sandstone reservoirs comprises a main module of the experimental device, a constant-flow liquid supply system and a data measurement and acquisition system. The main module of the experimental device is a core module, which is mainly used to simulate various deficit forms and non-deficient forms of loose sandstone reservoirs and realize indoor visual simulation of the full process of squeezing and filling of loose sandstone reservoirs. The constant-flow liquid supply system is an auxiliary module, which is mainly used to provide liquid or sand-carrying liquid for the main module of the experimental device and form a circulation. The data measurement and acquisition system is used for dynamic data acquisition and recording during the experiment.

[0011] The main module of the experimental device includes a simulated reservoir mold, a simulated casing, a screen tube and a sealing cover plate. The simulated reservoir mold is sealed and detachably connected to the sealing cover plate. A transparent observation window is provided on the sealing cover plate, which can realize visual simulation of reservoir sand production, extrusion filling or production process. The simulated reservoir mold is provided with a plurality of circulating liquid inlets; the simulated casing is arranged in the middle of the simulated reservoir mold, the simulated casing partially extends out of the simulated reservoir mold, the simulated casing is provided with a sand adding port and a plurality of reservoir filling ports, the reservoir filling port is located on the inner side of the simulated reservoir mold, and the sand adding port is located on the outer side of the simulated reservoir mold; the simulated reservoir mold is also provided with a plurality of simulated reservoir units, the simulated reservoir units are laid layer by layer around the simulated casing and filled in the simulated reservoir mold, and the simulated reservoir units are filled with simulated formation sand; the screen tube is arranged in the middle of the simulated casing, and is detachably connected to the simulated reservoir mold, and can be portable and replaced with other types of screen tubes, the screen tube partially extends out of the simulated reservoir mold, the screen tube is provided with a circulating liquid outlet and a plurality of liquid outlet holes, the liquid outlet holes are located on the inner side of the simulated reservoir mold, and the circulating liquid outlet is located on the outer side of the simulated reservoir mold; the circulating liquid inlet and the liquid outlet hole are both provided with sand blocking nets;

[0012] The constant flow liquid supply system is connected with the circulating liquid inlet, circulating liquid outlet and sand adding port; the data measurement and acquisition system is connected with the main module of the experimental device.

[0013] Furthermore, the constant flow liquid supply system includes a liquid storage tank, a screw pump, and an automatic sand feeder connected in sequence. The liquid storage tank can be a stainless steel vertical stirring liquid storage tank with an effective volume of up to 1000L, which has the function of stirring or storing the experimental fluid; the liquid storage tank is connected to the screw pump through a pipeline to provide liquid for the pumping of the screw pump; the automatic sand feeder is mainly composed of a pressure-resistant sand loading cylinder, a servo motor, a conveying auger, a sand conveying cylinder, and a liquid inlet and outlet. During the experiment, the flowing fluid can be mixed with sand and then flow out, and the flow rate meets 10-20 tons / hour. The liquid storage tank, the screw pump and the automatic sand feeder are all connected to the main device through connecting pipelines.

[0014] The screw pump is connected to the circulating liquid inlet, and a first control valve is provided between the screw pump and the circulating liquid inlet; the circulating liquid outlet is connected to the liquid storage tank, and a second control valve is provided between the circulating liquid outlet and the liquid storage tank; the automatic sand feeder is connected to the sand feeding port, and a third control valve is provided between the automatic sand feeder and the sand feeding port; the circulating liquid inlet is connected to the liquid storage tank, and a fourth control valve is provided between the circulating liquid inlet and the liquid storage tank; a fifth control valve is provided between the screw pump and the automatic sand feeder.

[0015] Furthermore, the data measurement and acquisition system includes a flow sensor, a pressure sensor and a computer acquisition terminal, and the computer acquisition terminal is connected to the flow sensor and the pressure sensor signals.

[0016] The flow sensor includes flow sensor I, flow sensor II, flow sensor III and flow sensor IV, and the pressure sensor includes pressure sensor I, pressure sensor II, pressure sensor III and pressure sensor IV. The flow sensor I and pressure sensor I are arranged between the screw pump and the circulating liquid inlet, the flow sensor II and pressure sensor II are located between the circulating liquid outlet and the liquid storage tank, the flow sensor III and pressure sensor III are arranged between the automatic sand feeder and the sand feeding port, and the flow sensor IV and pressure sensor IV are arranged between the circulating liquid inlet and the liquid storage tank.

[0017] The present invention also discloses a full-process simulation experiment method for squeezing and filling a loose sandstone reservoir using any of the above-mentioned simulation experiment devices, comprising the following steps:

[0018] S1. Build a complete simulated reservoir:

[0019] Select a filter with a pore size smaller than the formation sand particle size and the filling material particle size to prevent the formation sand and filling material from flowing between the simulated reservoir units, so that each simulated reservoir unit is independent of each other. For example, if the experiment uses a formation sand particle size of 0.15mm and a filling material particle size of 0.4-0.8mm, then the filter size should be less than 0.15mm. At the same time, the filter strength is required to ensure that the bottom layer of the filter is not squeezed and damaged after the entire simulated reservoir mold is paved. The strength of the filter is reflected by the thickness of the filter, that is, the filter wire diameter, which is usually required to be greater than 0.25mm.

[0020] The filter screen is cut and bent into a number of simulated reservoir units. At this time, the simulated reservoir units can be set to a prism shape with uniform length, height and width. The simulated formation sand is densely filled in the simulated reservoir units, and the simulated reservoir units are laid layer by layer around the simulated casing in the simulated reservoir mold until the simulated reservoir units fill the simulated reservoir mold, and the formation sand is filled in the gaps between the simulated reservoir units, and the sealing cover plate is connected; in the present invention, the simulated reservoir is divided into a number of independent simulated reservoir units, each of which can be independently filled with consolidated formation sand and opened to observe the filling shape.

[0021] S2, simulate the reservoir sand production process: open the first control valve and the second control valve, close the third control valve, the fourth control valve and the fifth control valve, pump fluid into the circulation liquid inlet through the screw pump, set the screw pump speed according to the actual reservoir construction conditions, simulate the reservoir sand production process, and record the data of flow sensor I, pressure sensor I, flow sensor II, and pressure sensor II during the simulated reservoir sand production process.

[0022] If you want to directly observe the sand production and deficit characteristics, you can open the simulated reservoir unit for observation after the simulated reservoir sand production experiment is completed, and then put it back into the simulated reservoir mold for extrusion filling experiment.

[0023] S3, simulated extrusion filling process: close the first control valve and open the second control valve, open the third control valve, the fourth control valve and the fifth control valve, set the screw pump speed and the sand feeder pump frequency, pump the sand-carrying liquid into the sand feeding port through the screw pump and the automatic sand feeding pump to simulate the extrusion filling process. During the experiment, the state of extrusion filling can be monitored through the transparent observation window. When the pressure rises rapidly by 0.5MPa within 10 seconds, stop the pump and suspend data collection, and record the data of flow sensor III, pressure sensor III, flow sensor IV, and pressure sensor IV during the simulated extrusion filling process. Evaluate the extrusion filling effect after data processing and analysis.

[0024] The pump speed of the screw pump and the pump frequency of the sand feeder during extrusion filling are mainly selected based on experience according to the relevant geological parameters of the actual reservoir, the construction parameters and the sand production degree obtained in step S2. The pressure flow data recorded in step S2 can be used to draw a pressure flow curve and calculate the reservoir permeability, and the sand production degree can be reflected by the reservoir permeability.

[0025] In addition, if you want to observe the squeeze filling morphology under different complex sand production and deficit morphology conditions, you should manually set different sand production and deficit morphologies, and you need to fill the simulated reservoir unit with simulated formation sand of different morphologies and different porosity and permeability properties. At this time, the simulated reservoir unit can be set with different shapes, sizes, thicknesses and lengths. Therefore, for this situation, before step S3, the following steps are also included:

[0026] Construct a simulated reservoir with sand production deficit:

[0027] Take out the simulated reservoir constructed in step S1, select a filter with a pore size smaller than the particle size of the formation sand and the particle size of the filling material, cut and bend the filter into several simulated reservoir units, for example, it can be bent into a cylindrical shape, and partially fill the simulated reservoir unit with simulated formation sand according to the shape of the sand deficit, arrange and combine them in the simulated reservoir mold according to the requirements of different deficit formation forms, until the simulated reservoir units cover the simulated reservoir mold, fill the gaps between the simulated reservoir units with formation sand, and connect the sealing cover plate.

[0028] After the simulated reservoir is constructed, the sand / filling / production simulation experiment can be carried out according to the experimental requirements. After the experiment, the simulated formation unit is taken out and the tie is cut off. The squeeze filling or gravel mixing form can be observed by opening it. The sand deficit form, squeeze filling form and sand-gravel mixing form after production on the horizontal section of the formation can be observed by taking out the simulated reservoir unit horizontally and opening it. The filling form and sand form of the vertical section of the formation can be observed by taking it out vertically and opening it.

[0029] The simulated reservoir unit of the present invention can flexibly adjust the thickness, length, thickness and shape to intuitively simulate different sand-producing deficit forms (large holes, honeycomb-like shapes, earthworm-like holes) and reservoirs with different physical properties (heterogeneity). After the experiment, it can be taken out longitudinally to observe the longitudinal filling and sand-producing profiles, and it is easier to observe the sand and gravel mixing form in the sand-carrying production process. The experimental process and results are more in line with field conditions.

[0030] Figures 9a to 9c Provided are photos of simulation experiments of the entire process of sand production, filling and production. Figure 9a The experimental case photos of the simulated reservoir are shown in Figure 2. Figure 9b Experimental case pictures of simulating sand production deficit in reservoir units. Fig.9c A photograph of the reservoir simulation unit being opened longitudinally after filling to observe the simulated stratigraphic section.

[0031] Furthermore, the method further comprises the following steps:

[0032] S4, simulate the production process: open the first control valve and the second control valve, close the third control valve, the fourth control valve and the fifth control valve, pump fluid into the circulation liquid inlet through the screw pump, set the screw pump speed according to the actual reservoir construction conditions, and simulate the production process.

[0033] The present invention also discloses a method for evaluating the squeezing and filling effect of a loose sandstone reservoir, and the evaluation method is for evaluating the squeezing and filling effect of step S3 in the above-mentioned full-process simulation experimental method.

[0034] After step S3 is completed, several simulated reservoir units are opened according to the experimental requirements and the squeeze filling morphology is observed. Three squeeze filling modes are proposed, namely undersaturated filling mode, saturated filling mode and oversaturated filling mode. The specific meanings are as follows: undersaturated filling ( Figure 8 As shown in a): After the filling is completed, the gravel interface (27 is the filling material in the simulated gravel layer of the present invention) and the formation sand interface (28 is the simulated formation sand of the present invention) are not in contact, the formation deficit is not fully filled, and there are obvious gaps. Saturated filling ( Figure 8 (b): After filling, the gravel interface and the formation sand interface are in obvious contact but not mixed, and there is a clear interface. Figure 8 (as shown in c): After the filling is completed, the gravel interface and the formation sand interface have been mixed and blurred, the original formation interface has been destroyed, the filling layer has poor sand retaining performance, and sand is easily produced during the production process.

[0035] The specific evaluation method includes the following steps:

[0036] (1) Calculation of undersaturated filling mode and undersaturated filling effect index

[0037] Definition of undersaturated filling effect index S q It is used to characterize the proportion of undersaturated filling mode in all filling modes, S q The larger the value is, the higher the proportion of undersaturated filling mode in all filling modes is, and the worse the filling effect is. q The following formula can be used for calculation:

[0038]

[0039] In formula (I): S q —Undersaturated filling effect index, dimensionless; n q —The number of simulated reservoir units whose filling mode is undersaturated filling mode; m qi —The mass of filling materials inside the simulated reservoir unit with the filling mode being undersaturated filling mode, g; m—The total mass of filling materials inside all simulated reservoir units in a single experiment, g.

[0040] (2) Calculation of saturated filling mode and saturated filling effect index

[0041] Definition of saturation filling effect index S b It is used to characterize the proportion of saturated filling mode in all filling modes, S b The larger the value is, the higher the proportion of saturated filling mode in all filling modes is, and the better the filling effect is. b The following formula can be used for calculation:

[0042]

[0043] In formula (II): S b —Saturated filling effect index, dimensionless; n b —The number of simulated reservoir units whose filling mode is saturated filling mode; m bi —The mass of filling materials inside the simulated reservoir unit with the filling mode being the saturated filling mode, g; m—The total mass of filling materials inside all simulated reservoir units in a single experiment, g.

[0044] (3) Calculation of supersaturated filling mode and supersaturated filling effect index

[0045] Definition of supersaturated filling effect index S g It is used to characterize the proportion of supersaturated filling mode in all filling modes, S g The larger the value is, the higher the proportion of supersaturated filling mode in all filling modes is, and the worse the filling effect is. g The following formula can be used for calculation:

[0046]

[0047] In formula (III): S g —Supersaturated filling effect index, dimensionless; n g —The number of simulated reservoir units whose filling mode is supersaturated filling mode; m gi —The mass of filling materials inside the simulated reservoir unit with the filling mode being the supersaturated filling mode, g; m—The total mass of filling materials inside all simulated reservoir units in a single experiment, g.

[0048] (4) Calculation of dense filling effect index

[0049] The dense filling effect index is defined as the ratio of the actual filling material mass to the filling material mass under the ideal dense filling state under the same displacement container and experimental conditions. It is used to characterize the filling density of the filling layer. m The larger it is, the denser the filling is and the better the filling effect is. m The following formula can be used for calculation:

[0050]

[0051] In formula (IV): S m —Dense filling effect index, dimensionless; n—the number of all simulated reservoir units used in a single experiment; m i —Mass of filling material inside a single simulated reservoir unit, g; m f —Mass of filling materials between all simulated reservoir unit gaps, g; m max —The maximum mass of filling material that can be filled under full manual compaction (to ensure that the top cover of the main device can be sealed and does not leak), which can be measured before the experiment, g.

[0052] (5) Calculation of comprehensive evaluation index of filling effect

[0053] A comprehensive evaluation index S of filling effect is proposed to characterize the overall effect of extrusion filling. The comprehensive evaluation index S of filling effect can be calculated by the following formula:

[0054] S=b·S b +d·S m +a·(1-S q )+c·(1-S g )(V)

[0055] In formula (V): S is a comprehensive evaluation index of filling effect, dimensionless; S q —Undersaturated filling effect index, dimensionless; S b —Saturated filling effect index, dimensionless; S g —Supersaturated filling effect index, dimensionless; S m —Dense filling effect index, dimensionless; a, b, c, d—correction coefficients, dimensionless.

[0056] The range of S is between 0 and 1. The larger the S is, the better the filling effect is. The recommended values ​​of the correction coefficient are: a = 0.15b = 0.2c = 0.15d = 0.5.

[0057] According to the actual working conditions in production, the filling effect requirements (i.e. the S value requirements) of the filling project are set. After simulating extrusion filling for the filling project, the filling effect is evaluated. When the S value does not meet the requirements, the filling parameters are adjusted, and the extrusion filling process is simulated and the filling effect is evaluated again until the S value meets the requirements. The pressure and flow data of the simulated extrusion filling process when the S value meets the requirements are recorded. This data is used to guide the actual extrusion filling work.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The present invention is a simulation experiment device, simulation experiment method and filling effect evaluation method for the whole process of squeezing and filling production in loose sandstone reservoirs. It can visualize and simulate different sand production and deficit forms and reservoirs with different physical properties for loose sandstone sand production and deficit reservoirs, simulate the whole process of sand production-filling-production, and realize squeezing and filling effect evaluation. Its beneficial effects specifically include:

[0060] (1) The whole-process simulation experimental device for squeezing and filling production of loose sandstone reservoirs of the present invention can carry out simulation experiments on the whole process of sand production-filling-production. The simulation function is comprehensive and conforms to the actual reservoir conditions. The main module of the experimental device can simulate strata with different sand production and deficit forms. The experimental results can effectively support on-site squeezing and filling sand prevention operations.

[0061] (2) The present invention sets a number of simulated reservoir units in the main module of the experimental device. By adjusting the internal formation sand filling morphology of the simulated reservoir units, two types of reservoirs, namely, complete reservoirs and complex sand production deficit morphologies, can be simulated. The simulated reservoir is divided into a number of independent reservoir simulation units. Each reservoir simulation unit can be flexibly adjusted in thickness, length, coarseness and shape. After the experiment, the unit can be taken out longitudinally to observe the longitudinal filling and sand production profiles. The experimental process and results are more in line with the field conditions, providing support for differentiated and refined sand control design.

[0062] (3) The whole-process simulation experimental method of the loose sandstone reservoir squeeze filling production of the present invention can not only complete the individual processes of sand production, filling and production, but also complete the whole process. The obtained experimental parameters can provide data support for the squeeze filling effect evaluation method. The squeeze filling effect evaluation method of the present invention can intuitively and quantify the effect of squeeze filling, can effectively guide the optimization of on-site squeeze filling parameters, and improve the squeeze filling sand control effect in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Schematic diagram of different sand production deficit forms in loose sandstone reservoirs;

[0064] Figure 2 This is a schematic diagram of the production process of reservoir sand production-extrusion filling-production;

[0065] Figure 3 This is a schematic diagram of the whole process simulation experimental device for extrusion filling of loose sandstone reservoirs of the present invention;

[0066] Figure 4 A schematic diagram of the main module of the experimental device of the whole process simulation experimental device for extrusion filling of loose sandstone reservoirs of the present invention;

[0067] Figure 5 Schematic diagram of the preparation of the simulation unit for the complex sand-producing deficit reservoir near the wellbore (top view);

[0068] Figure 6 Schematic diagram of the preparation of the simulation unit for the complex sand-producing deficit reservoir near the wellbore (side view);

[0069] Figure 7 Schematic diagram of different complex sand production deficit forms simulated by the reservoir simulation unit of the present invention;

[0070] Figure 8 Schematic diagrams of different filling modes of the present invention and photos of typical experimental results;

[0071] Figure 9a Experimental case photos of simulated reservoirs prepared for the present invention;

[0072] Figure 9b This is a picture of an experimental case of simulating sand production deficit in a simulated reservoir unit of the present invention;

[0073] Fig.9c A photograph of the reservoir simulation unit being opened longitudinally after filling to observe the simulated stratigraphic section.

[0074] Among them, 1-simulated reservoir mold, 2-simulated casing, 3-screen, 4-sealed cover, 5-transparent observation window, 6-circulation liquid inlet 6, 7-reservoir filling port, 8-sand adding port, 9-circulation liquid outlet, 10-liquid storage tank, 11-screw pump, 12-automatic sand adder, 13-first control valve, 14-second control valve, 15-third control valve, 16-fourth control valve, 17-fifth control valve, 18-flow sensor I, 19-flow sensor II, 20-flow sensor III, 21-flow sensor IV, 22-pressure sensor I, 23-pressure sensor II, 24-pressure sensor III, 25-pressure sensor IV, 26-simulated reservoir unit, 27-filling material, 28-simulated formation sand, 29-wellbore, 30-cap layer, 31-loose sandstone reservoir, 32-perforation hole, 33-sand deficit, 34-produced sand grains. DETAILED DESCRIPTION

[0075] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings.

[0076] Example 1

[0077] like Figure 3 to Figure 6 As shown, this embodiment is a full-process simulation experimental device for squeezing and filling of loose sandstone reservoirs, including a main module of the experimental device, a constant flow fluid supply system and a data measurement and acquisition system, and the constant flow fluid supply system and the data measurement and acquisition system are both connected to the main module of the experimental device.

[0078] The main module of the experimental device includes a simulated reservoir mold 1, a simulated casing 2, a screen 3 and a sealing cover plate 4.

[0079] The simulated reservoir mold 1 is sealed and detachably connected to the sealing cover plate 4, and a transparent observation window 5 is provided on the sealing cover plate 4. In this embodiment, the simulated reservoir mold 1 is made of steel, with a diameter of 70 cm and a height of 40 cm. The thickness of the steel base is 3 cm. The steel side wall and the detachable sealing cover plate 4 form a cylindrical tank chamber. The sealing cover plate 4 and the simulated reservoir mold 1 are tightened by eight bolts, and the mating part is sealed with a sealing ring. The transparent observation window 5 is made of acrylic material and has a fan-shaped shape. A total of 8 transparent observation windows 5 are arranged on the sealing cover plate 4 of this embodiment. A plurality of circulating liquid inlets 6 are provided on the simulated reservoir mold 1. A total of 8 circulating liquid inlets 6 are provided on the simulated reservoir mold 1 of this embodiment. The circulating liquid inlets 6 are arranged alternately on the side wall of the simulated reservoir mold 1. The aperture of the circulating liquid inlet 6 is 5 cm.

[0080] The simulation casing 2 is arranged in the middle part of the simulation reservoir mold 1, and the simulation casing 2 partially extends out of the simulation reservoir mold 1. The simulation casing 2 is provided with a sand adding port 8 and a plurality of reservoir filling ports 7. The reservoir filling port 7 is located on the inner side of the simulation reservoir mold 1, and the sand adding port 8 is located on the outer side of the simulation reservoir mold 1. The simulation casing 2 of this embodiment has a diameter of 17.8 cm, and the aperture of the reservoir filling port 7 is 12 to 14 mm. The reservoir filling port 7 is spirally distributed on the simulation casing 2.

[0081] A plurality of simulated reservoir units 26 are also provided in the simulated reservoir mold 1. The simulated reservoir units 26 are laid layer by layer around the simulated casing 2 and fill the simulated reservoir mold 1. The simulated reservoir units 26 are filled with simulated formation sand.

[0082] The screen tube 3 is arranged in the middle of the simulated casing 2 and is detachably connected to the simulated reservoir mold 1. The screen tube 3 partially extends out of the simulated reservoir mold 1. The screen tube 3 is provided with a circulating liquid outlet 9 and a plurality of liquid outlet holes (not shown in the figure). The liquid outlet holes are located inside the simulated reservoir mold 1, and the circulating liquid outlet 9 is located outside the simulated reservoir mold 1. The simulated screen tube of this embodiment has a diameter of 7.6 cm and a height of 91.2 cm. The aperture of the liquid outlet hole is 10 mm and the hole spacing is 2 cm. Sand blocking nets are provided in the circulating liquid inlet 6 and the liquid outlet hole.

[0083] The constant flow liquid supply system includes a liquid storage tank 10, a screw pump 11, and an automatic sand feeder 12 which are connected in sequence. The screw pump 11 is connected to a circulating liquid inlet 6, and a first control valve 13 is provided between the screw pump 11 and the circulating liquid inlet 6; the circulating liquid outlet 9 is connected to the liquid storage tank 10, and a second control valve 14 is provided between the circulating liquid outlet 9 and the liquid storage tank 10; the automatic sand feeder 12 is connected to a sand feeding port 8, and a third control valve 15 is provided between the automatic sand feeder 12 and the sand feeding port 8; the circulating liquid inlet 6 is connected to the liquid storage tank 10, and a fourth control valve 16 is provided between the circulating liquid inlet 6 and the liquid storage tank 10; a fifth control valve 17 is provided between the screw pump 11 and the automatic sand feeder 12.

[0084] The data measurement and acquisition system includes a flow sensor, a pressure sensor and a computer acquisition end. The computer acquisition end is connected to the flow sensor and the pressure sensor signals. The flow sensor includes a flow sensor I18, a flow sensor II19, a flow sensor III20, and a flow sensor IV21. The pressure sensor includes a pressure sensor I22, a pressure sensor II23, a pressure sensor III24, and a pressure sensor IV25. The flow sensor I18 and the pressure sensor I22 are arranged between the screw pump 11 and the circulating liquid inlet 6. The flow sensor II19 and the pressure sensor II23 are located between the circulating liquid outlet 9 and the liquid storage tank 10. The flow sensor III20 and the pressure sensor III24 are arranged between the automatic sand feeder 12 and the sand feeding port 8. The flow sensor IV21 and the pressure sensor IV25 are arranged between the circulating liquid inlet 6 and the liquid storage tank 10.

[0085] Example 2

[0086] This embodiment discloses a method for simulating the whole process of squeezing and filling a loose sandstone reservoir using the simulation experimental device of embodiment 1, comprising the following steps:

[0087] S1. Build a complete simulated reservoir:

[0088] If a reservoir sand production process simulation experiment is to be conducted, a complete formation should be simulated. At this time, the simulated reservoir unit 26 is set to a prism shape with uniform length, height and width. The filter screen is cut into a suitable size, bent into a prism shape, and fixed with a transparent white tie. At this time, the laying mode is as shown in the attached figure. Figure 5 , Attachment Figure 6 As shown. The top surface of the prism faces the simulated casing 2, and the bottom surface faces the side wall of the simulated reservoir mold 1. The simulated reservoir unit 26 is laid from the bottom of the simulated reservoir mold 1, and the inside is filled with simulated formation sand and consolidated to form a formation with a certain strength. After laying one layer, the second layer is laid, and so on, until the simulated reservoir unit 26 covers the entire simulated reservoir mold 1, and finally the gaps between the simulated reservoir units 26 are filled with formation sand and consolidated, and the simulated formation is constructed.

[0089] S2. Simulate the sand production process of the reservoir:

[0090] Open the first control valve 13 and the second control valve 14, close the third control valve 15, the fourth control valve 16 and the fifth control valve 17, pump fluid into the circulating liquid inlet 6 through the screw pump 11, and the fluid flows into the liquid storage tank through the circulating liquid outlet 9 for recycling. Set the pump speed of the screw pump according to the actual construction conditions of the reservoir, simulate the sand production process of the reservoir, and record the data of the flow sensor I18, the pressure sensor I22, the flow sensor II19, and the pressure sensor II23 during the simulated reservoir sand production process. The data recorded in step S2 is used to draw the pressure flow curve and calculate the reservoir permeability. The reservoir permeability can reflect the sand degree.

[0091] S3, simulated extrusion filling process:

[0092] Close the first control valve 13 and open the second control valve 14, open the third control valve 15, the fourth control valve 16 and the fifth control valve 17, pump the sand-carrying liquid into the sand-adding port 8 through the screw pump 11 and the automatic sand-adding pump 12 to simulate the extrusion filling process, and the fluid flows into the liquid storage tank through the circulation liquid inlet 6 for recycling. Record the data of the flow sensor III20, the pressure sensor III24, the flow sensor IV21, and the pressure sensor IV25 during the simulated extrusion filling process.

[0093] The initial screw pump speed and sand feeder pump frequency (sand ratio) during extrusion filling are mainly selected based on experience according to the relevant geological parameters of the actual reservoir, construction parameters and the degree of sand production obtained in step S2. Adjust to the set screw pump speed and sand feeder pump frequency (sand ratio) to start the experiment, and turn on the real-time data acquisition system at the same time. During the experiment, the state of extrusion filling can be monitored through the transparent observation window 5; when the pressure rises rapidly by 0.5MPa within 10 seconds, stop the pump and suspend data collection, and record the flow and pressure changes of extrusion filling. Evaluate the extrusion filling effect after data processing and analysis.

[0094] S4. Simulate production process:

[0095] Open the first control valve 13 and the second control valve 14, close the third control valve 15, the fourth control valve 16 and the fifth control valve 17, pump fluid into the circulating liquid inlet 6 through the screw pump 11, and the fluid flows into the liquid storage tank for recycling through the circulating liquid outlet 9. Set the pumping speed of the screw pump according to the actual construction conditions of the reservoir to simulate the production process.

[0096] Example 3

[0097] This embodiment discloses a full-process simulation experimental method for squeezing and filling a loose sandstone reservoir using the simulation experimental device of embodiment 1. This embodiment is a full-process simulation method for a reservoir with complex sand production and deficit forms. The difference from embodiment 2 is that:

[0098] Before step S3, the method further includes the following steps:

[0099] Construct a simulated reservoir with sand production deficit:

[0100] Take out the simulated reservoir constructed in step S1.

[0101] The sand deficit morphology obtained after sand production from the reservoir is difficult to predict and control. If you want to observe the extrusion filling morphology under different complex sand deficit morphology conditions, different sand deficit morphologies should be set manually, and it is necessary to fill the simulated reservoir unit 26 with simulated formation sand of different morphologies and different porosity and permeability properties. At this time, the simulated reservoir unit 26 can be set with different shapes, sizes, thicknesses and lengths. The filter screen is cut into a suitable size, bent into the required shape, and fixed with a transparent white cable tie. It is freely laid in the simulated reservoir mold 1 according to the experimental sand deficit morphology requirements. The simulated reservoir unit is laid from the bottom of the simulated reservoir mold 1, and the inside is filled with simulated formation sand and consolidated until the simulated reservoir unit covers the entire device. Finally, the gaps between the simulated reservoir units are filled with formation sand and consolidated. At this time, the simulated formation is constructed.

[0102] See the attached for an example of artificially set sand production deficit form. Figure 7 The sand production deficit forms are divided into large holes ( Figure 7 a), honeycomb-like ( Figure 7 Middle b), earthworm-like holes ( Figure 7 c) There are three typical forms. If the form of large-pore sand-producing deficit is to be simulated, the rule of formation sand filling inside the simulated reservoir (the whole formed by several simulated reservoir units 26) should be that there are more formation sands at the bottom and top and less formation sands in the middle; if the form of honeycomb-like sand-producing deficit is to be simulated, the rule of formation sand filling inside the simulated reservoir should be heterogeneity and the presence of a certain amount of small irregular sand-producing pores; if the form of earthworm-like sand-producing deficit is to be simulated, the rule of formation sand filling inside the simulated reservoir should be that a small part forms a long curved deficit channel, and the remaining reservoir units only produce a small amount of sand.

[0103] Example 4

[0104] This embodiment discloses a method for evaluating the effect of squeeze filling in a loose sandstone reservoir. This embodiment adopts the squeeze filling full process simulation method described in Example 2 to simulate squeeze filling:

[0105] S1. The reservoir simulated in this embodiment is a large-pore sand-producing deficit reservoir, and a total of 40 simulated reservoir units are used, 8 in each layer, and 5 layers are laid;

[0106] In S2 and S3, the screw pump speed during sand discharge simulation is 0.07m / s. 3 / min, the pressure and flow data were obtained in real time during the experiment, and the reservoir permeability was calculated to be 0.7μm after the experiment. 2 ; Actual reservoir permeability 0.71μm 2 , the displacement used during construction is 1.5m 3 / min, sand ratio 15%, based on this setting, the pump speed of S3 screw pump is 1.5m 3 / min, the pump frequency of the sand feeder is 10Hz (15% sand ratio), and the pressure recorded by S3 after filling is 0.80MPa and the flow rate is 1.5m 3 / min.

[0107] After the filling process is completed, all simulated reservoir units are opened to observe the number of various filling modes and weigh the filling materials. The result is the undersaturated filling mode reservoir unit n q = 20, the mass of the filling material inside the undersaturated filling mode reservoir unit is 35kg, and the saturated filling mode reservoir unit n b = 12, the mass of the filling material inside the saturated filling mode reservoir unit is 32kg, and the supersaturated filling mode reservoir unit n g = 8, the mass of filling materials inside the reservoir unit in the oversaturated filling mode is 28kg, the total mass of filling materials in all simulated reservoir units in the example is m = 95kg, the maximum mass of filling materials that can be filled under full artificial compaction is m max =120kg, the mass of filling materials between all simulated reservoir unit gaps m f =3.5kg. The undersaturated filling effect index S is calculated using the above experimental data. q =0.368, saturated filling effect index S b =0.337, supersaturated filling effect index S g =0.295, dense filling effect index S m =0.821, filling effect comprehensive evaluation index S = 0.678.

[0108] The larger S is, the better the filling effect is. The on-site requirement is that the comprehensive evaluation index S of the filling effect reaches 0.8 to meet the construction requirements. The example S is 0.678, which does not meet the on-site construction requirements. The filling parameters can be adjusted, and the extrusion filling process can be simulated and the filling effect can be evaluated again until the S value meets the requirements (≥0.8). The pressure and flow data recorded in the simulated extrusion filling process when the S value meets the requirements are recorded. This data is used to guide the actual extrusion filling work.

Claims

1. A full-process simulation experimental device for squeezing and filling of loose sandstone reservoirs, characterized in that: It includes the main module of the experimental device, the constant flow liquid supply system and the data measurement and acquisition system. The main module of the experimental device includes a simulated reservoir mold, a simulated casing, a screen tube and a sealing cover plate. The simulated reservoir mold is sealed and detachably connected to the sealing cover plate. A transparent observation window is provided on the sealing cover plate. The simulated reservoir mold is provided with a number of circulating liquid inlets; The simulation sleeve is arranged in the middle of the simulation reservoir mold, the simulation sleeve part extends out of the simulation reservoir mold, the simulation sleeve is provided with a sand adding port and a plurality of reservoir filling ports, the reservoir filling port is located inside the simulation reservoir mold, and the sand adding port is located outside the simulation reservoir mold; A plurality of simulated reservoir units are also arranged in the simulated reservoir mold. The simulated reservoir units are laid layer by layer around the simulated casing and fill the simulated reservoir mold. The simulated reservoir units are filled with simulated formation sand. The screen tube is arranged in the middle of the simulated casing and is detachably connected to the simulated reservoir mold. The screen tube partly extends out of the simulated reservoir mold. The screen tube is provided with a circulating liquid outlet and a plurality of liquid outlet holes. The liquid outlet holes are located inside the simulated reservoir mold, and the circulating liquid outlet is located outside the simulated reservoir mold. The circulating liquid inlet and the liquid outlet are both provided with sand blocking nets; The constant flow liquid supply system is connected with the circulating liquid inlet, circulating liquid outlet and sand adding port; The data measurement and acquisition system is connected to the main module of the experimental device.

2. The simulation experiment device according to claim 1, characterized in that: The constant flow liquid supply system comprises a liquid storage tank, a screw pump and an automatic sand feeder connected in sequence. The screw pump is connected to the circulating liquid inlet, and a first control valve is provided between the screw pump and the circulating liquid inlet; The circulating liquid outlet is connected to the liquid storage tank, and a second control valve is provided between the circulating liquid outlet and the liquid storage tank; The automatic sand feeder is connected to the sand feeding port, and a third control valve is provided between the automatic sand feeder and the sand feeding port; The circulating liquid inlet is connected to the liquid storage tank, and a fourth control valve is provided between the circulating liquid inlet and the liquid storage tank; A fifth control valve is arranged between the screw pump and the automatic sand feeder.

3. The simulation experiment device according to claim 1, characterized in that: The data measurement and acquisition system includes a flow sensor, a pressure sensor and a computer acquisition terminal, wherein the computer acquisition terminal is connected to the flow sensor and the pressure sensor signals. The flow sensor includes flow sensor I, flow sensor II, flow sensor III and flow sensor IV, and the pressure sensor includes pressure sensor I, pressure sensor II, pressure sensor III and pressure sensor IV. The flow sensor I and pressure sensor I are arranged between the screw pump and the circulating liquid inlet, the flow sensor II and pressure sensor II are located between the circulating liquid outlet and the liquid storage tank, the flow sensor III and pressure sensor III are arranged between the automatic sand feeder and the sand feeding port, and the flow sensor IV and pressure sensor IV are arranged between the circulating liquid inlet and the liquid storage tank.

4. A full-process simulation experiment method for squeezing and filling loose sandstone reservoirs using the simulation experiment device according to any one of claims 1 to 3, characterized in that: The steps include: S1. Build a complete simulated reservoir: Select a filter with a pore size smaller than the particle size of the formation sand and the particle size of the filling material, cut and bend the filter into a number of simulated reservoir units, densely fill the simulated reservoir units with simulated formation sand, and lay the simulated reservoir units layer by layer around the simulated casing in the simulated reservoir mold until the simulated reservoir units fill the simulated reservoir mold, fill the gaps between the simulated reservoir units with formation sand, and connect the sealing cover plate; S2. Simulate the sand production process of the reservoir: Open the first control valve and the second control valve, close the third control valve, the fourth control valve and the fifth control valve, pump fluid into the circulating liquid inlet through the screw pump, set the pump speed of the screw pump according to the actual construction conditions of the reservoir, simulate the sand production process of the reservoir, and record the data of the flow sensor I, the pressure sensor I, the flow sensor II, and the pressure sensor II during the simulated reservoir sand production process; S3, simulated extrusion filling process: Close the first control valve and open the second control valve, open the third control valve, the fourth control valve and the fifth control valve, set the screw pump speed and the sand feeder pump frequency, pump sand-carrying liquid into the sand feeding port through the screw pump and the automatic sand feeding pump to simulate the extrusion filling process. During the experiment, monitor the state of extrusion filling through a transparent observation window. When the pressure rises by 0.5 MPa within 10 seconds, close the screw pump and record the data of flow sensor III, pressure sensor III, flow sensor IV, and pressure sensor IV during the simulated extrusion filling process.

5. A full-process simulation experimental method according to claim 4, characterized in that: The following steps are also included: S4. Simulate production process: Open the first control valve and the second control valve, close the third control valve, the fourth control valve and the fifth control valve, pump fluid into the circulating liquid inlet through the screw pump, set the screw pump speed according to the actual reservoir construction conditions, and simulate the production process.

6. A full-process simulation experimental method according to claim 4, characterized in that: Before step S3, the method further includes the following steps: Construct a simulated reservoir with sand production deficit: Take out the simulated reservoir constructed in step S1, select a filter with a pore size smaller than the particle size of the formation sand and the particle size of the filling material, cut and bend the filter into several simulated reservoir units, and partially fill the simulated reservoir units with simulated formation sand according to the form of the sand deficit. Arrange and combine them in the simulated reservoir mold according to the requirements of different deficit formation forms until the simulated reservoir units cover the simulated reservoir mold, fill the gaps between the simulated reservoir units with formation sand, and connect the sealing cover plate.

7. A method for evaluating the effect of squeezing and filling in loose sandstone reservoirs using the full-process simulation experimental method according to any one of claims 4 to 6, characterized in that: The steps include: (1) Calculation of undersaturated filling mode and undersaturated filling effect index In formula (I): S q is the undersaturated filling effect index, dimensionless; n q is the number of simulated reservoir units with undersaturated filling mode; m qi is the mass of filling materials inside the simulated reservoir unit with undersaturated filling mode, g; m is the total mass of filling materials inside all simulated reservoir units in a single experiment, g; (2) Calculation of saturated filling mode and saturated filling effect index In formula (II): S b is the saturated filling effect index, dimensionless; n b is the number of simulated reservoir units with saturated filling mode; m bi is the mass of filling material inside the simulated reservoir unit with saturated filling mode, g; (3) Calculation of supersaturated filling mode and supersaturated filling effect index In formula (III): S g is the supersaturated filling effect index, dimensionless; n g is the number of simulated reservoir units with supersaturated filling mode; m gi is the mass of filling material inside the simulated reservoir unit with the filling mode being the supersaturated filling mode, g; (4) Calculation of dense filling effect index In formula (IV): S m is the dense filling effect index, dimensionless; n is the number of all simulated reservoir units used in a single experiment; m i is the mass of filling material inside a single simulated reservoir unit, g; m f is the mass of filling materials between all simulated reservoir unit gaps, g; m max is the maximum filling material mass, g; (5) Calculation of comprehensive evaluation index of filling effect S=b·S b +d·S m +a·(1-S q )+c·(1-S g )(V) In formula (V), S is a comprehensive evaluation index of filling effect, dimensionless; a, b, c, d are correction coefficients, dimensionless.

8. The filling effect evaluation method according to claim 7, characterized in that: a=0.15b=0.2c=0.15d=0.5.

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