An experimental device for full-process simulation of squeeze packing in unconsolidated sandstone reservoirs, a full-process simulation experimental method, and a method for evaluating packing effect

Abstract

The present invention belongs to the technical field of oil and gas development and production engineering, and specifically relates to a full-process simulation experimental device for squeeze packing of unconsolidated sandstone reservoirs, a full-process simulation experimental method, and a filling effect evaluation method. The full-process simulation experimental device includes an experimental device main body module, a constant flow liquid supply system, and a data measurement and acquisition system. The experimental device main body module includes a simulated reservoir mold, a simulated casing, a screen pipe, and a sealing cover plate. The simulated reservoir mold is sealed and detachably connected to the sealing cover plate. A number of simulated reservoir units are also provided in the simulated reservoir mold. The simulated reservoir units are laid layer by layer around the simulated casing and filled in the simulated reservoir mold. The simulated reservoir units are filled with simulated formation sand. The constant flow liquid supply system and the data measurement and acquisition system are connected to the experimental main body device. The simulation experimental device of the present invention can realize the full-process simulation of sand production - filling - production, and the filling effect evaluation method can provide theoretical guidance for the optimization of squeeze packing parameters at the construction site.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas development and production engineering, and particularly relates to a full-process simulation experiment device for squeeze filling of loose sandstone reservoirs, a full-process simulation experiment method, and a filling effect evaluation method. Background Art

[0002] Loose sandstone reservoirs are widely distributed in China, and their efficient development is of great significance for ensuring national energy security. There are serious sand production problems in loose sandstone reservoirs. Especially after multiple rounds of sand production prevention and control, sand production deficits of different forms will appear in the near-well reservoir. The sand production deficit refers to the continuous production of formation sand grains from the formation, which will inevitably leave pores in the formation. After serious or long-term sand production, deficits will be formed due to sand production. The deficit forms are relatively complex, seriously restricting the sand control effect. According to the historical fitting of sand production deficits in old wells, the sand production deficit forms are roughly divided into three typical forms: large holes ( Figure 1 as shown in a in Figure 1 ), honeycomb-like ( Figure 1 as shown in b in Figure 1 ), and earthworm hole-like ( Figure 1 as shown in c in Figure 1 ).

[0003] Extrusion packing sand control refers to using a sand-carrying fluid to carry and inject quartz sand or artificial ceramic particles into the formation at a certain mixing ratio. These solid particles will fill the sand production void area, form a gravel packing layer, play a role in blocking formation sand production, and at the same time maintain fluidity and productivity. The extrusion packing sand control technology injects gravel particles into the formation outside the casing in a high-pressure extrusion manner, which can form a high-permeability layer in the formation outside the pipe. Compared with gravel packing inside the pipe, it can greatly reduce the skin factor, and even form a negative skin. For sand production wells with long-term production, a large sand production void is formed in the near-well reservoir. Using the extrusion packing sand control technology, the thickness of the sand control layer formed is relatively large, and the comprehensive sand control effect is good. Due to its good sand control effect, the extrusion packing sand control technology is widely used at home and abroad. Because the actual reservoir conditions of unconsolidated sandstone are complex, it is difficult to fully consider the differences in reservoir thickness, porosity and permeability, sand production void and morphology during the extrusion packing construction process. The parameter design is still mainly based on experience, and it is still difficult to achieve refined and differentiated construction design. Moreover, there is currently no mature method for evaluating the construction effect of extrusion packing. To complete the above-mentioned full-process simulation of extrusion packing and evaluation of packing effect, indoor experimental simulation is essential, and it is also an effective and intuitive means.

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

[0005] (1) At present, the understanding of the filling process and the morphology of the filling layer in the near-well area during extrusion packing operations is still unclear. The existing experimental devices are difficult to realize the full-process simulation from sand production caused by long-term reservoir production ( Figure 2 in which 34 are the produced sand grains), to extrusion packing sand control operations, and then to continued production after sand control (as shown in Figure 2 the figure, Figure 2 in which a to c are the sand production process of the reservoir, the extrusion packing process, and the production process after production respectively), and it is difficult to simulate complex sand production void patterns, which restricts the design of on-site sand control operations and the sand control effect.

[0006] (2) For old wells with long-term production, the pore permeability difference and heterogeneity in the near-well formation are relatively strong, and the sand production process is long. The sand production void pattern is complex and difficult to predict. Most of the existing formation simulation methods are to uniformly fill sand and lay it in a container. The void pattern and observation method are single, and it is impossible to flexibly simulate different complex sand production void patterns. Moreover, it is difficult to observe the longitudinal filling and sand production profile after the experiment, and it is difficult to optimize the refined and differentiated extrusion packing construction parameters.

[0007] (3) During the extrusion packing construction operation, when the construction pressure suddenly rises to a certain value, the on-site personnel immediately judge that the filling process is over without analyzing its actual filling effect. At present, there is a lack of a simple, fast and accurate experimental evaluation method for evaluating the extrusion packing effect, resulting in inaccurate judgment on when the extrusion packing operation ends on site, which restricts the oil well production and economic benefits after production. Summary of the Invention

[0008] To solve the drawbacks of the above-mentioned prior art, the present invention discloses a full-process simulation experimental device for squeeze packing of unconsolidated sandstone reservoirs, a full-process simulation experimental method, and a filling effect evaluation method. It can visually simulate different sand production deficit forms and reservoirs with different physical properties for unconsolidated sandstone sand production and deficit reservoirs, conduct a full-process simulation of sand production - filling - production, and achieve an evaluation of the squeeze packing effect, providing key support for optimizing the squeeze packing process parameters and improving the filling effect.

[0009] Specific technical means are as follows:

[0010] A full-process simulation experimental device for squeeze packing of unconsolidated sandstone reservoirs includes an experimental device main body module, a constant-flow liquid supply system, and a data measurement and acquisition system. The experimental device main body module, as the core module, is mainly used to simulate various deficit forms and non-deficit forms of unconsolidated sandstone reservoirs and achieve indoor visual simulation of the full process of squeeze packing of unconsolidated sandstone reservoirs. The constant-flow liquid supply system, as an auxiliary module, is mainly used to provide liquid or sand-carrying fluid for the experimental device main body module and form a cycle. The data measurement and acquisition system is used for dynamic data acquisition and recording during the experiment.

[0011] The experimental device main body module includes a simulated reservoir mold, a simulated casing, a screen pipe, and a sealing cover plate. The simulated reservoir mold is hermetically and detachably connected to the sealing cover plate. The sealing cover plate is provided with a transparent observation window, which can realize visual simulation of the sand production, squeeze packing, or production process of the reservoir. The simulated reservoir mold is provided with a number of circulating liquid inlet ports; the simulated casing is arranged in the middle of the simulated reservoir mold, and a part of the simulated casing extends out of the simulated reservoir mold. The simulated casing is provided with a sand addition port and a number of reservoir filling ports. The reservoir filling ports are located inside the simulated reservoir mold, and the sand addition port is located outside the simulated reservoir mold; a number 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 filled in the simulated reservoir mold. The simulated reservoir units are filled with simulated formation sand; the screen pipe is arranged in the middle of the simulated casing and is detachably connected to the simulated reservoir mold, and can be easily replaced with other types of screen pipes. A part of the screen pipe extends out of the simulated reservoir mold. The screen pipe is provided with a circulating liquid outlet and a number 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; anti-sand meshes are arranged in both the circulating liquid inlet ports and the liquid outlet holes;

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

[0013] Further, the constant-current liquid supply system includes a liquid storage tank, a screw pump, and an automatic sand adder connected in sequence. The liquid storage tank can be a stainless-steel vertical stirred liquid storage tank with an effective volume of up to 1000 L, which has the function of stirring or storing experimental fluids. 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 adder mainly consists of a pressure-resistant sand loading cylinder, a servo motor, a conveying auger, a sand conveying cylinder body, and a liquid inlet and outlet. In the experiment, the flowing fluid can flow out after being mixed with sand, and the water flow rate meets 10 - 20 tons per hour. The liquid storage tank, the screw pump, and the automatic sand adder 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 adder is connected to the sand adding port, and a third control valve is provided between the automatic sand adder and the sand adding 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 adder.

[0015] Further, the data measurement and acquisition system includes a flow sensor, a pressure sensor, and a computer acquisition terminal. The computer acquisition terminal is signal-connected to the flow sensor and the pressure sensor.

[0016] The flow sensor includes Flow Sensor I, Flow Sensor II, Flow Sensor III, and Flow Sensor IV. The pressure sensor includes Pressure Sensor I, Pressure Sensor II, Pressure Sensor III, and Pressure Sensor IV. Flow Sensor I and Pressure Sensor I are arranged between the screw pump and the circulating liquid inlet. Flow Sensor II and Pressure Sensor II are located between the circulating liquid outlet and the liquid storage tank. Flow Sensor III and Pressure Sensor III are arranged between the automatic sand adder and the sand adding port. 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 squeeze packing of loose sandstone reservoirs using the simulation experiment device described in any one of the above, including the following steps:

[0018] S1. Construct a complete simulated reservoir:

[0019] Select a filter screen with a pore size smaller than the formation sand particle size and the filling material particle size to prevent the formation sand and the filling material from flowing between the simulated reservoir units, so that each simulated reservoir unit is independent and does not affect each other. For example, if the median particle size of the formation sand used in the experiment is 0.15 mm and the particle size of the filling material is 0.4 - 0.8 mm, then the selected filter screen size should be less than 0.15 mm. At the same time, it is required that the strength of the filter screen should meet the requirement that the filter screen at the bottom layer is not crushed after the entire simulated reservoir mold is filled. The strength of the filter screen is reflected by the filter screen thickness, that is, the wire diameter of the filter screen, and usually the wire diameter of the filter screen is required to be greater than 0.25 mm.

[0020] Cut and bend the filter screen into several simulated reservoir units. At this time, the simulated reservoir units can be set as frustum-shaped with the same length, height, and width. Densely fill the simulated formation sand in the simulated reservoir units, and lay the simulated reservoir units around the simulated casing layer by layer in the simulated reservoir mold until the simulated reservoir mold is filled with simulated reservoir units. Fill the formation sand in the gaps between the simulated reservoir units and connect the sealing cover plate; in the present invention, the simulated reservoir is divided into several independent simulated reservoir units, and each simulated reservoir unit can independently fill and consolidate the formation sand and be opened to observe the filling morphology.

[0021] S2. Simulated 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 circulating liquid inlet through the screw pump, set the screw pump speed according to the construction conditions of the actual reservoir, 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 deficit characteristics, you can open the simulated reservoir unit after the simulated reservoir sand production experiment, observe it, and then put it back into the simulated reservoir mold as it is for the 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 addition pump frequency, pump the sand-carrying fluid into the sand addition port through the screw pump and the automatic sand addition pump, simulate the extrusion filling process. During the experiment, the extrusion filling state can be monitored through the transparent observation window. When the pressure rapidly rises by 0.5 MPa within 10 seconds, stop the pump and suspend data acquisition, and record the data of flow sensor III, pressure sensor III, flow sensor IV, and pressure sensor IV during the simulated extrusion filling process. After data processing and analysis, evaluate the extrusion filling effect.

[0024] The pump speed of the screw pump and the pump frequency of the sand injector during squeeze packing are mainly selected empirically based on 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 plot the pressure-flow curve and calculate the reservoir permeability, and the sand production degree can be reflected by the reservoir permeability.

[0025] In addition, if it is necessary to observe the squeeze packing morphology under different complex sand production and voidage morphologies, different sand production and voidage morphologies should be set manually. It is necessary to fill the simulated formation sand with different morphologies and different pore permeability physical properties inside the simulated reservoir unit. 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 and voidage:

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

[0028] After the simulated reservoir is constructed, the sand production / filling / production simulation experiment can be carried out according to the experimental requirements. After the experiment is completed, take out the simulated formation unit and cut the cable tie, and open it to observe the squeeze packing or gravel mixing morphology. Take out the simulated reservoir unit horizontally and open it to observe the sand production and voidage morphology, squeeze packing morphology, and gravel mixing morphology after production on the horizontal section of the formation. Take out and open it longitudinally to observe the filling morphology and sand production morphology on the longitudinal section of the formation.

[0029] The simulated reservoir unit of the present invention can flexibly adjust the thickness, length, thickness, and shape to intuitively simulate different sand production and voidage morphologies (large holes, honeycomb-like, earthworm-like holes) and different physical properties (heterogeneity) of the reservoir. After the experiment is completed, taking it out longitudinally can observe the longitudinal filling and sand production profiles, and it is easier to observe the gravel mixing morphology during the sand-carrying production process. The experimental process and results are more in line with the on-site conditions.

[0030] Figures 9a to 9c Pictures of the full-process simulation experiment case of sand production - filling - production are given. Figure 9a For the experimental case pictures of the simulated reservoir, Figure 9b For the experimental case pictures of the simulated reservoir unit simulating sand production and voidage, Figure 9c For the picture of observing the simulated formation profile after filling and opening the reservoir simulation unit longitudinally.

[0031] Further, the following steps are also included:

[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 circulating liquid inlet through the screw pump, set the pump speed of the screw pump according to the actual reservoir construction conditions, and simulate the production process.

[0033] The present invention also discloses an evaluation method for the extrusion filling effect of loose sandstone reservoirs. This evaluation method evaluates the extrusion filling effect in step S3 of the above full-process simulation experiment method.

[0034] After step S3 is completed, open several simulated reservoir units according to the experimental requirements and observe the extrusion filling morphology. Three extrusion filling modes are proposed, namely the under-saturated filling mode, the saturated filling mode and the over-saturated filling mode. The specific meanings are as follows: Under-saturated filling ( Figure 8 as shown in a): After filling, the interface between the gravel interface (27 is the filling material in the simulated gravel layer in the present invention) and the formation sand (28 is the simulated formation sand in the present invention) is not in contact, the formation void is not fully filled, and there are obvious voids. Saturated filling ( Figure 8 as shown in b): After filling, the gravel interface and the formation sand interface are in obvious contact but not mixed, and there is an obvious interface. Over-saturated filling ( Figure 8 as shown in c): After filling, the gravel interface and the formation sand interface are mixed and blurred, the original formation interface is damaged, the sand control performance of the filling layer is poor, and sand production is likely to occur during the production process.

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

[0036] (1) Calculate the under-saturated filling mode and the under-saturated filling effect index

[0037] Define the under-saturated filling effect index S q to represent the proportion of the under-saturated filling mode in all filling modes. The larger S q , the higher the proportion of the under-saturated filling mode in all filling modes, and the worse the filling effect. S q can be calculated by the following formula:

[0038]

[0039] In formula (I): S q —Under-saturated filling effect index, dimensionless; n q —The number of simulated reservoir units with the filling mode of under-saturated filling mode; m qi —The mass of the filling material inside the simulated reservoir unit with the filling mode of under-saturated filling mode, g; m—The total mass of the filling material in all simulated reservoir units in a single experiment, g.

[0040] (2) Calculate the saturated filling mode and the saturated filling effect index

[0041] Define the saturated filling effect index S b Used to characterize the proportion of the saturated filling mode among all filling modes. The larger S b is, the higher the proportion of the saturated filling mode in all filling modes, and the better the filling effect. S b It can be calculated by the following formula:

[0042]

[0043] In formula (II): S b —Saturated filling effect index, dimensionless; n b —Number of simulated reservoir units with the filling mode of saturated filling mode; m bi —Mass of the filling material inside the simulated reservoir unit with the filling mode of saturated filling mode, g; m—Total mass of the filling material in all simulated reservoir units in a single experiment, g.

[0044] (3) Calculate the supersaturated filling mode and the supersaturated filling effect index

[0045] Define the supersaturated filling effect index S g Used to characterize the proportion of the supersaturated filling mode among all filling modes. The larger S g is, the higher the proportion of the supersaturated filling mode in all filling modes, and the worse the filling effect. S g It can be calculated by the following formula:

[0046]

[0047] In formula (III): S g —Supersaturated filling effect index, dimensionless; n g —Number of simulated reservoir units with the filling mode of supersaturated filling mode; m gi —Mass of the filling material inside the simulated reservoir unit with the filling mode of supersaturated filling mode, g; m—Total mass of the filling material in all simulated reservoir units in a single experiment, g.

[0048] (4) Calculate the dense filling effect index

[0049] The dense filling effect index is defined as the ratio of the mass of the actually filled filling material to the mass of the filling material in the ideal dense filling state under the same displacement container and experimental conditions, used to characterize the filling density of the filling layer, S m The larger S m is, the denser the filling, and the better the filling effect. S

[0050]

[0051] In formula (IV): S m — Index of dense filling effect, dimensionless; n — 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 material between the gaps of all simulated reservoir units, g; m max — Maximum mass of filling material that can be filled under full manual compaction (ensuring that the top cover of the main device can be sealed without leakage), which can be measured before the experiment, g.

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

[0053] Propose a comprehensive evaluation index S of filling effect to characterize the overall effect of squeeze 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 — Comprehensive evaluation index of filling effect, dimensionless; S q — Index of under-saturated filling effect, dimensionless; S b — Index of saturated filling effect, dimensionless; S g — Index of over-saturated filling effect, dimensionless; S m — Index of dense filling effect, dimensionless; a, b, c, d — Correction coefficients, dimensionless.

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

[0057] Set the requirement for the filling effect of this filling project (i.e., the requirement for the S value) according to the working conditions in actual production. After performing simulated squeeze filling for this filling project, evaluate the filling effect. When the S value does not meet the requirement, adjust the parameters during filling and re-perform the simulation of the squeeze filling process and the evaluation of the filling effect until the S value meets the requirement. Record the pressure and flow rate data recorded in the simulated squeeze filling process when the S value meets the requirement. This data is used to guide the actual squeeze filling work.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] The present invention relates to a simulation experiment device, a simulation experiment method, and a filling effect evaluation method for the entire process of squeeze filling production in unconsolidated sandstone reservoirs. It can visually simulate different sand production and voidage patterns and reservoirs with different physical properties for unconsolidated sandstone reservoirs with sand production and voidage, conduct a full process simulation of sand production - filling - production, and achieve an evaluation of the squeeze filling effect. The specific beneficial effects include:

[0060] (1) The simulation experiment device for the entire process of squeeze filling production in unconsolidated sandstone reservoirs of the present invention can conduct a full process simulation experiment of sand production - filling - production. The simulation function is comprehensive and conforms to actual reservoir conditions. The internal main module of the experimental device can simulate formations with different sand production and voidage patterns, and the experimental results can effectively support on-site squeeze filling sand control operations.

[0061] (2) By setting a number of simulated reservoir units in the main module of the experimental device, the present invention can simulate two types of reservoirs, namely, a complete reservoir and a complex sand production and voidage pattern, by adjusting the internal formation sand filling pattern of the simulated reservoir units. The simulated reservoir is divided into several independent reservoir simulation units, and the thickness, length, thickness, and shape of each reservoir simulation unit can be flexibly adjusted. After the experiment, it can be taken out longitudinally to observe the longitudinal filling and sand production profiles. The experimental process and results are more in line with on-site conditions, providing support for differential and refined sand control design.

[0062] (3) The simulation experiment method for the entire process of squeeze filling production in unconsolidated sandstone reservoirs of the present invention can not only complete a single process among sand production, filling, and production, but also complete the entire process of the complete technological 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 quantitatively evaluate the squeeze filling effect, effectively guide the optimization of on-site squeeze filling parameters, and improve the squeeze filling sand control effect in actual production. Description of the Drawings

[0063] Figure 1 Schematic diagrams of different sand production and voidage patterns in unconsolidated sandstone reservoirs;

[0064] Figure 2 Schematic diagram of the production process of reservoir sand production - squeeze filling - production start-up;

[0065] Figure 3 Schematic diagram of the simulation experiment device for the entire process of squeeze filling in unconsolidated sandstone reservoirs of the present invention;

[0066] Figure 4 Schematic diagram of the main module of the experimental device for the entire process of squeeze filling in unconsolidated sandstone reservoirs of the present invention;

[0067] Figure 5 Schematic diagram of the preparation and laying of the simulation unit for a near-well complex sand production and voidage reservoir (top view);

[0068] Figure 6 Prepare a layout schematic diagram (side view) for the near-wellbore complex sand production and void reservoir simulation unit;

[0069] Figure 7 Schematic diagrams of different complex sand production and void patterns 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 Photos of experimental cases of the simulated reservoir prepared by the present invention;

[0072] Figure 9b Pictures of experimental cases of sand production and void simulation by the simulated reservoir unit of the present invention;

[0073] Figure 9c Photos of the simulated formation profile observed by longitudinally opening the reservoir simulation unit after filling.

[0074] Among them, 1 - simulated reservoir mold, 2 - simulated casing, 3 - screen pipe, 4 - sealing cover plate, 5 - transparent observation window, 6 - circulating liquid inlet 6, 7 - reservoir filling port, 8 - sand addition port, 9 - circulating 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 - caprock, 31 - unconsolidated sandstone reservoir, 32 - perforation holes, 33 - sand production void, 34 - produced sand grains. Detailed implementation manners

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

[0076] Embodiment 1

[0077] As Figures 3 to 6 shown, a simulation experimental device for the whole process of extrusion filling of an unconsolidated sandstone reservoir in this embodiment includes an experimental device main body module, a constant flow liquid supply system, and a data measurement and acquisition system. The constant flow liquid supply system and the data measurement and acquisition system are both connected to the experimental device main body module.

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

[0079] The simulated reservoir mold 1 is hermetically and detachably connected to the sealing cover plate 4. 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 chamber. The sealing cover plate 4 and the simulated reservoir mold 1 are clamped by eight bolts, and the mating part is sealed with a sealing ring. The transparent observation window 5 is made of acrylic and is in the shape of a sector. A total of 8 transparent observation windows 5 are provided on the sealing cover plate 4 in this embodiment. A number of circulating liquid inlet ports 6 are provided on the simulated reservoir mold 1. A total of 8 circulating liquid inlet ports 6 are provided on the simulated reservoir mold 1 in this embodiment. The circulating liquid inlet ports 6 are arranged staggered on the side wall of the simulated reservoir mold 1. The aperture of the circulating liquid inlet port 6 is 5 cm.

[0080] The simulated casing 2 is arranged in the middle of the simulated reservoir mold 1. The simulated casing 2 extends out of the simulated reservoir mold 1 partially. A sand adding port 8 and a number of reservoir filling ports 7 are provided on the simulated casing 2. The reservoir filling ports 7 are located inside the simulated reservoir mold 1, and the sand adding port 8 is located outside the simulated reservoir mold 1. The diameter of the simulated casing 2 in this embodiment is 17.8 cm. The aperture of the reservoir filling port 7 is 12 - 14 mm. The reservoir filling ports 7 are spirally distributed on the simulated casing 2.

[0081] A number 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 inside of the simulated reservoir mold 1. The simulated reservoir units 26 are filled with simulated formation sand.

[0082] The screen pipe 3 is arranged in the middle of the simulated casing 2 and is detachably connected to the simulated reservoir mold 1. The screen pipe 3 extends out of the simulated reservoir mold 1 partially. A circulating liquid outlet 9 and a number of liquid outlet holes (not shown in the figure) are provided on the screen pipe 3. 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 diameter of the simulated screen pipe in this embodiment is 7.6 cm and the height is 91.2 cm. The aperture of the liquid outlet hole is 10 mm, and the hole pitch is 2 cm. A sand blocking net is provided in both the circulating liquid inlet port 6 and the liquid outlet hole.

[0083] The constant current liquid supply system includes a liquid storage tank 10, a screw pump 11, and an automatic sand adder 12 connected in sequence. The screw pump 11 is connected to the 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 adder 12 is connected to the sand adding port 8, and a third control valve 15 is provided between the automatic sand adder 12 and the sand adding 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 adder 12.

[0084] The data measurement and acquisition system includes a flow sensor, a pressure sensor, and a computer acquisition terminal. The computer acquisition terminal is signal-connected to the flow sensor and the pressure sensor. The flow sensor includes a flow sensor I 18, a flow sensor II 19, a flow sensor III 20, and a flow sensor Ⅳ 21. The pressure sensor includes a pressure sensor I 22, a pressure sensor II 23, a pressure sensor III 24, and a pressure sensor Ⅳ 25. The flow sensor I 18 and the pressure sensor I 22 are provided between the screw pump 11 and the circulating liquid inlet 6. The flow sensor II 19 and the pressure sensor II 23 are located between the circulating liquid outlet 9 and the liquid storage tank 10. The flow sensor III 20 and the pressure sensor III 24 are provided between the automatic sand adder 12 and the sand adding port 8. The flow sensor Ⅳ 21 and the pressure sensor Ⅳ 25 are provided between the circulating liquid inlet 6 and the liquid storage tank 10.

[0085] Embodiment 2

[0086] This embodiment discloses a full-process simulation method for squeeze packing of unconsolidated sandstone reservoirs using the simulation experiment device of Embodiment 1, including the following steps:

[0087] S1. Construct a complete simulated reservoir:

[0088] If a sand production process simulation experiment of the reservoir is to be carried out, a complete formation should be simulated. At this time, the simulated reservoir unit 26 is set as a frustum shape with the same length, height, and width. Cut the filter screen into an appropriate size, bend it into a frustum shape, and fix it with a transparent white cable tie. At this time, the laying mode is as shown in Appendix Figure 5 and Appendix Figure 6 shown. The upper surface of the frustum faces the simulated casing 2, and the lower surface faces the side wall of the simulated reservoir mold 1. Start laying the simulated reservoir unit 26 from the bottom of the simulated reservoir mold 1, fill the inside with simulated formation sand and consolidate it to form a formation with a certain strength. After laying one layer, continue to lay the second layer, and so on, until the simulated reservoir unit 26 fills the entire simulated reservoir mold 1. Finally, fill the gaps between the simulated reservoir units 26 with formation sand and consolidate it. At this time, 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 simulation of the sand production process of the reservoir. The data recorded in step S2 is used to draw the pressure-flow curve and calculate the reservoir permeability, and the degree of sand production can be reflected through the reservoir permeability.

[0091] S3. Simulate the squeeze packing 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 fluid into the sand addition port 8 through the screw pump 11 and the automatic sand addition pump 12, simulate the squeeze packing process, and the fluid flows into the liquid storage tank through the circulating 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 simulation of the squeeze packing process.

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

[0094] S4. Simulate the 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 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 to simulate the production process.

[0096] Example 3

[0097] This embodiment discloses a full - process simulation experiment method for squeeze - packing in unconsolidated sandstone reservoirs using the simulation experiment device of Embodiment 1. This embodiment is a full - process simulation method for reservoirs with complex sand - production voidage patterns, and the difference from Embodiment 2 is as follows:

[0098] Before step S3, the following steps are further included:

[0099] Construct a simulated reservoir with sand - production voidage:

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

[0101] The sand - production voidage pattern obtained after reservoir sand production is difficult to predict and control. If we want to observe the squeeze - packing pattern under different complex sand - production voidage patterns, we should artificially set different sand - production voidage patterns. We need to fill the inside of the simulated reservoir unit 26 with simulated formation sand of different patterns, pore - permeability physical properties. At this time, the simulated reservoir unit 26 can be set with different shapes, sizes, thicknesses and lengths. Cut the filter screen into an appropriate size, bend it into the required shape, fix it with transparent white cable ties, and freely lay it in the simulated reservoir mold 1 according to the experimental sand - production voidage pattern requirements. Start laying the simulated reservoir unit from the bottom of the simulated reservoir mold 1, fill the inside with simulated formation sand and consolidate it until the simulated reservoir unit covers the entire device. Finally, fill the gaps between the simulated reservoir units with formation sand and consolidate it. At this time, the simulated formation is constructed.

[0102] Examples of artificially setting sand - production voidage patterns are shown in the appendix Figure 7 . The sand - production voidage patterns are divided into three typical patterns: large holes ( Figure 7 as shown in a)), honeycomb - like ( Figure 7 as shown in b)), and earthworm - hole - like ( Figure 7 as shown in c)). If we want to simulate the large - hole sand - production voidage pattern, the rule of filling formation sand inside the simulated reservoir (the whole formed by several simulated reservoir units 26) should be that there is more formation sand at the bottom and top, and less in the middle; if we want to simulate the honeycomb - like sand - production voidage pattern, the rule of filling formation sand inside the simulated reservoir should be heterogeneity and there are a certain number of small irregular sand - production holes; if we want to simulate the earthworm - hole - like sand - production voidage pattern, the rule of filling formation sand inside the simulated reservoir should be that a small part forms long - strip - shaped curved voidage channels, and only a small amount of sand production occurs in the remaining reservoir units.

[0103] Embodiment 4

[0104] This embodiment discloses a method for evaluating the squeeze - packing effect of unconsolidated sandstone reservoirs. This embodiment uses the squeeze - packing full - process simulation method described in Embodiment 2 to conduct simulated squeeze - packing:

[0105] S1. The reservoir simulated in this embodiment is a reservoir with a large - hole sand - production voidage pattern. A total of 40 simulated reservoir units are used, 8 in each layer, and 5 layers are laid;

[0106] In S2 and S3, during sand production simulation, the pump speed of the progressing cavity pump is 0.07 m 3 / min. During the experiment, pressure and flow rate data are obtained in real time. After the experiment, the reservoir permeability is calculated to be 0.7 μm 2 ; the actual reservoir permeability is 0.71 μm 2 , and during construction, the displacement is 1.5 m 3 / min and the sand ratio is 15%. Based on this, the pump speed of the progressing cavity pump in S3 is set to 1.5 m 3 / min, the pump frequency of the sand injector is 10 Hz (15% sand ratio). After filling, the pressure recorded at the end of filling in S3 is 0.80 MPa and the flow rate is 1.5 m 3 / min.

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

[0108] The larger the S value, the better the filling effect. The on-site requirement is that the comprehensive evaluation index S of the filling effect reaches 0.8 to meet the construction requirements. In the example, S is 0.678, which does not meet the on-site construction requirements. The parameters during filling can be adjusted, and the simulation of the extrusion filling process and the evaluation of the filling effect can be carried out again until the S value meets the requirements (≥0.8). Record the pressure and flow rate data recorded in the simulated extrusion filling process when the S value meets the requirements. 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; 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 provided between the screw pump and the automatic sand feeder; 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.

2. A method for simulating the whole process of squeezing and filling a loose sandstone reservoir using the whole process simulation experimental device for squeezing and filling a loose sandstone reservoir according to claim 1, 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 pump speed of the screw pump and the pump frequency of the sand feeder, and 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 the extrusion filling is monitored through the transparent observation window. When the pressure rises by 0.5MPa within 10 seconds, close the screw pump, and record the data of the flow sensor III, the pressure sensor III, the flow sensor IV, and the pressure sensor IV during the simulated extrusion filling process; 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.

3. The full-process simulation experiment method according to claim 2 is 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.

4. A method for evaluating the filling effect of a loose sandstone reservoir squeeze filling based on the full-process simulation experimental method of a loose sandstone reservoir squeeze filling according to any one of claims 2 to 3, characterized in that: The steps include: (1) Calculation of undersaturated filling mode and undersaturated filling effect index （I） 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 (II) 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 (III) 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 (IV) 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 （V） In formula (V), S is the comprehensive evaluation index of filling effect, dimensionless; a, b, c, d are correction coefficients, dimensionless.

5. The filling effect evaluation method according to claim 4, characterized in that: a=0.15, b=0.2, c=0.15, d=0.5.

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