Petroleum exploitation method using nano motor

Abstract

The invention relates to the technical field of oil exploitation, in particular to an oil exploitation method using a nano motor, which comprises the following steps: acquiring geological parameters of a target oil reservoir area and characteristic parameters of the nano motor; based on the geological parameters and the characteristic parameters, an oil reservoir-nano motor coupling model is constructed, and the initial injection speed and initial injection pressure of a nano motor are determined; injecting the nano motor into the target oil reservoir area based on the initial injection speed and the initial injection pressure, and detecting initial behavior characteristics of the nano motor in the initial injection process; determining an injection mode of the key injection process based on the initial behavior characteristics of the nano motor in a preset time period; key behavior characteristics of the nano motor in the key injection process are detected, and whether the injection mode needs to be adjusted or not is judged based on the key behavior characteristics. According to the invention, the injection efficiency and the distribution uniformity of the nano motor can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and in particular to an oil extraction method using a nano motor. Background Art

[0002] Most of my country's oil resources are distributed in continental oil fields, and the permeability of oil and gas wells in oil fields is low, making oil extraction relatively difficult. Traditional oil field extraction can be divided into primary oil recovery, secondary oil recovery and tertiary oil recovery. In the primary oil recovery stage, oil is usually produced by self-flowing under the action of formation pressure, or it is pumped out using conventional pumps. When the formation pressure is insufficient, the formation pressure is supplemented by water injection or immiscible gas injection. This stage is called the secondary oil recovery stage. However, as the development time increases, the formation water content increases, the remaining oil distribution becomes more dispersed, and the efficiency of secondary oil recovery gradually decreases. In order to further improve the recovery rate, tertiary recovery technology came into being.

[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.) or using microorganisms into the oil layer, so as to "wash" more crude oil out of the rock pores. However, these traditional tertiary recovery methods have high technical requirements. While improving the recovery rate, they may cause damage to the reservoir, such as changing the physical properties of the rock or causing formation blockage, affecting the long-term stability of the reservoir, and may also pollute the reservoir and the surrounding environment. On the other hand, in some complex reservoirs, the effect is limited when dealing with residual oil in tiny pore structures, 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 crude oil recovery. Nanomotors move in the pores of the reservoir, changing the wettability of the rock surface and converting the oleophilic surface into a hydrophilic surface. This process can effectively strip the oil film in the rock pores, making it easier for crude oil to be displaced. Nanomotors can enter micro-nano pores that are difficult to reach with traditional oil recovery technology, capture and carry remaining oil droplets. However, when using nanomotors for oil extraction, they are currently limited by the pore structure of the reservoir, especially under complex geological conditions. Nanomotors may be adsorbed or blocked, resulting in low injection efficiency and difficulty in ensuring the uniformity of nanomotors after injection into the reservoir. Summary of the invention

[0005] To this end, the present invention provides an oil extraction method using nano motors to overcome the problems in the prior art of low injection efficiency of nano motors and difficulty in ensuring uniformity of nano motors after injection into oil reservoirs.

[0006] To achieve the above object, the present invention provides a method for oil extraction using a nanomotor, comprising:

[0007] Step S1, obtaining geological parameters of the target reservoir area and 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;

[0008] Step S2, constructing a reservoir-nanomotor coupling model based on the geological parameters and the characteristic parameters, and determining an initial injection velocity and an initial injection pressure of the nanomotor;

[0009] Step S3, injecting the nanomotor into the target reservoir area based on the initial injection speed and the initial injection pressure, and detecting the initial behavior characteristics of the nanomotor during the initial injection process, including movement speed, movement trajectory, distribution range and aggregation area;

[0010] Step S4, determining an injection method of a key injection process based on the initial behavior characteristics of the nanomotor within a preset time period;

[0011] Wherein, the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode is determined based on the distribution range and the gathering area;

[0012] and, determining the interval injection pressure and / or interval injection speed and interval time corresponding to the interval injection method based on the moving speed and the distribution range;

[0013] Step S5, detecting key behavior characteristics of the nanomotor during a key injection process, and determining whether the injection method needs to be adjusted based on the key behavior characteristics.

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

[0015] Step S21, constructing a reservoir fluid flow model of the target reservoir area based on the geological parameters;

[0016] Step S22, constructing a nanomotor motion model based on the characteristic parameters;

[0017] Step S23, constructing a reservoir-nanomotor coupling model based on the reservoir fluid flow model and the nanomotor motion model.

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

[0019] Step S24, determining a number of motion nodes of the nanomotor based on the reservoir-nanomotor coupling model;

[0020] Step S25, determining a key motion node based on each of the motion nodes;

[0021] Step S26, determining the initial injection speed and initial injection pressure of the nanomotor based on the key motion nodes.

[0022] Furthermore, in step S4, determining the injection method of the key injection process includes:

[0023] Step S41, determining a motion characteristic value based on the motion trajectory of the nanomotor within a preset time period;

[0024] Step S42, determining a movement characteristic value based on the movement speed of the nanomotor within a preset time period;

[0025] Step S43: determining an injection method of a key injection process based on the motion characteristic value and the movement characteristic value.

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

[0027] The motion characteristic value is compared with a preset motion characteristic value, and the movement characteristic value is compared with a preset movement characteristic value, and an injection method of a key injection process is determined based on the comparison result.

[0028] Further, in the step S4, determining the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode based on the distribution range and the gathering area includes:

[0029] Step S44, determining a key aggregation area of ​​the nanomotor based on the distribution range and aggregation area of ​​the nanomotor within a preset time period;

[0030] Step S45, determining the injection pressure and injection speed corresponding to the continuous injection method based on the volume of the key gathering area and the distribution range.

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

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

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

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

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

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

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

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

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

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

[0041] If the second comparison value is less than the second preset comparison value, the injection pressure corresponding to the interval injection method is adjusted to obtain the interval injection pressure.

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

[0043] Whether the injection mode needs to be adjusted is determined based on the comparison result between the initial behavior feature and the key behavior feature.

[0044] Compared with the prior art, the beneficial effect of the present invention is that 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, so that the initial injection process of the nanomotor is adapted to the geological conditions and self-characteristics of the reservoir, which is conducive to its effective movement in the reservoir pores and improves the injection efficiency of the nanomotor. By detecting the initial behavior characteristics of the nanomotor during the initial injection process, the injection method of the key injection process is determined, and the precise control of the nanomotor oil displacement process is achieved, so that the distribution and movement of the nanomotor in the reservoir can be more in line with the reservoir exploitation requirements, avoiding excessive aggregation of the nanomotor at the injection end, and improving the distribution uniformity of the nanomotor. The key behavior characteristics of the nanomotor are continuously detected during the key injection process, and it is determined whether the injection method needs to be adjusted based on this, 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, and always maintain the best working state of the nanomotor in the reservoir, further improving the exploitation efficiency and recovery rate.

[0045] Furthermore, the present invention can describe in detail the flow law of the fluid in the reservoir and the movement characteristics of the nanomotor therein by separately constructing a reservoir fluid flow model and a nanomotor motion model, and then couple the two to obtain a reservoir-nanomotor coupling model, which can simulate the movement of the nanomotor in the reservoir under different geological parameters and nanomotor characteristic parameters, and provide a theoretical basis for the subsequent determination of the initial injection speed and initial injection pressure of the nanomotor.

[0046] Furthermore, the present invention can determine several motion nodes of the nanomotor based on the reservoir-nanomotor coupling model, and these nodes reflect the states of the nanomotor at different positions in the reservoir. By further screening out key motion nodes, the important positions of the nanomotor in the reservoir can be clearly identified, and a clearer understanding of the motion path of the nanomotor in the reservoir can be obtained. By determining the initial injection speed and the initial injection pressure based on the key motion nodes, it can be ensured that the nanomotor moves along the expected path, thereby optimizing the overall motion planning of the nanomotor in the reservoir, improving the effectiveness of its distribution in the reservoir, and improving 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, and the motion characteristic value determined therefrom can reflect its motion information. The movement speed directly reflects the changing law of the speed of the nanomotor in the reservoir fluid. The comprehensive motion characteristic value and movement characteristic value can fully understand the behavior 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.

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

[0049] Furthermore, the change in movement speed and distribution range of the nanomotor of the present invention are important indicators reflecting its movement state and effect in the oil reservoir. The injection pressure and speed under the interval injection method are determined by these two indicators, which can make the injection process more in line with the actual situation of the nanomotor in the oil reservoir, flexibly adapt to the dynamic changes inside the oil reservoir, and improve the distribution uniformity of the nanomotor.

[0050] Furthermore, the initial behavioral characteristics of the present invention reflect the performance of the nanomotor at the initial stage of injection, while the key behavioral characteristics reflect its status in the subsequent key stages. By comparing the two, the behavioral changes of the nanomotor can be discovered in a timely manner to determine whether the injection method needs to be adjusted. This can improve the accuracy and real-time nature of the judgment, thereby improving oil displacement efficiency and recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A flow chart of a method for oil extraction using nanomotors according to an embodiment of the present invention;

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

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

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

[0055] In order to make the objects and advantages of the present invention more clearly understood, the present invention is 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 are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0057] See also Figure 1 As shown, it is a flow chart of an oil extraction method using a nano motor according to an embodiment of the present invention; an oil extraction method using a nano motor according to an embodiment of the present invention includes:

[0058] Step S1, obtaining geological parameters of the target reservoir area and 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 are aware that any device and method in the prior art that can detect the geological parameters of the target oil reservoir area and the characteristic parameters of the nanomotor falls within the protection scope of the present invention and will not be described in detail here.

[0060] Step S2, constructing a reservoir-nanomotor coupling model based on the geological parameters and the characteristic parameters, and determining an initial injection velocity and an initial injection pressure of the nanomotor;

[0061] Specifically, the step S2 includes:

[0062] Step S21, constructing a reservoir fluid flow model of the target reservoir area based on the geological parameters;

[0063] Step S22, constructing a nanomotor motion model based on the characteristic parameters;

[0064] Step S23, constructing a reservoir-nanomotor coupling model based on the reservoir fluid flow model and the nanomotor motion model.

[0065] In a specific embodiment, it is assumed 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 performed to obtain the corresponding relationship: Integrate them to construct the reservoir fluid flow model in the Cartesian coordinate system (x direction): Where v is the fluid flow velocity vector, in m / s, and k is the reservoir permeability, in m 2 , μ is the viscosity of crude oil, in Pa·s, is the pressure gradient vector, in 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, in °C, T0 is the reference temperature, in °C, μ0 is the crude oil viscosity at the reference temperature, in Pa·s, u is the fluid flow rate, in m / s, b is a constant related to the crude oil properties, which can be set according to the actual situation of the crude oil, is the rate of change of formation pressure in the x direction. Numerical methods can be used to solve the reservoir fluid flow model, 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 in differential form, the equation is converted into a set of algebraic equations, and then the pressure value on each grid node in the reservoir is obtained by iteratively solving the algebraic equations, and then the fluid flow rate is calculated according to the above formula.

[0066] It can be understood that, assuming that the nanomotor is a spherical particle, the data is fitted based on Stokes' law, Brownian motion law, Newton's second law and Fick's law, and the corresponding relationship is obtained respectively: F d =6π×μ×r×v d , Among them, F dis the viscous resistance encountered by the nanomotor when it moves in the fluid, in N, r is the radius of the nanomotor, in m, v d is the 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, in J / K, T d is the absolute temperature in K, m is the mass of the nanomotor, F 外力 is the external force, the unit is N, F 布朗 is the Brownian force, in N, is the nanomotor concentration gradient, in g / L, the negative sign indicates that the nanomotor will diffuse from the high concentration area to the low concentration area, J is the nanomotor diffusion flux, in g / (m 2 ·s), t is time, unit is s, and they are integrated to construct the nanomotor motion model under one-dimensional conditions (x direction): is the rate of change of nanomotor concentration over time, represents the diffusion of nanomotors due to Brownian motion, It represents the concentration change caused by the macroscopic movement of nanomotors (carried by fluid or self-movement), which can be solved by numerical methods, such as finite difference method, finite element method, etc. Taking finite difference method as an example, space and time are discretized, partial derivatives are approximated by differential form, and the equation is converted into a set of algebraic equations. The concentration distribution of nanomotors at different times and positions is obtained by iterative solution, and then the movement of nanomotors is analyzed.

[0067] It should be noted that the present application does not specifically limit the morphological structure of the nanomotor.

[0068] It can be understood that the reservoir fluid flow model describes the flow law of the fluid in the reservoir pores, while the nanomotor motion model describes the movement behavior of the nanomotor in the fluid. Constructing a reservoir-nanomotor coupling model based on the reservoir fluid flow model and the nanomotor motion model can find the factors that influence each other and reasonably associate these factors in the model. The reservoir-nanomotor coupling model is a set of complex partial differential equations that can be solved by numerical methods, 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 units, and the equations in each unit are discretized. By constructing a coefficient matrix and solving a set of linear equations, physical quantities such as 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. The nanomotor distribution, reservoir fluid pressure and flow rate predicted by the model are compared with the actual measured values. If there is a deviation, the cause of the deviation is analyzed, and the model assumptions, parameter values, etc. are checked to see if they are reasonable. The model is adjusted and optimized until the model prediction results are consistent with the actual situation.

[0069] The present invention can describe in detail the flow law of the fluid in the reservoir and the movement characteristics of the nanomotor therein by respectively constructing a reservoir fluid flow model and a nanomotor motion model, and then couple the two to obtain a reservoir-nanomotor coupling model, which can simulate the movement of the nanomotor in the reservoir under different geological parameters and nanomotor characteristic parameters, and provide a theoretical basis for the subsequent determination of the initial injection speed and initial injection pressure of the nanomotor.

[0070] Specifically, the step S2 includes:

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

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

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

[0074] In a specific embodiment, the movement of the nanomotor during the initial injection process is simulated based on the reservoir-nanomotor coupling model, and the position at the moment when the movement state of the nanomotor changes significantly is extracted as a movement node. Each movement node contains the position coordinates of the nanomotor and the movement state at that moment. The movement nodes are screened based on specific areas in the reservoir (crude oil-rich areas, low permeability areas, etc.), locations where the movement state changes significantly, and specific time points (the moment when the nanomotor begins to work, the moment when the maximum oil recovery effect is achieved, etc.). The key movement nodes can be determined by calculating the relevant parameters of each movement node (such as the distance between the position and the target area, the speed change rate, etc.) and comparing them with the screening criteria. For example, if the screening criterion is that the node within a certain range from the crude oil-rich area to which the nanomotor reaches is the key movement node, then the distance between each movement node and the crude oil-rich area is calculated, and the nodes whose distance meets the conditions are marked as key movement nodes. It is understandable that the selected key motion nodes are analyzed to determine the conditions that the nanomotor needs to meet to reach these nodes. For example, the speed and position requirements of the nanomotor at the key motion nodes, as well as the reservoir resistance that needs to be overcome during the movement, are analyzed. If the key motion node is located in the low permeability area of ​​the reservoir, then the nanomotor needs to have sufficient power to reach the area, which places higher requirements on the initial injection speed and initial injection pressure. Based on the requirements of the key motion nodes, an objective function is established to determine the constraints that the initial injection speed and initial injection pressure need to meet. The objective function is solved using an optimization algorithm (such as a genetic algorithm, a particle swarm algorithm, etc.). Under the premise of meeting the constraints, 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 motion trajectory of the nanomotor in the reservoir is calculated, and the advantages and disadvantages of each parameter combination are evaluated according to the objective function, and finally the optimal initial injection speed and initial injection pressure are obtained.

[0075] The present invention can determine several motion nodes of the nanomotor based on the reservoir-nanomotor coupling model, and these nodes reflect the states of the nanomotor at different positions in the reservoir. By further screening out key motion nodes, the positions of the nanomotor with important significance in the reservoir can be clarified, and a clearer understanding of the motion path of the nanomotor in the reservoir can be obtained. The initial injection speed and the initial injection pressure are determined based on the key motion nodes, which can ensure that the nanomotor moves along the expected path, thereby optimizing the overall motion planning of the nanomotor in the reservoir, improving the effectiveness of its distribution in the reservoir, and improving the injection efficiency of the nanomotor.

[0076] Step S3, injecting the nanomotor into the target reservoir area based on the initial injection speed and the initial injection pressure, and detecting the initial behavior characteristics of the nanomotor during the initial injection process, including movement 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 that can detect the behavioral characteristics of nanomotors during injection into a target reservoir area falls within the scope of protection of the present invention and will not be described in detail herein.

[0078] Step S4, determining an injection method of a key injection process based on the initial behavior characteristics of the nanomotor within a preset time period, including a continuous injection method and an interval injection method;

[0079] Wherein, the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode is determined based on the distribution range and the gathering area;

[0080] and, determining the interval injection pressure and / or interval injection speed and interval time corresponding to the interval injection method based on the moving speed and the distribution range;

[0081] See also 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, determining the injection method of the key injection process includes:

[0082] Step S41, determining a motion characteristic value based on the motion trajectory of the nanomotor within a preset time period;

[0083] Step S42, determining a movement characteristic value based on the movement speed of the nanomotor within a preset time period;

[0084] Step S43: determining an injection method of a key injection process based on the motion characteristic value and the movement characteristic value.

[0085] Specifically, the step S43 includes:

[0086] The motion characteristic value is compared with a preset motion characteristic value, and the movement characteristic value is compared with a preset movement characteristic value, and an injection method of a key injection process is determined based on the comparison result.

[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 in which the distance between the end point of the trajectory and the trajectory fork is greater than a set distance is determined as a branch trajectory) or the frequency of obvious changes in the motion direction (the angle between the velocity vectors of adjacent trajectory points is greater than a set angle), and the movement characteristic value is determined based on the standard deviation of the movement speed of the nanomotor within the 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 mobile characteristic value is less than the preset mobile characteristic value, it indicates that the nanomotor can move relatively smoothly in the reservoir, and a continuous injection method can be used 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 mobile characteristic value is greater than or equal to the preset mobile characteristic value, it indicates that the movement of the nanomotor in the reservoir is subject to much interference and the movement is unstable. An interval injection method can be used 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 trajectory of the nanomotor that has passed the qualification test in the historical data. Preferably, the set distance value range is set to 0.5m~1.0m, the set angle value range is set to 30°~50°, the preset motion characteristic value range is set to 5~8, the preset movement characteristic value range is set to 1~3, and the preset time period value range is set to 30min~50min.

[0090] The motion trajectory of the present invention can show the spatial movement path of the nanomotor in the oil reservoir, and the motion characteristic value determined therefrom can reflect its motion information. The movement speed directly reflects the changing law of the speed of the nanomotor in the oil reservoir fluid. The comprehensive motion characteristic value and movement characteristic value can fully understand the behavior of the nanomotor in the oil reservoir, provide an accurate basis for determining the injection method, thereby improving the injection efficiency and distribution uniformity of the nanomotor.

[0091] See also Figure 3 As shown, it is a logical judgment diagram for determining whether to adjust the injection pressure and injection speed corresponding to the continuous injection mode in an embodiment of the present invention; specifically, in the step S4, the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode is determined based on the distribution range and the gathering area, including:

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

[0093] Step S45, determining the injection pressure and injection speed corresponding to the continuous injection method based on the volume of the key gathering area and the distribution range.

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

[0095] If the ratio of the volume of the key gathering area to the total volume of the distribution range is greater than a first preset ratio, adjusting the injection pressure corresponding to the continuous injection mode to obtain a continuous injection pressure;

[0096] If the ratio of the volume of the key gathering area to the total volume of the distribution range is less than a second preset ratio, adjusting the injection speed corresponding to the continuous injection mode to obtain a continuous injection speed;

[0097] If the ratio of the volume of the key gathering 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;

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

[0099] In a specific embodiment, the distribution range is the maximum area enclosed by the motion trajectory of the nanomotor, and the aggregation area is the area where the number of nanomotor per unit volume is greater than a first preset number. The volume of each aggregation area and its volume share within the nanomotor distribution range are calculated, and the aggregation area with the largest share is determined as the key aggregation area.

[0100] It can be understood that if the ratio of the volume of the key aggregation area to the total volume of the distribution range is greater than the first preset ratio, it indicates that the volume of the key aggregation area is relatively large. In order to avoid blockage caused by excessive aggregation of nanomotors in local areas, and enable the nanomotors to overcome the resistance brought by narrow pores and tortuous channels, and smoothly travel through the pores of the reservoir, thereby expanding their migration range in the reservoir, the injection pressure corresponding to the continuous injection method should be increased, and the continuous pressure adjustment amount should be determined based on the product of the ratio of the volume of the key aggregation area to the total volume of the distribution range and the initial injection pressure. 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 area to the total volume of the distribution range is less than the second preset ratio, it indicates that the aggregation area is relatively dispersed. In order to enable the nanomotors to be evenly distributed in the target reservoir area, the injection speed needs to be appropriately increased. The continuous speed adjustment amount is determined based on the product of the ratio of the volume of the key aggregation area to the total volume of the distribution range and the initial injection speed. The continuous injection speed is the sum of the initial injection speed and the continuous speed adjustment amount.

[0102] It can be understood that if the ratio of the volume of the key gathering 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 method will not be adjusted, and the initial injection pressure and initial injection speed will continue to be used for continuous injection.

[0103] In implementation, actual implementers can set the first preset ratio and the second preset ratio according to actual conditions or based on the aggregation area and distribution range of nanomotors that have passed the qualification test during the initial injection process in historical data. Preferably, the first preset ratio is set in the range of 0.01 to 0.1, and the second preset ratio is set in the range of 0.003 to 0.005.

[0104] The present invention determines the key aggregation area of ​​nanomotors based on the distribution range and aggregation area of ​​nanomotors 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 method according to the distribution range of nanomotors and the key aggregation area, which can optimize the overall distribution of nanomotors in the oil reservoir and improve the injection efficiency of nanomotors.

[0105] See also Figure 4 As shown, it is a logical judgment diagram for determining whether to adjust the injection pressure and injection speed corresponding to the interval injection method in an embodiment of the present invention; specifically, in the step S4, the interval injection pressure and / or interval injection speed corresponding to the interval injection method is determined based on the moving speed and the distribution range, including:

[0106] Step S46, determining a first comparison value based on a change in the moving speed of the nanomotor within a preset time period;

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

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

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

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

[0111] If the second comparison value is less than the second preset comparison value, the injection pressure corresponding to the interval injection method is adjusted to obtain the interval injection pressure.

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

[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, and 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, and the injection efficiency of the nanomotor can be improved by increasing the injection speed corresponding to the interval injection method; the interval speed adjustment amount is determined according to the product of the first comparison value and the initial injection speed, and the interval injection speed is determined according to the product of the initial injection speed and the interval speed adjustment amount.

[0114] It is understandable that if the second comparison value is less than the second preset comparison value, it indicates that the distribution range of the nanomotor is significantly different from the standard distribution range, and the injection pressure corresponding to the interval injection method can be increased to narrow the gap with the standard distribution range and improve the distribution uniformity of the nanomotor. The interval pressure adjustment amount is determined according to the product of the second comparison value and the initial injection pressure, and the interval injection pressure is determined according to the product of the initial injection pressure and the interval 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 interval injection method will not be adjusted, and the initial injection pressure and initial injection speed will continue to be used for interval injection.

[0116] In implementation, 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 the moving speed and distribution range of the nanomotor that has passed the qualification test in the initial injection process in the historical data, or simulate and set the first preset comparison value, the second preset comparison value and the standard distribution range based on the reservoir-nanomotor coupling model. Preferably, the first preset comparison value range is set to 0.5-0.7, the second preset comparison value range is set to 0.2-0.4, and the standard distribution range range is set to 0.1m 3 ~0.3m 3 .

[0117] It is understandable that the interval 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.

[0118] The change in movement speed and distribution range of the nanomotor of the present invention are important indicators reflecting its movement state and effect in the oil reservoir. The injection pressure and speed under the interval injection method are determined by these two indicators, which can make the injection process more in line with the actual situation of the nanomotor in the oil reservoir, flexibly adapt to the dynamic changes inside the oil reservoir, and improve the distribution uniformity of the nanomotor.

[0119] Step S5, detecting key behavior characteristics of the nanomotor during a key injection process, and determining whether the injection method needs to be adjusted based on the key behavior characteristics.

[0120] Specifically, step S5 includes:

[0121] Whether the injection mode needs to be adjusted is determined based on the comparison result between the initial behavior feature and the key behavior feature.

[0122] In a specific embodiment, based on the initial behavior features Y1, Y2, ..., Y j , …, Y m With 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, m is the number of behavioral features, if the feature comparison value is greater than the preset feature comparison value, it is determined that the injection method does not need to be adjusted, if the feature comparison value is less than or equal to the preset feature comparison value, it is determined that the injection method needs to be adjusted, and the injection method is re-determined according to the detected key behavioral features.

[0123] In implementation, actual implementers can set preset feature comparison values ​​according to actual conditions or based on the comparison results of initial behavior features that have passed qualification inspection with key behavior features in historical data. Preferably, the preset feature comparison value range is set to 0.7 to 0.9.

[0124] The initial behavior characteristics of the present invention reflect the performance of the nanomotor at the initial stage of injection, while the key behavior characteristics reflect its status in the subsequent key stages. By comparing the two, the behavioral changes of the nanomotor can be discovered in time to determine whether the injection method needs to be adjusted. This can improve the accuracy and real-time nature of the judgment, thereby improving 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, so that the initial injection process of the nanomotor is adapted to the geological conditions and self-characteristics of the reservoir, which is conducive to its effective movement in the reservoir pores and improves the injection efficiency of the nanomotor. By detecting the initial behavior characteristics of the nanomotor during the initial injection process, determining the injection method of the key injection process, and realizing accurate control of the nanomotor oil displacement process, the distribution and movement of the nanomotor in the reservoir can be made more in line with the reservoir exploitation requirements, avoiding excessive aggregation of the nanomotor at the injection end, and improving the distribution uniformity of the nanomotor. In the key injection process, the key behavior characteristics of the nanomotor are continuously detected, and it is determined whether the injection method needs to be adjusted accordingly, 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, and always maintain the best working state of the nanomotor in the reservoir, further improving the exploitation efficiency and recovery rate.

[0126] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying 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. A method for oil extraction using nanomotors, characterized in that: include: Step S1, obtaining geological parameters of the target reservoir area and 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; Step S2, constructing a reservoir-nanomotor coupling model based on the geological parameters and the characteristic parameters, and determining an initial injection velocity and an initial injection pressure of the nanomotor; Step S3, injecting the nanomotor into the target reservoir area based on the initial injection speed and the initial injection pressure, and detecting the initial behavior characteristics of the nanomotor during the initial injection process, including movement speed, movement trajectory, distribution range and aggregation area; Step S4, determining an injection method of a key injection process based on the initial behavior characteristics of the nanomotor within a preset time period; Wherein, the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode is determined based on the distribution range and the gathering area; and, determining the interval injection pressure and / or interval injection speed and interval time corresponding to the interval injection method based on the moving speed and the distribution range; Step S5, detecting key behavior characteristics of the nanomotor during a key injection process, and determining whether the injection method needs to be adjusted based on the key behavior characteristics.

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

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

4. The oil extraction method using nano motors according to claim 3, characterized in that: In step S4, the injection method of the key injection process is determined, including: Step S41, determining a motion characteristic value based on the motion trajectory of the nanomotor within a preset time period; Step S42, determining a movement characteristic value based on the movement speed of the nanomotor within a preset time period; Step S43: determining an injection method of a key injection process based on the motion characteristic value and the movement characteristic value.

5. The oil extraction method using nano motors according to claim 4, characterized in that: In the step S43, it includes: The motion characteristic value is compared with a preset motion characteristic value, and the movement characteristic value is compared with a preset movement characteristic value, and an injection method of a key injection process is determined based on the comparison result.

6. The oil extraction method using nano motors according to claim 5, characterized in that: In the step S4, the continuous injection pressure / continuous injection speed corresponding to the continuous injection mode is determined based on the distribution range and the gathering area, including: Step S44, determining a key aggregation area of ​​the nanomotor based on the distribution range and aggregation area of ​​the nanomotor within a preset time period; Step S45, determining the injection pressure and injection speed corresponding to the continuous injection method based on the volume of the key gathering area and the distribution range.

7. The oil extraction method using nano motors according to claim 6, characterized in that: In the step S45, it includes: If the ratio of the volume of the key gathering area to the total volume of the distribution range is greater than a first preset ratio, adjusting the injection pressure corresponding to the continuous injection mode to obtain a continuous injection pressure; If the ratio of the volume of the key gathering area to the total volume of the distribution range is less than a second preset ratio, adjusting the injection speed corresponding to the continuous injection mode to obtain a continuous injection speed; Among them, the first preset ratio is greater than the second preset ratio.

8. The oil extraction method using nano motors according to claim 7, characterized in that: In the step S4, determining the interval injection pressure and / or interval injection speed corresponding to the interval injection method based on the moving speed and the distribution range includes: Step S46, determining a first comparison value based on a change in the moving speed of the nanomotor within a preset time period; Step S47, determining a second comparison value based on the distribution range of the nanomotor within a preset time period; Step S48, determining the injection pressure and injection speed corresponding to the interval injection method based on the first comparison value and the second comparison value.

9. The oil extraction method using nano motors according to claim 8, characterized in that: In the step S48, it includes: If the first comparison value is greater than the first preset comparison value, adjusting the injection speed corresponding to the interval injection mode to obtain the interval injection speed; If the second comparison value is less than the second preset comparison value, the injection pressure corresponding to the interval injection method is adjusted to obtain the interval injection pressure.

10. The oil extraction method using nano motors according to claim 9, characterized in that: In the step S5, it includes: Whether the injection mode needs to be adjusted is determined based on the comparison result between the initial behavior feature and the key behavior feature.

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