Experimental device and method for distribution pattern of interwell dominant channel in steam flooding of heavy oil reservoir

Abstract

The present application relates to a kind of thick oil reservoir steam flooding well interchannel advantage passage distribution form experimental device and method, method includes: setting steam flooding advantage passage, selecting particle filling the reservoir model, in the reservoir model is installed multiple well with multiple-point method, and temperature measuring point and pressure measuring point are arranged according to appropriate distance;The pore volume of the reservoir model is calculated, porosity, initial condition temperature field, oil saturation field are established;The injection system, the measurement and control system are opened, set flow, open the steam generator, set temperature and adjust steam dryness;According to the related parameters of experimental scheme design three-dimensional similarity criterion, simulate steam flooding oil process, continue steam injection to injection well, collect produced fluid and make experimental record;When steam flooding to instantaneous oil vapor ratio is less than 0.1, end displacement, interwell generates stable advantage passage, inject glue, after solidification, open the reservoir model, remove advantage passage skeleton, quantize morphological characteristics and scale size.

Description

Technical Field

[0001] This invention relates to an experimental apparatus and method for the distribution pattern of dominant channels between steam-driven wells in heavy oil reservoirs, belonging to the field of oil and gas extraction technology. Background Technology

[0002] Steam flooding is an important technology for heavy oil thermal recovery. However, due to the over-coverage of steam, steam flooding often results in low recovery rates and high residual oil saturation in the formation. Furthermore, geological differences among different reservoirs lead to varying steam flooding characteristics. Although numerous three-dimensional experiments have studied steam flooding development parameters, few experiments have quantitatively described the heat transfer patterns of the three-dimensional models. The understanding of the temperature expansion characteristics of the steam chamber during steam flooding, as well as the seepage mechanisms and oil displacement patterns at different development stages, remains unclear. Moreover, no research has been found on the follow-up methods for steam flooding in the later stages based on three-dimensional experimental results.

[0003] Currently, in existing research on steam injection and steam drive, studies on steam channeling mechanisms have only proposed some possible hypotheses. Research reports on steam channeling mainly focus on the process technology level, with limited experimental research on the mechanism itself. While numerous studies describing steam channeling channels using methods such as potential detection, tracer methods, and physical simulation experiments have been conducted, a reliable set of results that combines experimental results with theoretical formula derivations and can be widely applied in oilfields has not yet been established. Most methods for identifying and describing steam channeling channels employ numerical simulation, but these methods focus on predicting macroscopic indicators and cannot delve into the underlying mechanisms and effects. Therefore, indoor experimental evaluation studies are needed to evaluate the development patterns of steam channeling channels during injection and displacement processes from the perspective of physical simulation experiments.

[0004] Currently, there are many methods for identifying dominant waterdrive channels, but the qualitative identification system is incomplete. Static-based identification techniques for dominant waterdrive channels are constrained by the precision and accuracy of geological parameters and are limited by dynamic monitoring data. Dynamic monitoring methods have technical blind spots, require combined testing, and are highly technical. Oilfield production data varies widely and sometimes fails to meet requirements. While dynamic-based identification techniques filter the correlation between dynamic data and channels, they have not established a binding method for dynamic-static correlation. Furthermore, a complete system for identifying and quantifying dominant channels from near-wellbore, inter-well, and overall block levels has not yet been established. Classification and grading descriptions are difficult, and quantitative characterization methods are lacking. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an experimental apparatus and method for the distribution morphology of dominant channels in steam-driven wells in heavy oil reservoirs. This method is simple, easy to implement, rapid, and effective. It allows for intuitive observation of the morphology of dominant channels in steam-driven wells and quantification of their size, analysis of their development characteristics, and the formation of a quantitative characterization method for dominant channels. Furthermore, it enables the identification of dominant channels based on field development conditions, classification of dominant channel types, and establishment of comprehensive evaluation criteria.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An experimental apparatus for the distribution pattern of dominant channels between steam-driven wells in heavy oil reservoirs includes:

[0008] An oil reservoir model includes an outer shell and a constant temperature chamber disposed inside the outer shell, the constant temperature chamber being filled with sand.

[0009] The injection system includes a steam generator, a crude oil storage tank, a formation water storage tank, two booster pumps, and two distilled water storage tanks. The input end of one of the booster pumps is connected to one of the distilled water storage tanks, and the output end is connected to the inlet of the steam generator. The outlet of the steam generator is connected to the inlet of the thermostatic chamber via a multi-way valve. The input end of the other booster pump is connected to the other distilled water storage tank, and the output ends are connected to the crude oil storage tank and the formation water storage tank, respectively. The outlets of the crude oil storage tank and the formation water storage tank are connected to the inlet of the thermostatic chamber via multi-way valves.

[0010] The measurement and control system includes a data acquisition unit and an operation terminal. The data acquisition unit is connected to the sensors on the reservoir model, and the data acquisition unit is electrically connected to the operation terminal.

[0011] The production system includes storage tanks for collecting fluids flowing out of the reservoir model.

[0012] Preferably, the experimental apparatus includes a square-shaped, detachable, temperature-controlled sand-filled box with an internal insulation layer that wraps around the sand particles.

[0013] Preferably, the experimental apparatus includes a number of vertical wells inside the constant temperature chamber, with high-permeability strips pre-placed between the vertical wells.

[0014] In the aforementioned experimental apparatus, preferably, the sand particle size and weight are determined by the following formula:

[0015]

[0016] Where τ is the tortuosity; K is the permeability; φ is the porosity; and S is the specific surface area.

[0017]

[0018] Where c is a constant of 1.2-1.4; Di is the particle size; and Gi is the content of particle size Di.

[0019] A second aspect of the present invention provides an experimental method for determining the distribution morphology of dominant channels between steam-driven wells in heavy oil reservoirs. The experimental method, based on the aforementioned experimental apparatus, includes the following steps:

[0020] The steam drive advantage channel is pre-equivalently set up, and the reservoir model is filled with particles according to the different porosity and permeability conditions required for the experiment. In the reservoir model, one injection well and multiple production wells are installed using the multi-point method, and temperature measurement points and pressure measurement points are arranged at appropriate distances.

[0021] The pore volume and porosity of the reservoir model were calculated according to the steam-driven oil recovery experiment operation procedure, and the initial condition temperature field and crude oil saturation field were established.

[0022] Start the injection system and the measurement and control system, set the flow rate, turn on the steam generator, set the temperature and adjust the steam dryness;

[0023] Based on the experimental design, the relevant parameters of the three-dimensional similarity criterion were designed to simulate the steam-driven oil recovery process. Steam was continuously injected into the injection well, and the produced fluid was collected and experimental records were made.

[0024] When the steam drive reaches an instantaneous oil-steam ratio below 0.1, the displacement ends, and a stable dominant channel is generated between the wells. Epoxy resin AB glue is injected, and after the epoxy resin AB glue solidifies, the reservoir model is opened, the dominant channel skeleton is taken out, the morphological characteristics and size are quantified, and the development pattern of the dominant channel is observed.

[0025] The experimental method described herein preferably includes the following parameters for the three-dimensional similarity criterion: oil layer thickness, production time, model permeability, injected steam dryness, steam drive outlet pressure, steam injection rate, and simulated oil viscosity.

[0026] The experimental method described herein preferably involves the following points during the selection and filling of the matrix sand particles: the matrix permeability is determined based on the actual reservoir properties, and heat-resistant resin adhesive is used to contact and bond the particles; large-diameter particles are selected to fill the dominant channels, and heat-resistant resin adhesive is used to contact and bond the particles; initially, to prevent the collapse of large particles, sodium thiosulfate is filled between the large particles in the dominant channels; the sand-filled core is heated to 100-120℃ for a certain period of time to solidify the particles and sublimate the sodium thiosulfate.

[0027] The present invention has the following advantages due to the adoption of the above technical solutions:

[0028] 1. The experimental method of this invention is based on a three-dimensional physical simulation experimental device. Targeting the dominant displacement channels generated between wells during steam flooding in heavy oil reservoirs, an experimental method is established based on similarity criteria. By simulating the expansion and distribution of dominant channels between injection and production wells, the morphological characteristics and development patterns of these channels are studied. The dominant channels are quantitatively and concretely characterized, and the crossflow characteristics and fluid distribution state between the injection well and surrounding connected wells during steam flooding are analyzed. This method utilizes a three-dimensional physical simulation model to simulate the original formation conditions, establish an initial temperature field and oil saturation field, and pre-set equivalent steam flooding dominant channels. A particle-filled model is selected according to different porosity and permeability conditions required for the experiment. After the steam flooding experiment, the dominant channels are solidified, and the colloidal skeleton is removed by opening the experimental device, thus obtaining the distribution morphology of the steam flooding dominant channels.

[0029] 2. This experimental method involves injecting epoxy resin AB glue after generating a stable vapor-driven dominant channel. After molding, the experimental device can be opened to remove the dominant channel skeleton, allowing for direct observation of its morphology and quantification of its size. This yields various physical property data of the dominant channel. The experimental results can be used to further classify vapor-driven dominant channels and establish a multi-parameter evaluation system. This provides important basic data for the prediction and evaluation of vapor-driven dominant channels in heavy oil blocks, thereby serving the formulation of vapor-driven dominant channel management and anti-channeling measures.

[0030] 3. This invention, by concretely representing the dominant channels of steam drive, analyzes the development morphology and expansion characteristics of these channels, which helps resolve intra-layer, inter-layer, and planar contradictions, guides the optimization of steam drive control measures, and improves the development effect of steam drive. Based on the similarity criteria for steam drive simulation and combined with the operating conditions of experimental equipment, this technology proportionally transforms actual mine operations and geometric conditions into physical model values, conducts three-dimensional physical simulation experiments, and studies a quantitative description method for dominant channels of steam drive. The experimental results can be converted into a mine prototype at the same scale.

[0031] 4. This experimental method is simple, easy to implement, rapid, and effective. It allows for direct observation of the morphology and quantification of the scale of dominant gas-driven channels, and analysis of their development characteristics. The experimental results can form a quantitative characterization method for dominant gas-driven channels, enabling the identification of these channels based on field development conditions, classification of channel types, and the establishment of comprehensive evaluation standards. This method is expected to produce experimental results and evaluation indicators with broad applicability, applicable to field operations in oilfields. It provides targeted solutions for the closure and remediation of dominant gas-driven channels, and has significant practical guiding significance for improving heavy oil recovery. Attached Figure Description

[0032] Figure 1 A diagram of a steam-driven three-dimensional physical simulation device provided in an embodiment of the present invention;

[0033] Figure 2This is a graph showing the relationship between permeability and mesh size provided in this embodiment of the invention;

[0034] Figure 3 This is a cross-sectional view of the reservoir model provided in this embodiment of the present invention;

[0035] Figure 4 This is a top view of the reservoir model and well placement method provided in this embodiment of the invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Definitions of abbreviations and key terms

[0038] (1) Heavy oil reservoir: A reservoir where the crude oil viscosity is greater than 50 mPa·s under reservoir conditions. Crude oil with a viscosity greater than 50 mPa·s under reservoir conditions or a viscosity greater than 100 mPa·s after degassing is called heavy oil. According to my country's heavy oil classification standard, crude oil with a viscosity of 100–10000 mPa·s and a relative density (20℃) greater than 0.92 is called ordinary heavy oil; crude oil with a viscosity of 10000–50000 mPa·s and a relative density greater than 0.95 is called extra-heavy oil; and crude oil with a viscosity greater than 50000 mPa·s and a relative density greater than 0.98 is called super-heavy oil (or natural bitumen).

[0039] (2) Steam Drive: This method involves injecting high-temperature steam into a selected number of wells under high pressure using a suitable well network. This creates a saturated steam zone around the injection wells, heating and displacing the crude oil into the production wells. It relies on the heat of the high-pressure steam to reduce the viscosity of the crude oil and decrease flow resistance. The hot water cooled and condensed by the steam is then propelled by the subsequently injected steam, driving the oil towards the production wells. The crude oil expands after being heated, which is beneficial for extraction. The evaporation of light components in the crude oil forms a miscible zone at the oil front, which helps improve the oil displacement efficiency.

[0040] (3) Dominant channels: During the long-term water / gas injection development of the oilfield, due to geological factors such as the heterogeneity of the oil layer and development factors such as unreasonable working system, the heterogeneous flow of injected water / gas is caused, which further aggravates the heterogeneity of the reservoir pore structure, resulting in the formation of high permeability zones and ultra-high permeability zones in the reservoir, i.e. dominant channels.

[0041] (4) Steam cavity: The hot water zone, vapor-liquid miscible zone and steam zone formed between the steam injection well and the production well. Crude oil and hot water in the oil layer flow towards the production well for extraction, and the hot water zone pulls the steam to expand towards the production well. In the early stage of steam injection development, the steam cavity is only formed near the steam injection well and is relatively small in size, and the steam expands well in the vertical direction.

[0042] (5) Experimental research: Experimental research is a controlled research method that assesses the effect of changes in one or more variables on one or more variables. The main purpose of an experiment is to establish causal relationships between variables. The general practice is for researchers to propose a tentative hypothesis about a causal relationship in advance and then test it through experimental operations.

[0043] Current research on dominant channels primarily focuses on water-driven channels generated during water injection development in sandstone reservoirs, with limited attention paid to dominant channels generated by steam-driven channels in heavy oil reservoirs. Known methods for studying steam-driven dominant channels mainly follow the approach used for water-driven channels, employing fuzzy clustering analysis based on field production data and development dynamics. Therefore, existing research lacks indoor three-dimensional physical simulation experimental methods and has not established universal standards, making it difficult to guarantee convenience, operability, and broad applicability in oilfields. The experimental method provided in this invention simulates actual production while establishing standardized classification and evaluation indicators, making it applicable to large-scale oilfield production and solving practical production problems.

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 1 As shown, the experimental apparatus for determining the distribution morphology of dominant channels between steam-driven wells in heavy oil reservoirs, as described in this invention, includes a reservoir model, an injection system, a measurement and control system, and a production system. The reservoir model includes an outer shell and a constant-temperature chamber housed within the shell, the chamber being filled with sand. The injection system includes a steam generator, a crude oil storage tank, a formation water storage tank, two booster pumps, and two distilled water storage tanks. The input end of one of the booster pumps is connected to one of the distilled water storage tanks, and its output end is connected to the inlet of the steam generator. The outlet of the steam generator is connected to multiple... A multi-way valve is connected to the inlet of the constant temperature chamber; the input end of another booster pump is connected to another distilled water storage tank, and the output end is connected to the crude oil storage tank and the formation water storage tank respectively. The outlets of the crude oil storage tank and the formation water storage tank are connected to the inlet of the constant temperature chamber through a multi-way valve; a measurement and control system includes a data acquisition unit and an operating terminal. The data acquisition unit is connected to the sensors on the reservoir model, and the data acquisition unit is electrically connected to the operating terminal; a production system includes a storage tank for collecting the fluid flowing out of the reservoir model.

[0046] Specifically, the booster pump is an ISCO pump: a high-pressure, high-precision plunger pump used to inject crude oil, formation water, and steam generated by the steam generator into the reservoir model at the required experimental speed; the steam generator: a mechanical device that uses fuel or other energy sources to heat distilled water into hot water or steam, used to simulate the steam-driven oil injection process; the crude oil / formation water container: the crude oil and formation water contained in the container are used to inject into the reservoir model, so that the model body simulates the original oil-bearing and water-bearing conditions of the oil layer; the high-pressure nitrogen cylinder: pressurizes the reservoir model by injecting gas to further compact the model, and at the same time can check the gas pipeline joints and model seals to prevent gas leakage; the six-way valve: changes the position of the sealing components in the valve body The relative positions of the valve body channels allow for connection or disconnection, thereby controlling the injection of different fluid devices within the injection system; the back pressure valve adjusts the pressure of the experimental device during fluid flow via a piston inside the valve, maintaining a balance between the internal pressure and the set pressure value; the data acquisition unit collects temperature and pressure data at various points on the physical model at different time points during the experiment, monitoring the temperature and pressure distribution; the measuring cylinder is used to collect crude oil, hot water, and other fluids produced in the steam displacement experiment for subsequent processing; the reservoir model body is a thermostatic, detachable sand-filling box, measuring 50cm×50cm×50cm, which can be directly filled with oil sand and uses a ceramic / PTFE jacket for easy MRI / CT scanning.

[0047] like Figure 3 As shown, the constant temperature box is a square-structured, removable sand-filled box with an internal insulation layer. The insulation layer wraps around the sand particles, and the sand particles form an oil layer after being filled with oil and water.

[0048] like Figure 2 As shown, the particle size and filling amount of the sand to be filled need to be determined. The specific process is as follows:

[0049] (1) Selection of sand particle size

[0050] Correction to Kozeny-Carman

[0051] Wherein, τ is the tortuosity, which is taken as 1.2 based on experimental results; after the formation of the gas-driven dominant channel, the permeability K, porosity φ and specific surface area S change.

[0052] The specific surface area of ​​the porous medium composed of particles used in the experiment needs to be determined.

[0053] c = 1.2 - 1.4, G i For particle size D i The content of is generally determined by mixing two types of sand in experiments.

[0054] Once the dominant channels are generated, and given the permeability value K and porosity value φ, the specific surface area of ​​the experimental sand-filled porous medium can be obtained:

[0055]

[0056] The required specific surface area S of the sand-filled pipe is calculated based on the required permeability K and porosity φ.

[0057] according to Figure 2 The relationship between permeability and particle size shown uses two particle sizes, D1 and D2. The content of selected particles, G1 and G2, is calculated using the specific surface area formula above, and these are used as the quartz sand filling the dominant channels.

[0058] (2) Physical simulation construction method

[0059] Figure 4 This is a schematic diagram of the matrix profile of a sand-filled rock core in a three-dimensional physical simulation experiment. Figure 4 This is a top view of the 3D model and the well layout. The 3D physical simulation experiment uses three vertical wells: Well A (steam injection well), Well B, and Well C (both production wells). The distance between the injection and production wells in the model is preset to 40cm. To generate a steam-driven dominant channel more quickly, a high-permeability strip is pre-placed between the injection and production wells, and the steam displacement experiment is conducted with Well A as the center.

[0060] When selecting and filling matrix sand particles, the following points should be noted: ① The matrix permeability should be determined based on the actual reservoir properties, and the particles should be bonded using heat-resistant resin dots. ② Large-diameter particles should be used to fill the dominant channels, and these particles should also be bonded using heat-resistant resin dots. ③ Initially, to prevent the collapse of large particles, sodium thiosulfate should be filled between the large particles in the dominant channels. ④ The sand-filled core should be heated to 100-120℃ for approximately 24 hours to solidify the particles and sublimate the sodium thiosulfate.

[0061] After the steam displacement experiment, the dominant channels were cured by injecting epoxy resin AB glue, facilitating direct observation and measurement. Epoxy resin AB glue is a two-component polymer material composed of epoxy resin and a curing agent, possessing advantages such as being non-toxic, environmentally friendly, highly transparent, highly hard, low in viscosity, and inexpensive. This experiment utilized epoxy resin AB glue to construct the dominant channel framework in the physical model, providing a reference for studying methods for steam-driven dominant channels.

[0062] A second aspect of this invention provides an experimental method for the distribution morphology of dominant channels between steam-driven wells in heavy oil reservoirs, comprising the following steps:

[0063] The steam drive advantage channel is pre-equivalently set up, and the reservoir model is filled with particles according to the different porosity and permeability conditions required for the experiment. In the reservoir model, one injection well and multiple production wells are installed using the multi-point method, and temperature measurement points and pressure measurement points are arranged at appropriate distances.

[0064] The pore volume and porosity of the reservoir model were calculated according to the steam-driven oil recovery experiment operation procedure, and the initial condition temperature field and crude oil saturation field were established.

[0065] Start the injection system and the measurement and control system, set the flow rate, turn on the steam generator, set the temperature and adjust the steam dryness;

[0066] Based on the experimental design, the relevant parameters of the three-dimensional similarity criterion were designed to simulate the steam-driven oil recovery process. Steam was continuously injected into the injection well, and the produced fluid was collected and experimental records were made.

[0067] When the steam drive reaches an instantaneous oil-steam ratio below 0.1, the displacement ends, and a stable dominant channel is generated between the wells. Epoxy resin AB glue is injected, and after the epoxy resin AB glue solidifies, the reservoir model is opened, the dominant channel skeleton is taken out, the morphological characteristics and size are quantified, and the development pattern of the dominant channel is observed.

[0068] The following establishes a similarity criterion for the dominant channel of steam drive, and uses it to calculate relevant experimental parameters:

[0069] In the process of establishing similarity criteria, the subscripts m and p represent the parameters in the model and the parameters of the actual oil layer, respectively.

[0070] With the similarity criterion group, the correspondence and equality of similarity criterion numbers can be used to transform prototype parameters into model parameters, and these parameters can then be used to design and build the model. For convenience, let r(X) be the scale of the parameters, i.e.

[0071]

[0072] 1. Establish similarity criteria:

[0073] ① Oil layer thickness: The relationship between the experimental model oil layer thickness and the actual formation thickness is as follows:

[0074]

[0075] In the formula, x p —Actual well spacing, m; x m —Experimental model well spacing, m; h p —Actual oil layer thickness, m; h m —Thickness of the oil layer in the experimental model, in meters.

[0076] The thickness of the simulated oil layer can be obtained by deformation as follows:

[0077]

[0078] ② Production time: Based on the three-dimensional experimental similarity criterion, the relationship between the model production time and the actual production time is as follows:

[0079]

[0080] After sorting, we can obtain:

[0081]

[0082] In the formula, t m —Model production time, min; t p —Actual production time, min; K —Permeability; φ —Porosity; K r —Relative permeability, which is the ratio of the effective permeability to the absolute permeability of the fluid phase; g —acceleration due to gravity, m / s² 2 ρ—density, kg / m³ 3 μ g —Gas viscosity, mPa·s; L —Length, m.

[0083] ③ Model permeability: Based on the three-dimensional experimental similarity criterion, the relationship between the experimental model and the actual permeability is obtained as follows:

[0084]

[0085] In the formula, ρo is the density of crude oil, kg / m³. 3 μo – crude oil viscosity, mPa·s; ΔS – change in oil saturation.

[0086] After sorting, we can obtain:

[0087]

[0088] In the formula, K m —Experimental model permeability; K p — Actual production penetration rate.

[0089] ④ Injected Steam Dryness: Based on the three-dimensional experimental similarity criterion, the relationship between the injected steam dryness of the experimental model and the actual steam dryness is obtained as follows:

[0090]

[0091] In the formula, x represents the steam dryness fraction; ΔT represents the difference between the steam injection temperature and the initial temperature; C w Specific heat capacity of saturated hot water, J / kg·℃; L v —Latent heat of vaporization of saturated steam, kJ / kg;

[0092] Based on the saturation temperature of the injected steam, determine the specific heat capacity C of the saturated hot water by referring to the relevant saturated steam properties. w and the latent heat of vaporization of saturated steam L v After sorting, we get:

[0093]

[0094] In the formula, x m —The model uses steam dryness; x p —Actual production steam dryness; T s —Steam temperature, °C; T i —Original stratum temperature, °C.

[0095] ⑤ Steam drive outlet pressure: Using the three-dimensional experimental similarity criterion, the relationship between the experimental model's production pressure difference and the actual production pressure difference is obtained as follows:

[0096]

[0097] In the formula, Δp is the displacement pressure difference (MPa); ρo is the density of crude oil (kg / m³). 3 .

[0098] If the injection pressure is the same as the saturated vapor pressure of the steam, then Δp = p s (T s )-p out After sorting, we get:

[0099]

[0100] p outm =p sm -r(ρ o )r(g)r(L)(p sp -p outp )

[0101] In the formula, p outm —Model outlet pressure, MPa; p outp —Actual production outlet pressure, MPa; p sm —Model steam injection pressure, MPa; p sp —Actual steam injection pressure, MPa.

[0102] ⑥ Steam injection rate: Using the three-dimensional experimental similarity criterion, the relationship between the steam injection rate of the experimental model and the actual production steam injection rate is obtained as follows:

[0103]

[0104] In the formula, i s —Injection rate, m 3 / d; S—Original oil saturation; t—Production time, d; φ—Porosity; ρ w —Density of water, kg / m³ 3 .

[0105] After sorting, we can obtain:

[0106]

[0107] In the formula, i sm —Model injection rate, m 3 / d;i sp —Actual injection rate, m 3 / d.

[0108] ⑦ Simulated oil viscosity: Based on the three-dimensional experimental similarity criterion, the relationship between the viscosity of the simulated oil used in the experiment and the viscosity of the actual formation crude oil is obtained as follows:

[0109]

[0110] In the formula, μ g —Vapor viscosity, mPa·s; ρ g —Steam density, kg / m³ 3 .

[0111] After sorting, we can obtain:

[0112]

[0113] In the formula, μ om —Model crude oil viscosity, mPa·s; μ op —Model crude oil viscosity, mPa·s.

[0114] The similarity criteria and design methods used in this experiment are referenced in Table 1.

[0115] Table 1. Similarity Criteria and Design Methods for Physical Simulation Experiments

[0116]

[0117]

[0118] In physical simulation experiments, appropriate similarity criteria can be selected for different research objectives. Studying the dominant channel of steam drive relies on steam injection; therefore, similarity criteria involving steam have a significant impact. Thus, selecting a highly sensitive similarity criterion can more realistically reflect the fluid's seepage and heat transfer patterns, making the experimental results more accurate and practical.

[0119] 2. Using the similarity criteria proposed above, conduct experiments to calculate the relevant parameters of the three-dimensional similarity criteria.

[0120] (1) Calculate the simulated oil layer thickness

[0121] The distance between the two wells on site is x p The oil layer thickness is h p ,but:

[0122]

[0123] Given that the well spacing between injection and production wells is 100m and the well spacing in the model is 40cm, the scale of the experimental model and the actual reservoir are:

[0124]

[0125] (2) Calculate the experimental production time

[0126] according to Derivation:

[0127]

[0128] Given that, from (1), the calculated results are r(L) = 0.004, r(Δρ) = 1, and r(K) = 0.004. r )=1, r(μ) g If r(φ) = 1, r(g) = 1, r(L) = 1, and r(K) = 1, then the time scale can be calculated:

[0129]

[0130] If the prototype time is 21600 min (15 days), the model time is 21600 × 0.004 = 86.4 min; that is, 15 days of steam injection in the field corresponds to 86.4 min in the laboratory; 1 day in the field corresponds to 5.76 min in the laboratory.

[0131] (3) Calculate steam dryness

[0132] Depend on Conclusion:

[0133]

[0134] The reservoir model used in the experiment employs formation water, and the steam injection temperature is kept consistent with that in the field. Therefore, the known condition r(C) is given. w )=1, r(ΔT)=1, r(L v =1, calculate the steam dryness ratio:

[0135]

[0136] The experiment can use the same injection steam dryness as the field.

[0137] (4) Calculate the viscosity of the model oil

[0138] according to The simulated oil viscosity of the calculation model is obtained as follows:

[0139]

[0140] Given that r(ρ) o)=1, r(μ) g )=1, r(ρ g If r(x) = 1 and r(x) = 1, then the viscosity ratio can be calculated:

[0141]

[0142] The crude oil used in the experiment was the same as the crude oil degassed on site.

[0143] (5) Calculate the model penetration rate

[0144] according to Conclusion:

[0145]

[0146] Given r(φ) = 1, r(ΔS) = 1, r(μ) o )=1, r(L)=0.004, r(ρ o Given r(g) = 1, r(t) = 1, and r(t) = 0.004, the permeability scale can be calculated.

[0147]

[0148] The calculated permeability is then corrected using the Reynolds number criterion.

[0149]

[0150] (6) Calculate the steam injection rate of the model

[0151] according to The steam injection rate can be calculated to obtain:

[0152]

[0153] Given that r(ρ) w Given r(φ) = 1, r(t) = r(L), r(ΔS) = 1, and r(L) = 0.004, the steam flow ratio can be calculated.

[0154]

[0155] If the prototype's daily steam injection rate is 225 t / d, the corresponding laboratory unit is 225 × 10⁻⁶. 6 / (24×60)=156250mL / min; the model value is 156250×0.004 2 = 2.5 mL / min; that is, the on-site steam injection rate of 225 t / d corresponds to 2.5 mL / min in the laboratory.

[0156] (7) Calculate the pressure difference in the model

[0157] according to The experimental operating pressure yields the following results:

[0158] r(Δp)=r(ρ o )r(g)r(L)

[0159] Given that r(ρ) o Given that r(g) = 1 and r(L) = 0.004, the pressure difference scale can be calculated.

[0160] r(Δp)=r(ρ o r(g)r(L)=r(L)=0.004

[0161] If the prototype value Δp = 5 MPa, then the model value is 5 × 0.004 = 0.02 MPa.

[0162] Based on the actual parameters of the single 56 heavy oil reservoirs and the parameters of the three-dimensional experimental device, the three-dimensional similarity criterion was used to obtain the three-dimensional physical simulation parameter table of steam drive for the single 56 heavy oil reservoirs, as shown in Table 2.

[0163] Table 2 Parameter Conversion Table between Reservoir Prototype and Scale Model

[0164]

[0165]

[0166] The present invention establishes similarity criteria for the dominant channel of steam drive and conducts three-dimensional physical simulation experiments. The main objectives are as follows: (1) To predict the actual steam drive dynamics in the oilfield through physical simulation experiments; (2) The geometric, physical properties and operating conditions of the actual oil layer are quite different from those of the experimental model. Based on the operating conditions of the experimental equipment, the oilfield conditions are converted into physical model values ​​according to a certain proportion according to similarity theory; (3) The experimental results of the physical model can be converted to the field prototype according to the same proportion, so as to obtain the corresponding results under the actual conditions of the oilfield.

[0167] This three-dimensional physical simulation experiment is based on similarity theory. The design of the model, the experimental operation process, the data processing, and the use of experimental results to illustrate the reservoir prototype are all guided by similarity theory.

[0168] After prolonged steam flushing, the reservoir pore structure changes. Injected steam flows along high-permeability, large-pore channels, continuously increasing the original pore throat radius and permeability, thus forming dominant steam drive channels. The emergence of these dominant channels exacerbates inter-layer conflicts and causes inefficient steam circulation, posing significant challenges to stable and increased production. The three-dimensional physical simulation experimental device provided by this invention can establish a physical simulation of the formation of dominant channels in heavy oil reservoirs under laboratory conditions.

[0169] The experimental method of this invention is based on the similarity criterion for steam-driven simulation. By selecting particle-filled models required for different porosity and permeability conditions, steam displacement experiments are conducted under laboratory conditions. The stable dominant channels are then solidified to visually study the distribution morphology of the steam-driven dominant channels. Based on the results of the three-dimensional physical simulation experiments, the steam-driven dominant channels can be identified and classified, and further detailed analysis and extended research can be carried out.

[0170] The implementation method of this technical solution can guide indoor researchers in conducting physical simulations of the evolution process of dominant channels in steam-driven oilfields and carrying out three-dimensional physical simulation experiments. Based on known actual field geometry and operating conditions, this method only requires mathematical calculations at a certain scale to convert the actual field conditions into physical model values, revealing the development law of dominant channels in steam-driven oilfields through experiments. The method uses simple equipment, is easy to operate, and can reasonably and effectively simulate the distribution and expansion of dominant channels between wells during steam-driven oilfields, ensuring the smooth progress of experimental research and enabling direct observation. This makes the experimental results reliable and provides guidance for the management and anti-channeling measures of dominant channels between wells in heavy oil reservoirs undergoing steam-driven oilfields.

[0171] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An experimental method for determining the distribution morphology of dominant channels between steam-driven wells in heavy oil reservoirs, the experimental method being based on an experimental apparatus for determining the distribution morphology of dominant channels between steam-driven wells in heavy oil reservoirs, the apparatus comprising: An oil reservoir model includes an outer shell and a constant temperature chamber disposed inside the outer shell, the constant temperature chamber being filled with sand. The injection system includes a steam generator, a crude oil storage tank, a formation water storage tank, two booster pumps, and two distilled water storage tanks. The input of one booster pump is connected to one of the distilled water storage tanks, and its output is connected to the inlet of the steam generator. The outlet of the steam generator is connected to the inlet of the constant temperature chamber via a multi-way valve. The input of the other booster pump is connected to the other distilled water storage tank, and its output is connected to both the crude oil storage tank and the formation water storage tank. The outlets of both the crude oil storage tank and the formation water storage tank are connected to the inlet of the constant temperature chamber via the multi-way valves. The measurement and control system includes a data acquisition unit and an operation terminal. The data acquisition unit is connected to the sensors on the reservoir model, and the data acquisition unit is electrically connected to the operation terminal. The production system includes storage tanks for collecting fluids flowing out of the reservoir model; The experimental method is characterized by the following steps: The steam drive advantage channel is pre-equivalently set up. Particles are selected to fill the reservoir model according to the different porosity and permeability conditions required for the experiment. An injection well and multiple production wells are installed in the reservoir model using a multi-point method, and temperature and pressure measuring points are arranged at appropriate distances. The pore volume and porosity of the reservoir model were calculated according to the steam-driven oil recovery experiment operation procedure, and the initial condition temperature field and crude oil saturation field were established. Start the injection system and the measurement and control system, set the flow rate, turn on the steam generator, set the temperature and adjust the steam dryness; Based on the experimental design, the relevant parameters of the three-dimensional similarity criterion were designed to simulate the steam-driven oil recovery process. Steam was continuously injected into the injection well, and the produced fluid was collected and experimental records were made. When the steam drive reaches an instantaneous oil-steam ratio of less than 0.1, the displacement ends and a stable dominant channel is generated between the wells. Epoxy resin AB glue is injected, and after the epoxy resin AB glue solidifies, the reservoir model is opened, the dominant channel skeleton is taken out, the morphological characteristics and size are quantified, and the development law of the dominant channel is observed. The matrix permeability is determined based on the actual reservoir properties. Heat-resistant resin adhesive is used to contact and bond the particles. Large-diameter particles are used to fill the dominant channels, and heat-resistant resin adhesive is used to contact and bond the particles. Initially, to prevent the collapse of large particles, sodium thiosulfate is filled between the large particles in the dominant channels. The sand-filled core is heated to 100-120℃ for a certain period of time to solidify the particles and sublimate the sodium thiosulfate.

2. The experimental method according to claim 1, characterized in that, The relevant parameters of the three-dimensional similarity criterion include oil layer thickness, production time, model permeability, injected steam dryness, steam drive outlet pressure, steam injection rate, and simulated oil viscosity.

3. The experimental method according to claim 2, characterized in that, The constant temperature chamber is a constant temperature detachable sand-filled chamber with an internal insulation layer that wraps the sand particles.

4. The experimental method according to claim 3, characterized in that, The constant temperature chamber contains several vertical wells, and high-permeability strips are pre-placed between the vertical wells.

5. The experimental method according to claim 4, characterized in that, The particle size and weight of the sand particles are determined by the following formula: in, τ For tortuosity; K For penetration rate; Porosity; S For comparison; in, c The constant is 1.2-1.4; D i Particle size; G i Particle size D i The content of.

Images