An oil extraction method using nanomotors

Abstract

The present invention relates to the technical field of oil extraction, and particularly to an oil extraction method using nano-motors, comprising: obtaining geological parameters of a target reservoir area and characteristic parameters of the nano-motors; constructing a reservoir-nano-motor coupling model based on the geological parameters and the characteristic parameters, and determining an initial injection speed and an initial injection pressure of the nano-motors; injecting the nano-motors into the target reservoir area based on the initial injection speed and the initial injection pressure, and detecting initial behavior characteristics of the nano-motors during the initial injection process; determining an injection method for a key injection process based on the initial behavior characteristics of the nano-motors within a preset time period; detecting key behavior characteristics of the nano-motors during the key injection process, and determining whether to adjust the injection method based on the key behavior characteristics. The present invention can improve the injection efficiency and distribution uniformity of the nano-motors.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and particularly to an oil extraction method using nanomotors. Background Art

[0002] Most of the oil resources in our country are continental oilfields, and the permeability of oil and gas wells in oilfields is relatively low, making oil extraction relatively difficult. Traditional oilfield exploitation can be divided into primary oil recovery, secondary oil recovery, and tertiary oil recovery. In the primary oil recovery stage, oil usually gushes out spontaneously under the action of formation pressure or is pumped out using a conventional pump. When the formation pressure is insufficient, the formation pressure is supplemented by means of water injection or non-miscible gas injection, and this stage is called the secondary oil recovery stage. However, as the development time prolongs, the water cut of the formation increases, the distribution of remaining oil becomes more dispersed, and the efficiency of secondary oil recovery gradually decreases. In order to further improve the recovery rate, tertiary recovery technology has emerged.

[0003] The core of traditional tertiary recovery technology is to improve the interaction between oil, gas, water, and rock by injecting chemicals (such as polymers, surfactants, etc.), gases (such as carbon dioxide, nitrogen, etc.) into the oil reservoir or by using microorganisms, etc., so as to "wash" more crude oil out of the rock pores. However, these traditional tertiary recovery methods have relatively high technical requirements. While increasing the recovery rate, they may cause damage to the oil reservoir, such as changing the physical properties of the rock or causing formation plugging, affecting the long-term stability of the oil reservoir, and may also cause pollution to the oil reservoir and the surrounding environment. On the other hand, in some complex oil reservoirs, the effect is limited when dealing with the remaining oil in the microchannel structure, and it is difficult to achieve efficient displacement.

[0004] As a new type of tertiary oil recovery technology, nanomotors have unique physical and chemical properties to improve the crude oil recovery rate. Nanomotors move in the pores of the oil reservoir, changing the wettability of the rock surface, converting the oil-wet surface into a water-wet surface. This process can effectively strip the oil film in the rock pores, making the crude oil easier to be displaced. Nanomotors can enter the micro-nano pores that are difficult to reach by traditional oil displacement technologies, capture and carry the remaining oil droplets. However, currently, when using nanomotors for oil extraction, restricted by the pore structure of the oil reservoir, especially under complex geological conditions, nanomotors may be adsorbed or plugged, resulting in low injection efficiency and it is difficult to ensure the uniformity of nanomotors after being injected into the oil reservoir. Summary of the Invention

[0005] Therefore, the present invention provides an oil extraction method using nanomotors to overcome the problems of low injection efficiency of nanomotors and difficulty in ensuring the uniformity of nanomotors after being injected into the oil reservoir in the prior art.

[0006] To achieve the above object, the present invention provides an oil extraction method using nanomotors, including:

[0007] Step S1: Obtain the geological parameters of the target reservoir area and the characteristic parameters of the nanomotors. Among them, the geological parameters include reservoir permeability, reservoir porosity, crude oil viscosity, reservoir pressure, and reservoir temperature, and the characteristic parameters include nanomotor concentration, nanomotor size, and nanomotor viscosity;

[0008] Step S2: Based on the geological parameters and the characteristic parameters, construct a reservoir-nanomotor coupling model, and determine the initial injection velocity and initial injection pressure of the nanomotors;

[0009] Step S3: Inject the nanomotors into the target reservoir area based on the initial injection velocity and the initial injection pressure, and detect the initial behavioral characteristics of the nanomotors during the initial injection process, including moving speed, movement trajectory, distribution range, and aggregation area;

[0010] Step S4: Determine the injection method for the key injection process based on the initial behavioral characteristics of the nanomotors within a preset time period;

[0011] Among them, determine the continuous injection pressure / continuous injection velocity corresponding to the continuous injection method based on the distribution range and the aggregation area;

[0012] And determine the intermittent injection pressure and / or intermittent injection velocity and intermittent time corresponding to the intermittent injection method based on the moving speed and the distribution range;

[0013] Step S5: Detect the key behavioral characteristics of the nanomotors during the key injection process, and determine whether to adjust the injection method based on the key behavioral characteristics.

[0014] Further, in the step S2, it includes:

[0015] Step S21: Based on the geological parameters, construct a reservoir fluid flow model of the target reservoir area;

[0016] Step S22: Based on the characteristic parameters, construct a nanomotor motion model;

[0017] Step S23: Based on the reservoir fluid flow model and the nanomotor motion model, construct a reservoir-nanomotor coupling model.

[0018] Further, in the step S2, it includes:

[0019] Step S24: Determine several motion nodes of the nanomotors based on the reservoir-nanomotor coupling model;

[0020] Step S25: Determine the key motion nodes based on each of the motion nodes;

[0021] Step S26: Determine the initial injection speed and initial injection pressure of the nano - motor based on the key motion nodes.

[0022] Further, in the step S4, determine the injection method for the key injection process, including:

[0023] Step S41: Determine the motion eigenvalue based on the motion trajectory of the nano - motor within a preset time period;

[0024] Step S42: Determine the movement eigenvalue based on the moving speed of the nano - motor within a preset time period;

[0025] Step S43: Determine the injection method for the key injection process based on the motion eigenvalue and the movement eigenvalue.

[0026] Further, in the step S43, it includes:

[0027] Compare the motion eigenvalue with a preset motion eigenvalue, and compare the movement eigenvalue with a preset movement eigenvalue, and determine the injection method for the key injection process based on the comparison results.

[0028] Further, in the step S4, determine the continuous injection pressure / continuous injection speed corresponding to the continuous injection method based on the distribution range and the aggregation area, including:

[0029] Step S44: Determine the key aggregation area of the nano - motor based on the distribution range and the aggregation area of the nano - motor within a preset time period;

[0030] Step S45: Determine the injection pressure and injection speed corresponding to the continuous injection method based on the volume of the key aggregation area and the distribution range.

[0031] Further, in the step S45, it includes:

[0032] If the ratio of the volume of the key aggregation area to the total volume of the distribution range is greater than a first preset ratio, adjust the injection pressure corresponding to the continuous injection method to obtain the continuous injection pressure;

[0033] If the ratio of the volume of the key aggregation area to the total volume of the distribution range is less than a second preset ratio, adjust the injection speed corresponding to the continuous injection method to obtain the continuous injection speed;

[0034] Wherein, the first preset ratio is greater than the second preset ratio.

[0035] Further, in the step S4, determining the intermittent injection pressure and / or intermittent injection speed corresponding to the intermittent injection mode based on the moving speed and the distribution range includes:

[0036] Step S46, determining a first comparison value based on the change in the moving speed of the nano-motor within a preset time period;

[0037] Step S47, determining a second comparison value based on the distribution range of the nano-motor within a preset time period;

[0038] Step S48, determining the injection pressure and injection speed corresponding to the intermittent injection mode based on the first comparison value and the second comparison value.

[0039] Further, in the step S48, it includes:

[0040] If the first comparison value is greater than a first preset comparison value, adjusting the injection speed corresponding to the intermittent injection mode to obtain the intermittent injection speed;

[0041] If the second comparison value is less than a second preset comparison value, adjusting the injection pressure corresponding to the intermittent injection mode to obtain the intermittent injection pressure.

[0042] Further, in the step S5, it includes:

[0043] Determining whether to adjust the injection mode based on the comparison result between the initial behavior characteristics and the key behavior characteristics.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows. The present invention constructs a reservoir-nano-motor coupling model based on the geological parameters of the target reservoir area and the characteristic parameters of the nano-motor, thereby determining the initial injection speed and initial injection pressure of the nano-motor, making the initial injection process of the nano-motor adapt to the geological conditions of the reservoir and its own characteristics, which is beneficial to its effective movement in the reservoir pores and improves the injection efficiency of the nano-motor. By detecting the initial behavior characteristics of the nano-motor during the initial injection process and determining the injection mode of the key injection process, the precise control of the oil displacement process of the nano-motor is realized, which can make the distribution and movement of the nano-motor in the reservoir more in line with the reservoir exploitation requirements, avoid the excessive aggregation of the nano-motor at the injection end, and improve the distribution uniformity of the nano-motor. During the key injection process, continuously detecting the key behavior characteristics of the nano-motor and determining whether to adjust the injection mode accordingly enables the entire exploitation process to be optimized in real time according to the actual situation. This dynamic adjustment mechanism can adapt to the changes in reservoir conditions and the changes in the state of the nano-motor itself during the reservoir exploitation process, always maintaining the best working state of the nano-motor in the reservoir and further improving the exploitation efficiency and recovery rate.

[0045] Furthermore, by separately constructing a reservoir fluid flow model and a nanomotor motion model, the present invention can describe in detail the flow law of the fluid in the reservoir and the motion characteristics of the nanomotor therein. Then, by coupling the two, a reservoir-nanomotor coupling model is obtained, which can simulate the motion of the nanomotor in the reservoir under different geological parameters and nanomotor characteristic parameters, providing a theoretical basis for determining the initial injection velocity and initial injection pressure of the nanomotor in the subsequent stage.

[0046] Furthermore, the present invention can determine several motion nodes of the nanomotor based on the reservoir-nanomotor coupling model. These nodes reflect the states of the nanomotor at different positions in the reservoir. By further screening out the key motion nodes, the positions of great significance of the nanomotor in the reservoir can be clarified, enabling a clearer understanding of the motion path of the nanomotor in the reservoir. Determining the initial injection velocity and initial injection pressure based on the key motion nodes can ensure that the nanomotor moves along the expected path, thereby optimizing the overall motion plan of the nanomotor in the reservoir and improving the effectiveness of its distribution in the reservoir and the injection efficiency of the nanomotor.

[0047] Furthermore, the motion trajectory of the present invention can show the spatial movement path of the nanomotor in the reservoir. The motion characteristic values determined therefrom can reflect its motion information, and the moving velocity directly reflects the variation law of the velocity of the nanomotor in the reservoir fluid. By synthesizing the motion characteristic values and the moving characteristic values, a comprehensive understanding of the behavior of the nanomotor in the reservoir can be obtained, providing an accurate basis for determining the injection method, thereby improving the injection efficiency and distribution uniformity of the nanomotor.

[0048] Furthermore, the present invention determines the key aggregation region of the nanomotor based on the distribution range and aggregation region of the nanomotor within a preset time period, enabling the accurate positioning of the key aggregation region. Adjusting the injection pressure and injection velocity corresponding to the continuous injection method according to the distribution range and key aggregation region of the nanomotor can optimize the overall distribution of the nanomotor in the reservoir and improve the injection efficiency of the nanomotor.

[0049] Furthermore, the change situation of the moving velocity and the distribution range of the nanomotor of the present invention are important indicators reflecting its motion state and action effect in the reservoir. By determining the injection pressure and velocity under the intermittent injection method through these two indicators, the injection process can be made more in line with the actual situation of the nanomotor in the reservoir, flexibly adapting to the dynamic changes inside the reservoir, and improving the distribution uniformity of the nanomotor.

[0050] Furthermore, the initial behavior characteristics of the present invention reflect the performance of the nanomotor in the initial injection stage, while the key behavior characteristics reflect its state in subsequent key stages. By comparing the two, the behavioral changes of the nanomotor can be detected in a timely manner, thereby determining whether it is necessary to adjust the injection method, improving the accuracy and real-time performance of the determination, and thus enhancing the oil displacement efficiency and recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a flowchart of the oil recovery method using a nanomotor according to an embodiment of the present invention;

[0052] Figure 2 is a logic judgment diagram for determining the injection method in the key injection process according to an embodiment of the present invention;

[0053] Figure 3 is a logic judgment diagram for determining whether to adjust the injection pressure and injection speed corresponding to the continuous injection method according to an embodiment of the present invention;

[0054] Figure 4 is a logic judgment diagram for determining whether to adjust the injection pressure and injection speed corresponding to the intermittent injection method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] In order to make the objectives and advantages of the present invention more clear, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0057] Please refer to Figure 1 as shown, which is a flowchart of the oil recovery method using a nanomotor according to an embodiment of the present invention; an embodiment of the present invention provides an oil recovery method using a nanomotor, including:

[0058] Step S1, obtaining the geological parameters of the target reservoir area and the characteristic parameters of the nanomotor, wherein the geological parameters include reservoir permeability, reservoir porosity, crude oil viscosity, reservoir pressure, and reservoir temperature, and the characteristic parameters include nanomotor concentration, nanomotor size, and nanomotor viscosity;

[0059] It should be noted that those skilled in the art know that any device and method capable of detecting the geological parameters of the target reservoir area and the characteristic parameters of the nanomotor in the prior art fall within the protection scope of the present invention and will not be elaborated herein.

[0060] Step S2: Based on the geological parameters and the characteristic parameters, construct a reservoir-nanomotor coupling model, and determine the initial injection velocity and initial injection pressure of the nanomotor;

[0061] Specifically, in the step S2, it includes:

[0062] Step S21: Based on the geological parameters, construct a reservoir fluid flow model for the target reservoir area;

[0063] Step S22: Based on the characteristic parameters, construct a nanomotor motion model;

[0064] Step S23: Based on the reservoir fluid flow model and the nanomotor motion model, construct a reservoir-nanomotor coupling model.

[0065] In a specific embodiment, assume that the reservoir is a porous medium, the fluid in the reservoir is a single-phase incompressible fluid, and the seepage process in the reservoir is in a steady state or quasi-steady state. Based on Darcy's law, seepage mechanics, and heat transfer theory, data fitting is carried out to obtain the corresponding relational expressions respectively: Integrate them to construct a reservoir fluid flow model in the Cartesian coordinate system (x direction): where v is the fluid seepage velocity vector, with the unit of m / s, k is the reservoir permeability, with the unit of m 2 , μ is the viscosity of crude oil, with the unit of Pa·s, is the pressure gradient vector, with the unit of Pa / m, the negative sign indicates that the fluid flows from the high-pressure area to the low-pressure area, Φ is the reservoir porosity, T is the reservoir temperature, with the unit of °C, T0 is the reference temperature, with the unit of °C, μ0 is the viscosity of crude oil at the reference temperature, with the unit of Pa·s, u is the fluid flow velocity, with the unit of m / s, b is a constant related to the properties of crude oil, which can be set according to the actual situation of crude oil, is the change rate of the formation pressure in the x direction. The reservoir fluid flow model can be solved by numerical methods, such as the finite difference method, the finite element method, or the finite volume method. Taking the finite difference method as an example, the reservoir area is discretized into grids, the partial derivatives are approximated by difference forms, the equation is transformed into an algebraic equation set, and then the algebraic equation set is solved iteratively to obtain the pressure values at each grid node in the reservoir, and then the fluid flow velocity is calculated according to the above formula.

[0066] It can be understood that assuming the nanomotor is a spherical particle, based on Stokes' law, Brownian motion law, Newton's second law, and Fick's law, data fitting is carried out to obtain the corresponding relational expressions respectively: F d = 6π×μ×r×v d , where F dWhen the nanomotor moves in a fluid, the viscous drag it experiences, with the unit of N, r is the radius of the nanomotor, with the unit of m, v d is the movement speed of the nanomotor relative to the fluid, D is the diffusion coefficient corresponding to the Brownian motion of the nanomotor, k B is the Boltzmann constant, with the unit of J / K, T d is the absolute temperature, with the unit of K, m is the mass of the nanomotor, F 外力 is the external force, with the unit of N, F 布朗 is the Brownian force, with the unit of N, is the concentration gradient of the nanomotor, with the unit of g / L, and the negative sign indicates that the nanomotor will diffuse from the high-concentration region to the low-concentration region. J is the diffusion flux of the nanomotor, with the unit of g / (m 2 ·s), t is the time, with the unit of s. Integrating them, a nanomotor motion model under one-dimensional conditions (x direction) is constructed: is the change rate of the nanomotor concentration with time, represents the diffusion of the nanomotor caused by Brownian motion, represents the change in concentration caused by the macroscopic motion of the nanomotor (carried by the fluid or its own motion). Numerical methods can be used to solve it, such as the finite difference method, the finite element method, etc. Taking the finite difference method as an example, the space and time are discretized, the partial derivatives are approximated by difference forms, and the equation is transformed into an algebraic equation system. By iterative solution, the nanomotor concentration distribution at different times and different positions can be obtained, and then the motion situation of the nanomotor can be analyzed.

[0067] It should be noted that the present application does not make specific limitations on the morphological structure of the nanomotor.

[0068] It can be understood that the reservoir fluid flow model describes the flow law of fluids in the reservoir pores, while the nanomotor motion model depicts the motion behavior of nanomotors in the fluid. Based on the reservoir fluid flow model and the nanomotor motion model, constructing a reservoir-nanomotor coupling model can identify the factors influencing each other between the two and reasonably correlate these factors in the model. The reservoir-nanomotor coupling model is a set of complex partial differential equations, which can be solved numerically, such as the finite element method or the finite volume method. Taking the finite element method as an example, the reservoir area is discretized into a finite number of elements, and the equations within each element are discretized. By constructing a coefficient matrix and solving a system of linear equations, physical quantities such as the reservoir fluid velocity, pressure, nanomotor concentration, and velocity at each point in the reservoir at different times are obtained. The reservoir-nanomotor coupling model is verified using actual reservoir data or carefully designed experimental data. By comparing the results of the nanomotor distribution, reservoir fluid pressure, flow rate, etc. predicted by the model with the actual measured values, if there are deviations, analyze the reasons for the deviations, check whether the model assumptions, parameter values, etc. are reasonable, and adjust and optimize the model until the model prediction results match the actual situation.

[0069] By separately constructing a reservoir fluid flow model and a nanomotor motion model, the present invention can describe in detail the flow law of fluids in the reservoir and the motion characteristics of nanomotors therein, and then couple the two to obtain a reservoir-nanomotor coupling model, which can simulate the motion of nanomotors in the reservoir under different geological parameters and nanomotor characteristic parameters, providing a theoretical basis for determining the initial injection velocity and initial injection pressure of nanomotors subsequently.

[0070] Specifically, in the step S2, it includes:

[0071] Step S24, determining a number of motion nodes of the nanomotor based on the reservoir-nanomotor coupling model;

[0072] Step S25, determining key motion nodes based on each of the motion nodes;

[0073] Step S26, determining the initial injection velocity and initial injection pressure of the nanomotor based on the key motion nodes.

[0074] In a specific embodiment, the movement of the nano-motor during the initial injection process is simulated based on the reservoir-nano-motor coupling model. The position at the moment when the movement state of the nano-motor changes significantly is extracted as a movement node. Each movement node includes the position coordinates of the nano-motor and its movement state at that moment. The movement nodes are screened based on specific regions in the reservoir (such as crude oil enrichment areas, low-permeability regions, etc.), positions where significant changes in the movement state occur, and specific time points (such as the moment when the nano-motor starts to take effect, the moment when the maximum oil displacement effect is achieved, etc.). The key movement nodes can be determined by calculating relevant parameters of each movement node (such as the distance from the position to the target area, the rate of change of speed, etc.) and comparing them with the screening criteria. For example, if the screening criterion is that the node where the nano-motor reaches within a certain range of the crude oil enrichment area is a key movement node, then calculate the distance between each movement node and the crude oil enrichment area, and mark the nodes that meet the condition as key movement nodes. It can be understood that by analyzing the selected key movement nodes, the conditions that the nano-motor needs to meet to reach these nodes are determined. For example, analyze the speed and position requirements of the nano-motor at the key movement nodes, and the reservoir resistance that needs to be overcome during the movement process. If the key movement node is located in the low-permeability region of the reservoir, then the nano-motor needs to have sufficient power to reach this region, which puts higher requirements on the initial injection speed and initial injection pressure. Based on the requirements of the key movement nodes, an objective function is established to determine the constraint conditions that the initial injection speed and initial injection pressure need to meet. An optimization algorithm (such as a genetic algorithm, a particle swarm algorithm, etc.) is used to solve the objective function. On the premise of meeting the constraint conditions, the initial injection speed and initial injection pressure that make the objective function optimal are found. By continuously adjusting the values of the initial injection speed and initial injection pressure, the movement trajectory of the nano-motor in the reservoir is calculated, and the advantages and disadvantages of each parameter combination are evaluated according to the objective function. Finally, the optimal initial injection speed and initial injection pressure are obtained.

[0075] The present invention can determine a number of movement nodes of the nano-motor based on the reservoir-nano-motor coupling model. These nodes reflect the states of the nano-motor at different positions in the reservoir. By further screening out the key movement nodes, the positions of great significance of the nano-motor in the reservoir can be clarified, enabling a clearer understanding of the movement path of the nano-motor in the reservoir. Determining the initial injection speed and initial injection pressure based on the key movement nodes can ensure that the nano-motor moves along the expected path, thereby optimizing the overall movement plan of the nano-motor in the reservoir, improving the effectiveness of its distribution in the reservoir, and enhancing the injection efficiency of the nano-motor.

[0076] Step S3: Inject the nanomotors into the target reservoir area based on the initial injection speed and the initial injection pressure, and detect the initial behavioral characteristics of the nanomotors during the initial injection process, including the moving speed, movement trajectory, distribution range, and aggregation area;

[0077] It should be noted that those skilled in the art are aware that any device and method in the prior art capable of detecting the behavioral characteristics of nanomotors during the injection process into the target reservoir area fall within the protection scope of the present invention and will not be elaborated herein.

[0078] Step S4: Determine the injection method for the key injection process based on the initial behavioral characteristics of the nanomotors within a preset time period, including the continuous injection method and the intermittent injection method;

[0079] Among them, determine the continuous injection pressure / continuous injection speed corresponding to the continuous injection method based on the distribution range and the aggregation area;

[0080] And determine the intermittent injection pressure and / or intermittent injection speed and intermittent time corresponding to the intermittent injection method based on the moving speed and the distribution range;

[0081] Please refer to Figure 2 As shown, it is a logic judgment diagram for determining the injection method of the key injection process in an embodiment of the present invention; specifically, in the step S4, determine the injection method of the key injection process, including:

[0082] Step S41: Determine the motion characteristic value based on the movement trajectory of the nanomotors within a preset time period;

[0083] Step S42: Determine the movement characteristic value based on the moving speed of the nanomotors within a preset time period;

[0084] Step S43: Determine the injection method for the key injection process based on the motion characteristic value and the movement characteristic value.

[0085] Specifically, in the step S43, it includes:

[0086] Compare the motion characteristic value with a preset motion characteristic value, and compare the movement characteristic value with a preset movement characteristic value, and determine the injection method for the key injection process based on the comparison results.

[0087] In a specific embodiment, the motion characteristic value is determined based on the number of branch trajectories in the motion trajectory of the nanomotor within a preset time period (a motion trajectory with the distance from the trajectory end point to the trajectory bifurcation point greater than the set distance is determined as a branch trajectory) or the frequency of significant changes in the motion direction (the included angle between the velocity vectors of adjacent trajectory points is greater than the set angle), and the movement characteristic value is determined based on the standard deviation of the moving speed of the nanomotor within a preset time period.

[0088] It can be understood that if the motion characteristic value is greater than the preset motion characteristic value and / or the movement characteristic value is less than the preset movement characteristic value, it indicates that the nanomotor can move relatively smoothly in the reservoir, and a continuous injection method can be adopted to improve the injection efficiency of the nanomotor. If the motion characteristic value is less than or equal to the preset motion characteristic value and the movement characteristic value is greater than or equal to the preset movement characteristic value, it indicates that the movement of the nanomotor in the reservoir is subject to more interference and the movement is unstable. An intermittent injection method can be adopted to give the nanomotor enough time to adjust its position and direction in the reservoir, reduce local aggregation and movement chaos caused by continuous injection, and improve the distribution uniformity of the nanomotor.

[0089] In implementation, the actual implementer can set the set distance, set angle, preset motion characteristic value, and preset movement characteristic value according to the actual situation or based on the motion trajectories of the nanomotors that have passed the qualification test in historical data. Preferably, the value range of the set distance is set to 0.5 m to 1.0 m, the value range of the set angle is set to 30° to 50°, the value range of the preset motion characteristic value is set to 5 to 8, the value range of the preset movement characteristic value is set to 1 to 3, and the value range of the preset time period is set to 30 min to 50 min.

[0090] The motion trajectory of the present invention can show the spatial movement path of the nanomotor in the reservoir. The motion characteristic value determined therefrom can reflect its motion information, and the moving speed directly reflects the change law of the speed of the nanomotor in the reservoir fluid. Combining the motion characteristic value and the movement characteristic value can comprehensively understand the behavior performance of the nanomotor in the reservoir, provide an accurate basis for determining the injection method, and thus improve the injection efficiency and distribution uniformity of the nanomotor.

[0091] Please refer to Figure 3 as shown, which is a logic judgment diagram for determining whether to adjust the injection pressure and injection speed of the continuous injection method in the embodiment of the present invention; specifically, in the step S4, determining the continuous injection pressure / continuous injection speed corresponding to the continuous injection method based on the distribution range and the aggregation area includes:

[0092] Step S44, determining the key aggregation area of the nanomotor based on the distribution range and the aggregation area of the nanomotor within a preset time period;

[0093] Step S45: Determine the injection pressure and injection speed corresponding to the continuous injection method based on the volume of the key aggregation region and the distribution range.

[0094] Specifically, in the step S45, it includes:

[0095] If the ratio of the volume of the key aggregation region to the total volume of the distribution range is greater than the first preset ratio, adjust the injection pressure corresponding to the continuous injection method to obtain the continuous injection pressure;

[0096] If the ratio of the volume of the key aggregation region to the total volume of the distribution range is less than the second preset ratio, adjust the injection speed corresponding to the continuous injection method to obtain the continuous injection speed;

[0097] If the ratio of the volume of the key aggregation region to the total volume of the distribution range is less than or equal to the first preset ratio and greater than or equal to the second preset ratio, do not adjust the injection pressure and injection speed corresponding to the continuous injection method;

[0098] Wherein, the first preset ratio is greater than the second preset ratio.

[0099] In a specific embodiment, the distribution range is the largest region enclosed by the movement trajectories of the nanomotors, the aggregation region is the region where the number of nanomotors per unit volume is greater than the first preset number. Calculate the volume of each aggregation region and its volume proportion within the nanomotor distribution range, and determine the key aggregation region as the aggregation region with the largest proportion.

[0100] It can be understood that if the ratio of the volume of the key aggregation region to the total volume of the distribution range is greater than the first preset ratio, it indicates that the volume of the key aggregation region is relatively large. To avoid excessive aggregation of nanomotors in a local area resulting in blockage, enable the nanomotors to overcome the resistance brought by narrow pores and tortuous channels, smoothly travel through the reservoir pores, and expand their migration range within the reservoir, the injection pressure corresponding to the continuous injection method should be increased. Determine the continuous pressure adjustment amount based on the product of the ratio of the volume of the key aggregation region to the total volume of the distribution range and the initial injection pressure, then the continuous injection pressure is the sum of the initial injection pressure and the continuous pressure adjustment amount.

[0101] It can be understood that if the ratio of the volume of the key aggregation region to the total volume of the distribution range is less than the second preset ratio, it indicates that the aggregation regions are relatively dispersed. To enable the nanomotors to be evenly distributed in the target reservoir area, it is necessary to appropriately increase the injection speed. Determine the continuous speed adjustment amount based on the product of the ratio of the volume of the key aggregation region to the total volume of the distribution range and the initial injection speed, then the continuous injection speed is the sum of the initial injection speed and the continuous speed adjustment amount.

[0102] It is understandable that if the ratio of the volume of the key aggregation area to the total volume of the distribution range is less than or equal to the first preset ratio and greater than or equal to the second preset ratio, the injection pressure and injection speed corresponding to the continuous injection mode are not adjusted, and the initial injection pressure and initial injection speed are continued for the injection in the continuous injection mode.

[0103] In implementation, the actual implementer can set the first preset ratio and the second preset ratio according to the actual situation or based on the aggregation area and distribution range of the nano-motors passing the qualification test in the initial injection process in historical data. Preferably, the value range of the first preset ratio is set to 0.01 - 0.1, and the value range of the second preset ratio is set to 0.003 - 0.005.

[0104] The present invention determines the key aggregation area of the nano-motors based on the distribution range and aggregation area of the nano-motors within a preset time period, can achieve precise positioning of the key aggregation area, and adjusts the injection pressure and injection speed corresponding to the continuous injection mode according to the distribution range and key aggregation area of the nano-motors, which can optimize the overall distribution of the nano-motors in the reservoir and improve the injection efficiency of the nano-motors.

[0105] Please refer to Figure 4 as shown, which is a logical judgment diagram for determining whether to adjust the injection pressure and injection speed corresponding to the intermittent injection mode in the embodiment of the present invention; specifically, in the step S4, determining the intermittent injection pressure and / or intermittent injection speed corresponding to the intermittent injection mode based on the moving speed and the distribution range includes:

[0106] Step S46, determining a first comparison value based on the change situation of the moving speed of the nano-motors within a preset time period;

[0107] Step S47, determining a second comparison value based on the distribution range of the nano-motors within a preset time period;

[0108] Step S48, determining the injection pressure and injection speed corresponding to the intermittent injection mode based on the first comparison value and the second comparison value.

[0109] Specifically, in the step S48, it includes:

[0110] If the first comparison value is greater than the first preset comparison value, adjust the injection speed corresponding to the intermittent injection mode to obtain the intermittent injection speed;

[0111] If the second comparison value is less than the second preset comparison value, adjust the injection pressure corresponding to the intermittent injection mode to obtain the intermittent injection pressure.

[0112] In a specific embodiment, a first comparison value is determined based on the ratio of the minimum moving speed to the maximum moving speed of the nanomotor within a preset time period, and a second comparison value is determined based on the ratio of the distribution range of the nanomotor to the standard distribution range within the preset time period.

[0113] It can be understood that if the first comparison value indicates the degree of fluctuation of the moving speed of the nanomotor, the closer the first comparison value is to 1, the more stable the moving speed of the nanomotor is. The smaller the first comparison value is, the greater the fluctuation of the moving speed of the nanomotor is. If the first comparison value is greater than the first preset comparison value, it indicates that the migration of the nanomotor in the target reservoir area is relatively smooth. The injection efficiency of the nanomotor can be improved by increasing the injection speed corresponding to the intermittent injection method; the intermittent speed adjustment amount is determined according to the product of the first comparison value and the initial injection speed, and the intermittent injection speed is determined according to the product of the initial injection speed and the intermittent speed adjustment amount.

[0114] It can be understood that if the second comparison value is less than the second preset comparison value, it indicates that the gap between the distribution range of the nanomotor and the standard distribution range is relatively large. The gap with the standard distribution range can be reduced and the distribution uniformity of the nanomotor can be improved by increasing the injection pressure corresponding to the intermittent injection method. The intermittent pressure adjustment amount is determined according to the product of the second comparison value and the initial injection pressure, and the intermittent injection pressure is determined according to the product of the initial injection pressure and the intermittent pressure adjustment amount.

[0115] It can be understood that if the first comparison value is less than or equal to the first preset comparison value and the second comparison value is greater than or equal to the second preset comparison value, the injection pressure and injection speed corresponding to the intermittent injection method are not adjusted, and the injection of the intermittent injection method is continued with the initial injection pressure and the initial injection speed.

[0116] In practice, the actual implementer can set the first preset comparison value, the second preset comparison value and the standard distribution range according to the actual situation or based on the moving speed and distribution range of the nanomotor passing the qualification test in the initial injection process in the historical data, or set the first preset comparison value, the second preset comparison value and the standard distribution range based on the simulation of the reservoir-nanomotor coupling model. Preferably, the value range of the first preset comparison value is set to 0.5-0.7, the value range of the second preset comparison value is set to 0.2-0.4, and the value range of the standard distribution range is set to 0.1m 3 ~0.3m 3 。

[0117] It can be understood that the intermittent time can be determined based on the first comparison value B1, the first preset comparison value YB1, the second comparison value B2, the second preset comparison value YB2 and the preset time period yt, and the intermittent time

[0118] The variation in the moving speed and the distribution range of the nanomotors of the present invention are important indicators reflecting their motion states and acting effects in the reservoir. By determining the injection pressure and speed under the intermittent injection mode through these two indicators, the injection process can be made more in line with the actual situation of the nanomotors in the reservoir, flexibly adapting to the dynamic changes inside the reservoir, and improving the distribution uniformity of the nanomotors.

[0119] Step S5: Detect the key behavioral characteristics of the nanomotors during the key injection process, and determine whether to adjust the injection mode based on the key behavioral characteristics.

[0120] Specifically, in the step S5, it includes:

[0121] Determine whether to adjust the injection mode based on the comparison result between the initial behavioral characteristics and the key behavioral characteristics.

[0122] In a specific embodiment, based on the initial behavioral characteristics Y1, Y2, …, Y j , …, Y m and the key behavioral characteristics E1, E2, …, E j , …, E m determine the feature comparison value TB = (∑ m j＝1 Y j × E j ) / (sqrt(∑ m j＝1 (Y j ) 2 ) × sqrt(∑ m j＝1 (E j ) 2 )); sqrt() is a preset square root determination function, j = 1, 2, …, m, where m is the number of behavioral characteristics. If the feature comparison value is greater than the preset feature comparison value, it is determined that there is no need to adjust the injection mode. If the feature comparison value is less than or equal to the preset feature comparison value, it is determined that it is necessary to adjust the injection mode, and the injection mode is re-determined through the detected key behavioral characteristics.

[0123] In implementation, the actual implementers can set the preset feature comparison value according to the actual situation or based on the comparison result between the initial behavioral characteristics and the key behavioral characteristics that pass the qualification test in the historical data. Preferably, the value range of the preset feature comparison value is set to 0.7 - 0.9.

[0124] The initial behavioral characteristics of the present invention reflect the performance of the nanomotor in the initial injection stage, while the key behavioral characteristics reflect its state in subsequent key stages. By comparing the two, the behavioral changes of the nanomotor can be detected in a timely manner, and based on this, it can be determined whether the injection method needs to be adjusted, which can improve the accuracy and real-time performance of the determination, thereby improving the oil displacement efficiency and recovery rate.

[0125] The present invention constructs a reservoir-nanomotor coupling model based on the geological parameters of the target reservoir area and the characteristic parameters of the nanomotor, thereby determining the initial injection speed and initial injection pressure of the nanomotor, making the initial injection process of the nanomotor adapt to the geological conditions of the reservoir and its own characteristics, which is beneficial to its effective movement in the reservoir pores and improves the injection efficiency of the nanomotor. By detecting the initial behavioral characteristics of the nanomotor during the initial injection process, the injection method for the key injection process is determined, realizing the precise control of the oil displacement process of the nanomotor, enabling the distribution and movement of the nanomotor in the reservoir to better meet the reservoir exploitation requirements, avoiding excessive aggregation of the nanomotor at the injection end, and improving the distribution uniformity of the nanomotor. During the key injection process, the key behavioral characteristics of the nanomotor are continuously detected, and based on this, it is determined whether the injection method needs to be adjusted, so that the entire exploitation process can be optimized in real time according to the actual situation. This dynamic adjustment mechanism can adapt to the changes in reservoir conditions and the changes in the state of the nanomotor itself during the reservoir exploitation process, always maintaining the best working state of the nanomotor in the reservoir, and further improving the exploitation efficiency and recovery rate.

[0126] So far, the technical solution of the present invention has been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An oil extraction method using a nanomotor, characterized in that, Including: Step S1: Obtain the geological parameters of the target reservoir area and the characteristic parameters of the nanomotors. Among them, the geological parameters include reservoir permeability, reservoir porosity, crude oil viscosity, reservoir pressure, and reservoir temperature, and the characteristic parameters include nanomotor concentration, nanomotor size, and nanomotor viscosity; Step S2: Based on the geological parameters and the characteristic parameters, construct a reservoir-nanomotor coupling model, and determine the initial injection velocity and initial injection pressure of the nanomotors; Step S3: Inject the nanomotors into the target reservoir area based on the initial injection velocity and the initial injection pressure, and detect the initial behavior characteristics of the nanomotors during the initial injection process, including moving speed, movement trajectory, distribution range, and aggregation area; Step S4: Determine the injection method for the key injection process based on the initial behavior characteristics of the nanomotors within a preset time period; Among them, determine the continuous injection pressure / continuous injection velocity corresponding to the continuous injection method based on the distribution range and the aggregation area; And determine the intermittent injection pressure and / or intermittent injection velocity and intermittent time corresponding to the intermittent injection method based on the moving speed and the distribution range; Step S5: Detect the key behavior characteristics of the nanomotors during the key injection process, and determine whether to adjust the injection method based on the key behavior characteristics; Among them, in step S4, determining the injection method for the key injection process includes: Step S41: Determine the motion characteristic value based on the movement trajectory of the nanomotors within a preset time period; Step S42: Determine the moving characteristic value based on the moving speed of the nanomotors within a preset time period; Step S43: Determine the injection method for the key injection process based on the motion characteristic value and the moving characteristic value; In step S43, it includes: Compare the motion characteristic value with a preset motion characteristic value, and compare the moving characteristic value with a preset moving characteristic value, and determine the injection method for the key injection process based on the comparison results.

2. The oil extraction method using a nano-motor according to claim 1, characterized in that, In step S2, it includes: Step S21: Construct a reservoir fluid flow model of the target reservoir area based on the geological parameters; Step S22: Construct a nanomotor motion model based on the characteristic parameters; Step S23: Construct a reservoir-nanomotor coupling model based on the reservoir fluid flow model and the nanomotor motion model.

3. The oil extraction method using a nano-motor according to claim 2, characterized in that, In step S2, it includes: Step S24: Determine several motion nodes of the nanomotors based on the reservoir-nanomotor coupling model; Step S25: Determine the key motion nodes based on each of the motion nodes; Step S26: Determine the initial injection velocity and initial injection pressure of the nanomotors based on the key motion nodes.

4. The oil extraction method using a nano-motor according to claim 3, characterized in that, In step S4, determining the continuous injection pressure / continuous injection velocity corresponding to the continuous injection method based on the distribution range and the aggregation area includes: Step S44: Determine the key aggregation area of the nanomotors based on the distribution range and the aggregation area of the nanomotors within a preset time period; Step S45: Determine the injection pressure and injection speed corresponding to the continuous injection mode based on the volume of the key aggregation region and the distribution range.

5. The oil extraction method using a nano-motor according to claim 4, characterized in that, In the step S45, it includes: If the ratio of the volume of the key aggregation region to the total volume of the distribution range is greater than a first preset ratio, adjust the injection pressure corresponding to the continuous injection mode to obtain the continuous injection pressure; If the ratio of the volume of the key aggregation region to the total volume of the distribution range is less than a second preset ratio, adjust the injection speed corresponding to the continuous injection mode to obtain the continuous injection speed; Wherein, the first preset ratio is greater than the second preset ratio.

6. The oil extraction method using a nano-motor according to claim 5, characterized in that, In the step S4, determining the intermittent injection pressure and / or intermittent injection speed corresponding to the intermittent injection mode based on the moving speed and the distribution range includes: Step S46: Determine a first comparison value based on the change in the moving speed of the nanomotor within a preset time period; Step S47: Determine a second comparison value based on the distribution range of the nanomotor within a preset time period; Step S48: Determine the injection pressure and injection speed corresponding to the intermittent injection mode based on the first comparison value and the second comparison value.

7. The oil extraction method using a nano-motor according to claim 6, characterized in that, In the step S48, it includes: If the first comparison value is greater than a first preset comparison value, adjust the injection speed corresponding to the intermittent injection mode to obtain the intermittent injection speed; If the second comparison value is less than a second preset comparison value, adjust the injection pressure corresponding to the intermittent injection mode to obtain the intermittent injection pressure.

8. The oil extraction method using a nano-motor according to claim 7, characterized in that, In the step S5, it includes: Determine whether it is necessary to adjust the injection mode based on the comparison result between the initial behavior feature and the key behavior feature.

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