CN110162906B - Seepage equivalent seepage resistance method for tight oil reservoir and hydroelectric simulation system - Google Patents

Abstract

A constant-current power supply is converted from a stabilized voltage power supply by a voltage-current converter and is used for simulating constant-yield production, the yield is controlled at a lower value, fluid in a near wellbore zone is slowly extracted, sufficient time for the fluid in the far wellbore zone to flow to a wellbore is provided, the exploitation of a reservoir layer and the stability of the yield are facilitated, and therefore an experimental result is more accurate. The invention provides a seepage resistance formula considering heterogeneity, non-Darcy seepage and a cubic law, and can be better suitable for a new process for developing compact oil reservoirs such as a staged fracturing synchronous injection-production horizontal well and the like. Through the superposition principle and the parallel computation, the mutual influence among different wells is researched, the computation efficiency is improved, and the method has great guiding significance for field production. The flow rule of the shaft under different conditions can be obtained by simple experiment and calculation steps through the Thevenin theorem, the Nonton theorem, the function generator and the oscilloscope.

Description

An Equivalent Seepage Resistance Method and Hydroelectric Simulation System for Seepage in Tight Reservoirs

technical field

The invention relates to an equivalent seepage resistance method and a hydroelectric simulation system for tight oil reservoir seepage under constant production conditions, and belongs to the technical field of simulation methods for oil and gas field development research.

Background technique

At present, the research methods of reservoir seepage simulation are mainly divided into numerical simulation, core experiment and hydroelectric simulation. Complex structural wells such as multilateral wells, staged fracturing horizontal wells, fishbone wells, injection-production wells in the same well, and tertiary oil recovery technologies such as gas injection are the inevitable choices for the economical and effective development of tight oil reservoirs. The simulation method is more complex and difficult to implement. Core experiments can be carried out with actual reservoir cores, which are close to the actual geological conditions and injection-production technology, and can directly measure more accurate production data. , the cost is high, and it cannot meet the increasingly high requirements for seepage simulation of tight oil reservoirs. Therefore, the hydropower simulation experiment and the equivalent seepage resistance method have been paid more and more attention by people. According to the literature "Generalized Dual Flow in Mesopore Medium" and "Analytical Solutions for 1-D Waterflood Problems Including Capillary Effects", the circuit law and the reservoir seepage law can be paired with each other according to the principle of hydroelectric similarity, and the hydroelectric simulation experiment and the equivalent seepage flow can be developed. The resistance method uses a conductive medium to simulate the formation, and applies an electric field generated by a certain potential difference on the medium to simulate the stable seepage field in the formation. It is a simple and effective method to study the steady-state productivity of tight oil reservoirs. Voltage data can be converted into production data by using a similar proportional relationship, and can be applied to various complex wellbore and fracture models.

Because the constant current power supply is easy to burn out when the circuit is cut off, which is not safe enough, the traditional hydropower simulation experiment and the equivalent seepage resistance method only use the constant current power supply. Therefore, it is only suitable for constant pressure production. The law of interchangeability of voltage-stabilized and constant-current power supply models, Thevenin's theorem, and Norton's theorem are not applied, so solving the model requires solving a large number of equations, which is difficult to apply to complex well patterns.

Therefore, the present invention adopts the law of constant voltage and constant current power supply model interchange to transform the seepage equivalent circuit diagram, which can continuously simplify the well pattern, and the Thevenin's theorem and Norton's theorem can obtain this Well production at different pressures or pressure at different production rates. Using the superposition principle, the mutual influence between the wells can be obtained.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention discloses an equivalent seepage resistance method for seepage in tight oil reservoirs under the condition of constant production.

The invention also discloses a hydropower simulation system for realizing the above method.

Summary of the invention:

The present invention is the first time that the constant current power supply is introduced into the hydropower simulation experiment. On the basis of the traditional hydropower simulation device, the voltage and current converter is used to convert the constant current power supply into a constant current power supply, which is used to simulate the production of constant output, and the output is controlled at a relatively high level. If the value is low, the fluid in the near-wellbore zone is produced slowly, giving enough time for the fluid in the far-wellbore zone to flow to the wellbore, which is more conducive to the stability of the reservoir production and production, so the experimental results are more accurate.

The present invention provides a new electrical simulation system and an equivalent seepage resistance method for revealing the seepage law of a horizontal well, so as to solve the following problems in the prior art: First, the existing electrical simulation device and the equivalent seepage resistance method are mainly suitable for In the case of constant pressure production, but for tight oil reservoirs, during constant pressure production, the fluid near the wellbore flows to the wellbore, and it is difficult to produce in the far-well zone, the production declines rapidly, and the results are not accurate. Second, the existing electrical simulation experimental device and equivalent seepage resistance method have not yet adopted Thevenin's theorem, Norton's theorem and oscilloscope. To study the influence of wellhead pressure radius and fracture width on production requires repeated experiments and calculations, and the steps are complicated. Third, the existing equivalent seepage resistance method does not simplify the dual circuit with the reservoir and needs to solve a large number of equations. Fourth, the existing equivalent seepage resistance method does not use the superposition theorem and cannot study the effect of each well on the seepage field. Fifth, the existing equivalent seepage resistance method does not consider reservoir heterogeneity and non-Darcy seepage, so it cannot be applied to tight oil reservoirs. Sixth, provide a simple experiment and calculation method that can study the seepage law of horizontal wells with simultaneous injection and production of staged fracturing.

The detailed technical scheme of the present invention is as follows:

An equivalent seepage resistance method for seepage in tight oil reservoirs under the condition of constant production, comprising the following simulation experiments using the principle of hydroelectric simulation, and is characterized in that:

In a hydropower analog circuit, a constant pressure power supply and a resistor in series are equivalent to a constant current power supply and a resistor in parallel. Dual to the reservoir, a constant pressure well or boundary is equivalent to two wells: one internal resistance is equal to this well and the wellhead pressure is 0 injection well and a well with constant flow rate production without internal resistance, the flow rate is equal to the wellhead pressure divided by the internal resistance of the well;

The short-circuit dual is that the wellhead pressure is 0;

Open dual is the output is 0;

The specific process of this method is:

1) Draw the equivalent circuit diagram of reservoir seepage, and find out the internal resistance and external resistance of the equivalent current source; mark the required parameter as point C;

2) Determine whether the equivalent circuit diagram is the simplest circuit diagram: if so, directly obtain the parameters corresponding to point C; if not, fix point C and convert the regulated power supply into a regulated current power supply;

3) Use the series and parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram.

Preferably according to the present invention, when the seepage resistance method of equivalent seepage resistance of tight oil reservoirs under the condition of constant production is applied to a well pattern:

Well group or Well A acting alone means that except Well A, other constant production wells are opened, and other constant pressure wells are short-circuited;

Dual the superposition law into the reservoir, where the reservoir pressure field includes multiple pressure fields generated by the individual actions of different wells;

The specific process of this method is:

1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source;

2) Judge whether the effects of all wells on point C have been studied: if so, the sum of the effects of all wells on point C is the parameter of point C; if not, take one or a group of wells A;

3) The remaining constant flow wells are open circuit, and the constant pressure wells are short circuited;

4) Use the series-parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram, and repeat step 2).

Preferably according to the present invention, by considering heterogeneity, non-Darcy seepage, and cubic law, it is used to simulate staged fracturing synchronous injection-production wells:

When there is a fractal structure in the reformed area of the reservoir, the permeability is distributed in a linear, exponential, and power-law pattern, which is expressed as

k(x, y)=k ₀ f _x (x)f _y (y) (1)

Among them, k is the reservoir permeability, m ² ; k ₀ is the near-well and near-hydraulic fracture permeability, m ² ; x is the direction along the hydraulic fracture, m; y is the direction along the horizontal well, m; D is the fractal dimension f _x (x) and f _y (y) represent the law of permeability decreasing along the x and y directions, respectively.

When the permeability decreases in a linear pattern along the x and y directions

k(x, y)=k ₀ (1-Dx)(1-Dy) (2)

When the permeability decreases exponentially along the x and y directions

k(x, y)=k ₀ e ^-Dx e ^-Dy (3)

When the permeability decreases along the x and y directions in a power-law pattern

k(x, y)=k ₀ x ^-D y ^-D (4)

The external resistance of the reservoir reformation zone is expressed as

Among them, 1 is the hydraulic fracture length, m; μ is the viscosity of crude oil, Pa·s; R is the seepage resistance of formation fluid; h is the height of the reservoir, m.

Substitute formula (2)(3)(4) into formula (5) to get

When there is a low-speed non-Darcy seepage in the crude oil in the unreformed area, and the flow rate and the pressure gradient are in a power-law relationship, the external resistance of the unreformed area is given by the Ikuko-Ramey method.

Among them, G is the non-Darcy flow coefficient of the unmodified area, and m is the non-Darcy flow index. When m=1, the flow in the unmodified region is Darcy flow, G is the permeability of the unmodified region, and _u is the length of the unmodified region, m.

Preferably according to the present invention, the seepage resistance method of equivalent seepage resistance of tight oil reservoirs under the condition of constant production also includes:

The Thevenin's theorem and Norton's theorem are dualized to the oil reservoir, in which, if any one or a group of wells A is taken out of a well pattern, the rest of the well pattern is equivalent to well A as:

A constant pressure production well B, the pressure of the constant pressure production well B is equal to the pressure when the well A is open and the internal resistance is infinite, and the internal resistance of the constant pressure production well B is equal to the flow resistance of the rest when the well A acts alone;

Or it is equivalent to the production well C and the injection well D, which is equivalent to the internal resistance of the production well C equal to the flow resistance of the rest when the well A acts alone, the wellhead pressure is 0, the injection well D has no internal resistance, and the injection volume is equal to the well A. The output when A is short-circuited and the internal resistance is 0;

The specific process of this method is:

1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source;

2) Assuming that the remaining constant pressure wells other than Well A are short-circuited and the constant-flow wells are open, find the resistance Rb generated by the rest of the well pattern, including the following two:

2-1) The pressure pb when well A is short-circuited and the internal resistance is 0, then the rest is equivalent to well B, the pressure of well B is equal to pb, and the internal resistance is equal to Rb;

2-2) The flow rate Qb when well A is open and the internal resistance is infinite, then the rest is equivalent to production well C and injection well D, the internal resistance of well C is equal to Rb, the wellhead pressure is 0, well D has no internal resistance, and the injection The amount is equal to Qb;

3) Convert the equivalent circuit diagram into the simplest circuit diagram;

4) Obtain production data under different working systems and wellhead dimensions.

A hydropower simulation system, comprising:

Electrolyzer: used to hold electrolyte solution, salt water, ionic liquid and mineral oil can be selected according to actual needs;

Voltage-to-current converter: converts the regulated power supply into a regulated current power supply to simulate constant-volume production, and its output current is adjustable;

Voltmeter: connected between the simulated well or probe and position sensor and the simulated fracture to obtain simulated bottom hole pressure, and connected with the data collector;

Ammeter: connected between the voltage-current converter and the said simulated well to obtain production, and connected with the data collector;

Data collector: used to transmit the voltage value and current value automatically recorded in the hydropower simulation system to the computer.

According to the preferred embodiment of the present invention, when the hydroelectric simulation system is used to simulate the synchronous injection-production well of segmented fracturing, an oscilloscope is used instead of a voltmeter and an ammeter to realize the data acquisition of the voltage and current values; a function generator is used as the A regulated power supply, which generates a sawtooth wave, and obtains the output value under different simulated pressures or the pressure value under different simulated output.

Preferably according to the present invention, in the hydropower simulation system, the simulated well is a copper model of a horizontal well of a staged fracturing synchronous injection-production well.

Preferably according to the present invention, the hydroelectric simulation system further comprises: a probe and a position sensor;

The probe and the position sensor are used for: using the probe to carry out simulated three-dimensional free movement and simulated measurement in the electrolytic cell.

The technical advantages of the present invention are:

First, the present invention introduces the steady-flow power supply into the hydropower simulation system and the equivalent seepage resistance method for the first time, that is, production with constant production can be considered. Through production with constant production, the decline in production can be alleviated, and the fluid in the far-well zone can be used to adapt to tight oil reservoirs. It can also simplify the solution steps of the seepage equations, making the results more accurate.

Second, the present invention converts the voltage-current converter into a constant-current power supply, which prevents the constant-current power supply from being burned out due to an open circuit, and greatly protects the safety of the experimenter's life.

Third, the present invention provides a seepage resistance formula considering heterogeneity, non-Darcy seepage and cubic law, which can be better applied to new techniques for development of tight oil reservoirs such as staged fracturing simultaneous injection and production horizontal wells.

Fourth, through the superposition principle and parallel calculation, the mutual influence between different wells is studied, which improves the calculation efficiency and has great guiding significance for field production.

Fifth, through Thevenin's theorem, Norton's theorem and an oscilloscope, the flow law of the wellbore under different conditions can be obtained with relatively simple experimental and calculation steps.

Description of drawings

1 is a schematic structural diagram of a hydroelectric simulation system for the seepage law of a horizontal well with staged fracturing and simultaneous injection and production provided by the present invention;

2 is a schematic structural diagram of a hydropower simulation system for studying the influence of crack size and working system on production parameters provided by the present invention;

In Figures 1 and 2, the hydropower simulation system includes: 1. regulated power supply; 2. voltage-current converter; 3. ammeter; 4. voltmeter; 5. electrolytic cell; 6. copper sheet for simulating boundary; 7. Copper sheet for simulating injection cracks; 8. Copper sheet for simulating production cracks; 9. Probe and position sensor; 10. Data collector; 11. Computer; 12. Function generator; 13. Oscilloscope;

Fig. 3 is the flow chart of the equal seepage resistance method according to the present invention;

Fig. 4 is the flow chart that the present invention adopts the superposition principle to calculate the influence between different wells;

Fig. 5 is the flow chart of the present invention adopting Thevenin's theorem and Norton's theorem to calculate the influence of crack size and working system on production parameters;

Fig. 6 is the reservoir parameter table of application examples 1 and 2;

Figure 7 shows the flow rates of five fractures in Application Example 1, listed in order from left to right;

Figure 8 shows the flow and pressure of the five fractures in Application Example 2, listed in order from left to right;

Fig. 9 is the reservoir parameter of application example 3;

Figure 10 shows the five fracture pressures in Application Example 3, listed in order from left to right.

Detailed ways

The embodiments of the present invention are described in detail with reference to the accompanying drawings, but are not limited thereto.

A hydroelectric simulation system, comprising: an electrolytic cell 5: used for holding an electrolyte solution, and salt water, ionic liquid, and mineral oil can be selected according to actual needs;

Voltage-to-current converter 2: converts the regulated power supply into a regulated current power supply, which is used to simulate constant-volume production, and its output current is adjustable;

Voltmeter 4: connected between the two output terminals of the voltage-current converter to obtain the simulated bottom hole pressure, and connected with the data collector;

Ammeter 3: connected between the voltage-to-current converter and the simulated well to obtain production, and connected to the data collector;

Data collector 10 : used to transmit the voltage value and current value automatically recorded in the hydropower simulation system to the computer 11 .

When the hydroelectric simulation system is used to simulate the synchronous injection-production well of segmented fracturing, the oscilloscope 13 is used instead of the voltmeter 4 and the ammeter 3 to realize the data acquisition of the voltage value and the current value; the function generator 12 is used as a voltage regulator. The power supply, the regulated power supply generates a sawtooth wave, and obtains the output value under different simulated pressures or the pressure value under different simulated output.

In the hydropower simulation system, the simulated well is a copper model of a horizontal well of a staged fracturing simultaneous injection-production well, such as the copper sheet 8 used to simulate production fractures in Figures 1 and 2 .

The hydroelectric simulation system further includes: a probe and a position sensor 9;

The probe and the position sensor 9 are used for: using the probe to perform free movement and simulated measurement in the electrolytic cell 5 in a simulated three-dimensional direction.

The work flow of the hydropower simulation system of the present invention includes: placing the electrolytic cell 5 on a workbench, and placing the copper sheets used to simulate boundaries and cracks in the electrolytic cell 5 . The voltage-to-current converter converts the regulated power supply into a regulated current power supply, and is connected to the copper sheet used to simulate production and injection into cracks to simulate constant flow injection and mining. The copper strip used to simulate the boundary is connected to the regulated power supply 1, which can be used to simulate the constant voltage boundary. The voltmeter 4 is connected between the copper pieces of the simulated crack and boundary, or between the copper piece of the simulated boundary and the probe, and the ammeter 3 is connected between the copper piece of the simulated crack and the voltage-current converter 2 to adjust the voltage and current The converter 2 outputs current, and the data collector 10 can collect probe position, current, and voltage in real time, and then draw the pressure field through the computer 11 .

Embodiment 1,

An equivalent seepage resistance method for seepage in tight oil reservoirs under the condition of constant production, including the following simulation experiments using the principle of hydropower simulation. In a reservoir, a constant pressure well or boundary is equivalent to two wells: an injection well with internal resistance equal to this well and 0 wellhead pressure and a constant flow producing well with no internal resistance, with flow rate equal to wellhead pressure divided by the wellhead pressure The internal resistance of ; the short-circuit dual is the wellhead pressure of 0; the open-circuit dual is the output of 0;

The specific process of this method is:

1) Draw the equivalent circuit diagram of reservoir seepage, and find out the internal resistance and external resistance of the equivalent current source; mark the required parameter as point C;

2) Determine whether the equivalent circuit diagram is the simplest circuit diagram: if so, directly obtain the parameters corresponding to point C; if not, fix point C and convert the regulated power supply into a regulated current power supply;

3) Use the series and parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram.

Embodiment 2,

The equivalent seepage resistance method of tight oil reservoir seepage flow under a constant production condition as described in Example 1, when applied to a well pattern:

Well group or Well A acting alone means that except Well A, other constant production wells are opened, and other constant pressure wells are short-circuited;

Dual the superposition law into the reservoir, where the reservoir pressure field includes multiple pressure fields generated by the individual actions of different wells;

The specific process of this method is:

1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source;

2) Judge whether the effects of all wells on point C have been studied: if so, the sum of the effects of all wells on point C is the parameter of point C; if not, take one or a group of wells A;

3) The remaining constant flow wells are open circuit, and the constant pressure wells are short circuited;

4) Use the series-parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram, and repeat step 2).

Embodiment 3,

As described in Example 1, an equivalent seepage resistance method for tight oil reservoir seepage under constant production conditions, the Thevenin's theorem and Norton's theorem are dualized into the oil reservoir, wherein any well or a group of wells are taken out from a well pattern A, the rest of the well pattern is equivalent to well A as:

A constant pressure production well B, the pressure of the constant pressure production well B is equal to the pressure when the well A is open and the internal resistance is infinite, and the internal resistance of the constant pressure production well B is equal to the flow resistance of the rest when the well A acts alone;

Or it is equivalent to the production well C and the injection well D, which is equivalent to the internal resistance of the production well C equal to the flow resistance of the rest when the well A acts alone, the wellhead pressure is 0, the injection well D has no internal resistance, and the injection volume is equal to the well A. The output when A is short-circuited and the internal resistance is 0;

The specific process of this method is:

1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source;

2) Assuming that the remaining constant pressure wells other than Well A are short-circuited and the constant-flow wells are open, find the resistance Rb generated by the rest of the well pattern, including the following two:

2-1) The pressure pb when well A is short-circuited and the internal resistance is 0, then the rest is equivalent to well B, the pressure of well B is equal to pb, and the internal resistance is equal to Rb;

2-2) The flow rate Qb when well A is open and the internal resistance is infinite, then the rest is equivalent to production well C and injection well D, the internal resistance of well C is equal to Rb, the wellhead pressure is 0, well D has no internal resistance, and the injection The amount is equal to Qb;

3) Convert the equivalent circuit diagram into the simplest circuit diagram;

4) Obtain production data under different working systems and wellhead dimensions.

As shown in Figure 2, in order to study the production under different pressures of a certain fracture or the pressure under different production during constant flow production, a function generator is used to generate a sawtooth wave, and the sawtooth wave is input to the X channel of the oscilloscope and the voltage-current converter, and the The current that changes with time period is input to the copper sheet that simulates the crack to be studied, and the voltage between the copper sheet or the probe and the copper sheet of the simulated boundary is input to the Y channel of the oscilloscope, and the difference between the crack production and the pressure field can be obtained. relation.

The working process of the equivalent seepage resistance method of the present invention: draw the equivalent circuit diagram of the reservoir seepage, find out the internal resistance and external resistance, mark the point where the required parameters are located, and set it as point C.

When there is a fractal structure in the reformed area of the reservoir, the permeability is distributed in a linear, exponential, and power-law pattern, which is expressed as

k(x, y)=k ₀ f _x (x)f _y (y) (1)

Among them, k is the reservoir permeability, m ² ; k ₀ is the near-well and near-hydraulic fracture permeability, m ² ; x is the direction along the hydraulic fracture, m; y is the direction along the horizontal well, m; D is the fractal dimension f _x (x) and f _y (y) represent the law of permeability decreasing along the x and y directions, respectively.

When the permeability decreases in a linear pattern along the x and y directions

k(x, y)=k ₀ (1-Dx)(1-Dy) (2)

When the permeability decreases exponentially along the x and y directions

k(x, y)=k ₀ e ^-Dx e ^-Dy (3)

When the permeability decreases along the x and y directions in a power-law pattern

k(x, y)=k ₀ x ^-D y ^-D (4)

The external resistance of the reservoir reformation zone is expressed as

Among them, 1 is the hydraulic fracture length, m; μ is the viscosity of crude oil, Pa·s; R is the seepage resistance of formation fluid; h is the height of the reservoir, m.

Substitute formula (2)(3)(4) into formula (5) to get

When there is a low-speed non-Darcy seepage in the crude oil in the unreformed area, and the flow rate and the pressure gradient are in a power-law relationship, the external resistance of the unreformed area is given by the Ikuko-Ramey method.

Among them, G is the non-Darcy flow coefficient of the unmodified area, and m is the non-Darcy flow index. When m=1, the flow in the unmodified region is Darcy flow, G is the permeability of the unmodified region, and _u is the length of the unmodified region, m.

The flow in the hydraulic fracture follows the cubic law, and the internal resistance of the hydraulic fracture is

Among them, w is the hydraulic fracture width, m;

As shown in Figure 3, at fixed point C, the equivalent circuit diagram is simplified by using the law of exchange of regulated power supply and regulated current power supply and the law of series and parallel. A well or boundary with pressure p and internal resistance R can be equivalent to two wells: a well with internal resistance R and pressure 0 and a well with flow rate Q, and vice versa. The relationship between p, Q, R is as follows

The equivalent seepage resistance method shown in Figure 4 can be calculated in parallel, each calculation node corresponds to a well A, and the constant flow wells except A are open-circuited and the constant-pressure wells are short-circuited. The method shown in Figure 3 can be used to obtain The influence of well A on the flow of all wells is filled in a matrix, and then each node takes out the influence of all wells on well A from the matrix, and superimposes the production data of well A.

As shown in Figure 5, the well group or well A is taken from the well pattern, and the rest of the well pattern can be equivalent to a well B with pressure p _b and internal resistance R _b for well A, assuming that well A is open circuit And the internal resistance is infinite, the pressure of well A can be obtained by the method shown in Figure 3 and Figure 4, which is p _b . Assuming that the rest of the constant-flow wells are open and the constant-pressure wells are short-circuited, the flow resistance generated by the rest is R _b ; It can be equivalent to production well C and injection well D. The internal resistance of well C is R _b , the wellhead pressure is 0, the internal resistance of well D is 0, and the flow rate is Q _b . Assuming that well A is short-circuited and the internal resistance is 0, Figure 3 can be used. The method shown in Fig. 4 finds the flow rate of well A, which is Q _b . By changing the conditions of well A, the flow law of well A under different conditions can be obtained.

Application example 1,

Based on the paper "Temporal scale analysis of two phase flow in fracturedwell", patents "US 2015/0007996" and "US 2014/015603", the horizontal well model of staged fracturing with simultaneous injection and production as shown in Figure 1 is studied, that is, the same horizontal well There are injection cracks and production cracks at the same time, and the parameters are shown in Figure 6. The seepage resistance method and the experimental device in Chinese patent CN201610822268.2 were used to obtain the hydraulic fracture production and injection volume, respectively. Using the superposition principle and the voltage-stabilized power supply and constant-current power supply interchange theorem, the obtained flow rates of the five fractures were from left to right. As shown in Figure 7. Taking the experimental results as reference solutions, the correctness of this method is verified. The error is mainly due to the boundary effect of hydraulic fractures.

Application example 2,

The research data is shown in the horizontal well model of staged fracturing simultaneous injection and production in Figure 6. The production and injection fractures are produced at a constant flow rate, and the production and injection volume of the five fractures are shown in Figure 8 from left to right. The equivalent seepage resistance method and the hydroelectric simulation system of the present invention are used to obtain the pressure of each fracture, and the boundary on one side, the boundary on the other side and all fractures are equivalent to a constant pressure well, and it is obtained when the total injection volume of the well pattern is equal to the total production , the fracture pressure closest to the boundary is equal to the boundary pressure. Using the said constant current power supply interchange theorem, the obtained five crack pressures from left to right are shown in Figure 8, which further verifies the correctness of this method. The errors are mainly due to round-off errors in the calculations.

Application example 3,

The horizontal well model with staged fracturing and simultaneous injection and production is studied as shown in Fig. 1. The area between the fractures includes the reformed area and the non-reformed area. The permeability k of the reformed area not only decreases to 10% along the x-axis, but also decreases along the y-axis. When the axis decreases to 10%, there is low-velocity non-Darcy seepage in the unreformed area. When there is non-Darcy flow and heterogeneity in the reservoir, the pressure of the production well decreases.

The principle and implementation of the present invention are described above, and use cases are provided. For those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (7)

1. a tight oil reservoir seepage-equivalent seepage resistance method under a constant output condition, comprises utilizing the hydroelectric simulation principle to carry out the following simulation experiments, it is characterized in that: In the hydropower analog circuit, the series connection of a constant pressure power supply and a resistor is equivalent to a constant current power supply and a parallel connection of the resistor. Dual to the oil reservoir, a constant pressure well or boundary is equivalent to two wells: an injection well with a wellhead pressure of 0 is called Well A, a well that produces at a constant flow rate without internal resistance, is called Well B. The two wells can be equivalent to a constant pressure well C. The pressure of Well C is equal to the production of Well B multiplied by the internal resistance of Well A; Well C or The constant pressure boundary is equivalent to two wells A and B: the internal resistance of the injection well A is equal to the internal resistance of the well C; the wellhead pressure of the well C is 0; the production of the well B is constant production without internal resistance, and the output is equal to the wellhead pressure divided by the internal resistance of the well resistance; The short-circuit dual is that the wellhead pressure is 0; Open dual is the output is 0; The specific process of this method is: 1) Draw the equivalent circuit diagram of reservoir seepage, and find out the internal resistance and external resistance of the equivalent current source; mark the required parameter as point C; the required parameter is the well C whose production or pressure is to be obtained ; 2) Determine whether the equivalent circuit diagram is the simplest circuit diagram: if so, directly obtain the parameters corresponding to point C; if not, fix point C and convert the regulated power supply into a regulated current power supply; 3) Use the series and parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram. 2. the seepage-equivalent seepage resistance method for tight oil reservoir seepage under a constant production condition according to claim 1, is characterized in that, by considering heterogeneity, non-Darcy seepage, cubic law, for simulating subsection Fracturing simultaneous injection and production wells: When there is a fractal structure in the reformed area of the reservoir, the permeability is distributed in a linear, exponential, and power-law pattern, which is expressed as k(x, y)=k ₀ f _x (x)f _y (y) (1) Among them, k is the reservoir permeability, m ² ; k ₀ is the near-well and near-hydraulic fracture permeability, m ² ; x is the direction along the hydraulic fracture, m; y is the direction along the horizontal well, m; D is the fractal dimension number; f _x (x) and f _y (y) represent the decreasing law of permeability along the x and y directions, respectively; When the permeability decreases in a linear pattern along the x and y directions k(x, y)=k ₀ (1-Dx)(1-Dy) (2) When the permeability decreases exponentially along the x and y directions k(x, y)=k ₀ e ^-Dx e ^-Dy (3) When the permeability decreases along the x and y directions in a power-law pattern k(x, y)=k ₀ x ^-D y ^-D (4) The external resistance of the reservoir reformation zone is expressed as

Among them, 1 is the hydraulic fracture length, m; μ is the viscosity of crude oil, Pa s; R is the seepage resistance of formation fluid; h is the height of the reservoir, m; Substitute formula (2)(3)(4) into formula (5) to get

Among them, l is the hydraulic fracture length, m; μ is the viscosity of crude oil, Pa s; R is the seepage resistance of formation fluid; h is the height of the reservoir, m; When there is a low-speed non-Darcy seepage in the crude oil in the unreformed area, and the flow rate and the pressure gradient are in a power-law relationship, the external resistance of the unreformed area is given by the Ikuko-Ramey method.

Among them, G is the non-Darcy flow coefficient in the unmodified area, m is the non-Darcy flow index; when m=1, the flow in the unmodified region is Darcy flow, G is the permeability of the unmodified region, and _u is the unmodified region. The length of the transformation area, m; The flow in the hydraulic fracture follows the cubic law, and the internal resistance of the hydraulic fracture is

where w is the hydraulic fracture width, m. 3. the seepage-equivalent seepage resistance method of tight oil reservoir seepage under a kind of constant production condition according to claim 1, it is characterized in that, the seepage-equivalent seepage resistance method of tight oil reservoir seepage under described constant production condition is applied in a When the well pattern is in: Well group acting alone or Well A acting alone means that except Well A, other constant production wells are opened and other constant pressure wells are short-circuited; Dual the superposition law into the reservoir, where the reservoir pressure field includes multiple pressure fields generated by the individual actions of different wells; The specific process of this method is: 1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source; 2) Judge whether the effects of all wells on point C have been studied: if so, the sum of the effects of all wells on point C is the parameter of point C; if not, take one or a group of wells A; 3) The remaining constant flow wells are open circuit, and the constant pressure wells are short circuited; 4) Use the series-parallel connection of resistors and power supplies to simplify the circuit diagram to the simplest circuit diagram, and repeat step 2). 4. the tight oil reservoir seepage equivalent seepage resistance method under a kind of constant production condition according to claim 1, is characterized in that, the tight oil reservoir seepage equivalent seepage resistance method under the described constant production condition also comprises: The Thevenin's theorem and Norton's theorem are dualized to the oil reservoir, in which, if any one or a group of wells A is taken out of a well pattern, the rest of the well pattern is equivalent to well A as: A constant pressure production well B, the pressure of the constant pressure production well B is equal to the pressure when the well A is open and the internal resistance is infinite, and the internal resistance of the constant pressure production well B is equal to the flow resistance of the rest when the well A acts alone; Or it is equivalent to the production well C and the injection well D. The equivalent internal resistance of the production well C is equal to the flow resistance generated by the rest when the well A acts alone. The wellhead pressure is 0, the injection well D has no internal resistance, and the injection volume is equal to the well A. The output when A is short-circuited and the internal resistance is 0; The specific process of this method is: 1) Draw the equivalent circuit diagram of the reservoir seepage, and obtain the internal resistance and external resistance of the equivalent current source; 2) Assuming that the remaining constant pressure wells other than Well A are short-circuited and the constant-flow wells are open, find the resistance Rb generated by the rest of the well pattern, including the following two: 2-1) The pressure pb when well A is short-circuited and the internal resistance is 0, then the rest is equivalent to well B, the pressure of well B is equal to pb, and the internal resistance is equal to Rb; 2-2) The flow rate Qb when well A is open and the internal resistance is infinite, then the rest is equivalent to production well C and injection well D, the internal resistance of well C is equal to Rb, the wellhead pressure is 0, well D has no internal resistance, and the injection The amount is equal to Qb; 3) Convert the equivalent circuit diagram into the simplest circuit diagram; 4) Obtain production data under different working systems and wellhead dimensions. 5. The hydroelectric simulation system of the seepage-equivalent seepage resistance method in tight oil reservoirs as claimed in claim 1, characterized in that, comprising: Electrolyzer: used to hold electrolyte solution, Voltage-to-current converter: converts the regulated power supply into a regulated current power supply to simulate constant-volume production, and its output current is adjustable; Voltmeter: connected between the simulated well or probe and position sensor and the simulated fracture to obtain simulated bottom hole pressure, and connected with the data collector; Ammeter: connected between the voltage-current converter and the said simulated well to obtain production, and connected with the data collector; Data collector: used to transmit the voltage value and current value automatically recorded in the hydropower simulation system to the computer. 6. The hydroelectric simulation system of the seepage-equivalent seepage resistance method in tight oil reservoirs as claimed in claim 5, wherein the hydroelectric simulation system utilizes an oscilloscope instead of a voltage when used for simulating a staged fracturing synchronous injection-production well The meter and the ammeter realize the data collection of the voltage value and the current value; the function generator is used as a regulated power supply, and the regulated power supply generates a sawtooth wave to obtain the output value under different simulated pressures or the pressure value under different simulated output. 7. The hydropower simulation system of the seepage-equivalent seepage resistance method in tight oil reservoirs as claimed in claim 6, wherein in the hydropower simulation system, the simulated wells are made of staged fracturing synchronous injection-production wells horizontal wells made of copper Model.

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