Heterogeneous oil reservoir polymer flooding mining method and device and computer equipment

Abstract

The embodiment of the invention provides a heterogeneous oil reservoir polymer flooding exploitation method and device and computer equipment, and the method comprises the steps that a target heterogeneous oil reservoir is divided into a plurality of displacement units according to oil displacement efficiency; determining a polymer displacement system of each displacement unit, wherein the molecular weight ranges and / or concentration ranges and / or volume ranges of the displacement systems of the displacement units are different; determining a displacement sequence of the plurality of displacement units; sequentially injecting the displacement systems of the displacement units according to the displacement sequence, and determining the injection time of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence so as to exploit the displacement units. According to the method, the displacement systems with different molecular weights are injected into different levels of pore throats of all the displacement units in an echelon mode with different injection concentrations, injection volumes and injection pressures, graded utilization and effective displacement of all the displacement units with remaining oil of micro pores with different scales are achieved, and the recovery efficiency of an oil reservoir is improved.

Description

Technical Field

[0001] The present specification relates to the technical field of oilfield development, and in particular to a method, device and computer equipment for polymer flooding of heterogeneous oil reservoirs. Background Art

[0002] The reservoir of heterogeneous sandstone reservoirs is highly heterogeneous and has a complex pore structure. The remaining oil after water flooding is highly dispersed and exists at the centimeter level or lower. Microscopically, it exists in the form of clusters, islands, corners, oil films, and throat residual oil. Inefficient and ineffective water circulation is serious, and it is difficult to continue water flooding. The dynamic characteristics analysis of polymer flooding mining in the mine and the evaluation of the experimental effect show that the existing polymer injection method has the following defects:

[0003] (1) Due to the different water absorption index and injection capacity of polymer injection wells, the injection capacity of polymer injection wells varies greatly with the extension of injection time. The injection capacity of some wells has seriously declined. Before reaching the injection volume designed by the injection-production plan, nearly 1 / 3 of the wells cannot be injected, resulting in aggravated injection-production imbalance in the polymer injection area, which seriously affects the injection-production effect.

[0004] (2) After long-term water injection and flushing, large or even extra-large pores have been formed in some formations. The low-concentration injection plug has a poor blocking effect on the large pores and cannot play the role of proper flow control and profile adjustment. The polymer flows along the large pores more seriously, causing an invalid circulation of the polymer in the formation, affecting the polymer flooding effect.

[0005] (3) When the injection and polymerizing area was initially developed from water injection to injection and polymerizing, due to the serious heterogeneity of the formation plane, the production conditions inside and on the plane of the target layer in the injection and polymerizing area were quite different. When the original injection method was implemented, the large pores in some well areas could not be effectively blocked, and the injection capacity of other injection and polymerizing wells in the same layer was seriously insufficient. The contradiction between the layer and the plane could not be alleviated, and the oil injection and production capacity of the low permeability strip was still low, resulting in poor production effects inside and on the plane, and failing to achieve the expected oil recovery effect.

[0006] In summary, the existing polymer flooding injection production method of directly injecting large amounts of polymer has the problem of easily causing the polymer agent to advance along the high permeability unit, making it difficult to mobilize the medium and low permeability units, with limited affected volume and low oil recovery efficiency. Summary of the invention

[0007] In view of the above-mentioned problems of the prior art, the purpose of the embodiments of this specification is to provide a method, device and computer equipment for polymer flooding of heterogeneous oil reservoirs to solve the problems existing in the existing polymer injection method that the polymer agent easily advances along the high permeability unit, the medium and low permeability units are difficult to mobilize, the affected volume is limited, and the oil recovery efficiency is low.

[0008] In order to solve the above technical problems, the specific technical solutions of the embodiments of this specification are as follows:

[0009] In a first aspect, the embodiments of this specification provide a method for polymer flooding production in a heterogeneous reservoir, comprising:

[0010] According to the oil displacement efficiency, the target heterogeneous reservoir is divided into multiple displacement units;

[0011] Determining a polymer displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure;

[0012] determining a displacement order of the plurality of displacement units;

[0013] The displacement systems of the displacement units are injected sequentially according to the displacement sequence, and the injection timing of the displacement system of the subsequent displacement unit is determined according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to produce each displacement unit.

[0014] In a specific embodiment, the target heterogeneous reservoir is divided into a plurality of displacement units according to the oil displacement efficiency, including:

[0015] dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and greater than or equal to a second oil recovery efficiency threshold as a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold;

[0016] The area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold is divided into a second displacement unit.

[0017] In a preferred embodiment, the displacement system of each displacement unit is determined, and the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure, including:

[0018] Determining the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit;

[0019] Calculate the injection concentration of each displacement system according to the viscosity of crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit;

[0020] According to the injection concentration of each displacement system and the relationship curve between injection concentration and injection volume, the injection volume of each displacement system is calculated;

[0021] The injection pressure of each displacement system is determined according to the molecular weight, injection concentration and injection volume of each displacement system.

[0022] In a preferred embodiment, the injection concentration of each displacement system is calculated based on the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit, further comprising:

[0023] Calculating the surface viscosity of the displacement system according to the crude oil viscosity of the target heterogeneous oil reservoir;

[0024] The injection concentration of each displacement system is calculated based on the surface viscosity of the displacement system and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system.

[0025] In a preferred embodiment, the surface viscosity of the displacement system is calculated as follows:

[0026]

[0027] Among them, μ 地面 is the surface viscosity of the displacement system, μ 地下 is the underground viscosity of the displacement system; A is the formation shear viscosity loss; B is the shear viscosity loss of the surface pipe network system;

[0028] μ 地下 =Cμ 原油 ;

[0029] Among them, μ 原油 is the crude oil viscosity of the heterogeneous oil reservoir, and C is a constant coefficient greater than 0.

[0030] In a preferred embodiment, the area in the target heterogeneous oil reservoir with an oil recovery efficiency less than a second oil recovery efficiency threshold is divided into a second displacement unit, further comprising:

[0031] dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a second oil recovery efficiency threshold and greater than or equal to a third oil recovery efficiency threshold as a second displacement unit, wherein the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold;

[0032] dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and greater than or equal to a fourth oil recovery efficiency threshold as a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; and

[0033] A region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold is divided into a fourth displacement unit, and the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold.

[0034] In a preferred embodiment, the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system is obtained by the following method:

[0035] A plurality of core samples are obtained from a plurality of different displacement units of a plurality of heterogeneous oil reservoirs with different crude oil viscosities, and the oil displacement efficiencies of the different displacement units are different;

[0036] The displacement system was used to perform polymer flooding on each core sample with different molecular weights and different injection concentrations;

[0037] Obtain the change value of the remaining oil saturation of each core sample before and after the completion of polymer flooding;

[0038] Determining the molecular weight of the displacement system that matches the oil displacement efficiency of each displacement unit according to the residual oil saturation change value;

[0039] Determining the injection concentration of the displacement system adapted to each displacement unit according to the molecular weight of the displacement system adapted to the oil displacement efficiency of each displacement unit and the residual oil saturation change value;

[0040] According to the injection concentration of the displacement system matched with each displacement unit and the crude oil viscosity of the heterogeneous oil reservoir corresponding to each displacement unit, a viscosity-concentration relationship curve corresponding to the molecular weight of the displacement system of each displacement unit is fitted.

[0041] In a preferred embodiment, the injection concentration of each displacement system is calculated based on the surface viscosity of the displacement system and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit, further comprising:

[0042] The injection concentration of the first displacement unit is calculated according to the following viscosity-concentration relationship curve:

[0043] μ 地面 =3×10 -16 x1 5 -5×10 -12 x1 4 +2×10 -8 x1 3 -0.0005x1 2 +0.41x1-50.676;

[0044] The injection concentration of the second displacement unit is calculated according to the following viscosity-concentration relationship curve:

[0045] μ 地面 =2×10 -16 x2 5 -3×10 -12 x2 4 +1×10 -8 x2 3 -0.0002x2 2 +0.1076x2+30.78;

[0046] The injection concentration of the third displacement unit is calculated according to the following viscosity-concentration relationship curve:

[0047] μ 地面 =2×10 -16 x3 5 -1×10 -12 x3 4 +8×10 -10 x3 3 +0.0002x3 2 -0.2287x3+116.84;

[0048] The injection concentration of the fourth displacement unit is calculated according to the following viscosity-concentration relationship curve:

[0049] μ 地面 =-5×10 -16 x4 5 +7×10 -12 x4 4 -4×10 -8 x4 3 +0.001x4 2 -0.7676x4+214.78;

[0050] Among them, μ 地面 is the surface viscosity of the displacement system, and x1, x2, x3 and x4 are the injection concentrations of the displacement systems of the first displacement unit, the second displacement unit, the third displacement unit and the fourth displacement unit, respectively.

[0051] In a preferred embodiment, the relationship curve between injection concentration and injection volume is:

[0052] x i =kv i +b;

[0053] Among them, x i is the injection concentration of the displacement system of the ith displacement unit, in mg / L; v i is the injection volume of the displacement system of the ith displacement unit, in PV; k is the fitting slope, and b is the fitting intercept.

[0054] In a preferred embodiment, before the displacement systems of the displacement units are sequentially injected according to the displacement sequence, the method further comprises:

[0055] dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is greater than or equal to a first oil recovery efficiency threshold as a plugging layer;

[0056] The blocking layer is blocked or protected from radiation.

[0057] In a preferred embodiment, determining the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence further includes:

[0058] Calculating the displacement pressure change rate according to the displacement pressure change curve;

[0059] When the pressure change rate is less than a preset pressure change rate threshold, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

[0060] In a preferred embodiment, determining the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence further includes:

[0061] Calculating the displacement pressure change rate according to the displacement pressure change curve;

[0062] When the pressure change rate is less than a preset pressure change rate threshold and is maintained for a preset time, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

[0063] In a preferred embodiment, the oil displacement efficiency is calculated by the following formula:

[0064]

[0065] Where ED is the oil recovery efficiency; S or is the residual oil saturation of the target heterogeneous reservoir after water flooding; S o is the oil saturation of the target heterogeneous oil reservoir before water flooding.

[0066] In a second aspect, the embodiments of this specification provide a heterogeneous reservoir polymer flooding production device, comprising:

[0067] A partitioning module is used to divide the target heterogeneous reservoir into a plurality of displacement units according to the oil displacement efficiency;

[0068] A first determination module is used to determine the polymer displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure;

[0069] A second determination module, used to determine a displacement order of the plurality of displacement units;

[0070] The displacement module is used to sequentially inject the displacement systems of each displacement unit according to the displacement sequence, and determine the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to mine each displacement unit.

[0071] Furthermore, the division module includes:

[0072] A first division unit is used to divide a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and is greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold;

[0073] The second division unit is used to divide the area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than a second oil recovery efficiency threshold into a second displacement unit.

[0074] In some preferred embodiments, the partitioning module includes:

[0075] A first division unit is used to divide a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and is greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold;

[0076] A second division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a second oil recovery efficiency threshold and is greater than or equal to a third oil recovery efficiency threshold into a second displacement unit, wherein the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold;

[0077] A third division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and is greater than or equal to a fourth oil recovery efficiency threshold into a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; and

[0078] The fourth division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold into a fourth displacement unit, and the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold.

[0079] In some preferred embodiments, the first determining module further includes:

[0080] A molecular weight determination unit, used to determine the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit;

[0081] An injection concentration determination unit, used to calculate the injection concentration of each displacement system according to the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit;

[0082] An injection volume determination unit, used to calculate the injection volume of each displacement system according to the injection concentration of each displacement system and the injection concentration-injection volume relationship curve;

[0083] The injection pressure determination unit is used to determine the injection pressure of each displacement system according to the molecular weight, injection concentration and injection volume of each displacement system.

[0084] In a third aspect, an embodiment of the present specification provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided by the above technical solution when executing the computer program.

[0085] In a fourth aspect, an embodiment of the present specification further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method provided by the above technical solution is implemented.

[0086] In a fifth aspect, the embodiments of this specification also provide a computer program product, comprising at least one instruction or at least one program, wherein the at least one instruction or the at least one program is loaded and executed by a processor to implement the method provided by the above technical solution.

[0087] By adopting the above-mentioned technical scheme, a polymer flooding production method, device and computer equipment for heterogeneous oil reservoirs provided in the embodiments of this specification utilize oil recovery efficiency to divide the target heterogeneous oil layer, and match each displacement unit obtained by the division with a displacement system that is compatible with it, and adopt a graded and cascaded production working mode, thereby improving the accuracy and convenience of the division of each displacement unit; and allowing the displacement systems with different molecular weights to be injected into different levels of pore throats of each displacement unit at different injection concentrations, injection volumes and injection pressures, thereby realizing the graded mobilization and effective displacement of each displacement unit with residual oil in microscopic pores of different scales, which is conducive to the effective adjustment of interlayer heterogeneity.

[0088] In order to make the above and other purposes, features and advantages of the embodiments of this specification more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0090] Figure 1 A schematic diagram showing the steps of a polymer flooding production method for a heterogeneous oil reservoir provided in an embodiment of this specification is shown;

[0091] Figure 2A schematic diagram showing the steps of determining the polymer displacement system of each displacement unit in the embodiment of this specification is shown;

[0092] Figure 3 A schematic diagram showing the steps for calculating the injection concentration of each displacement system in the embodiments of this specification is shown;

[0093] Figure 4 The viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system;

[0094] Figure 5 It is the relationship curve between injection concentration and injection volume of the displacement system;

[0095] Figure 6 A schematic diagram showing the steps of determining the injection timing of the displacement system of the displacement unit located after the current displacement unit in the displacement sequence in the embodiment of this specification is shown;

[0096] Figure 7 A schematic diagram showing another step of determining the injection timing of the displacement system of the displacement unit located after the current displacement unit in the displacement sequence in the embodiment of this specification;

[0097] Figure 8 A schematic diagram of the structure of a heterogeneous oil reservoir polymer flooding production device provided in an embodiment of this specification is shown;

[0098] Fig. 9 A schematic diagram of the structure of the division modules in the embodiment of this specification is shown;

[0099] Fig.10 Another structural schematic diagram of the division module in the embodiment of this specification is shown;

[0100] Fig.11 A schematic diagram of the structure of the first determination module in the embodiment of this specification is shown;

[0101] Fig.12 The following is a schematic diagram showing the structure of a computer device provided in an embodiment of the present specification.

[0102] 81. Divide modules;

[0103] 811, first division unit;

[0104] 812, second division unit;

[0105] 813, the third division unit;

[0106] 814, the fourth division unit;

[0107] 82. A first determination module;

[0108] 821. Molecular weight determination unit;

[0109] 822. Injection concentration determination unit;

[0110] 823. Injection volume determination unit;

[0111] 824. Injection pressure determination unit;

[0112] 83. A second determination module;

[0113] 84. Displacement module;

[0114] 1202. Computer equipment;

[0115] 1204, processor;

[0116] 1206. Memory;

[0117] 1208, driving mechanism;

[0118] 1210, input / output module;

[0119] 1212. Input device;

[0120] 1214. Output device;

[0121] 1216. Presentation equipment;

[0122] 1218. Graphical user interface;

[0123] 1220, network interface;

[0124] 1222, communication link;

[0125] 1224. Communication bus. DETAILED DESCRIPTION

[0126] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0127] It should be noted that the terms "first", "second", etc. in this specification and claims and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0128] In order to solve the above problems, the embodiments of this specification provide a method and device for polymer flooding of heterogeneous oil reservoirs, which can solve the problems of the existing polymer injection method that the polymer agent is easy to advance along the high permeability unit, the residual oil in the medium and low permeability units is difficult to mobilize, and the affected volume is limited and the oil recovery efficiency is low. Figure 1 This is a schematic diagram of the steps of a polymer flooding method for heterogeneous oil reservoirs provided in the embodiments of this specification. This specification provides the method operation steps described in the embodiments or flow charts, but more or fewer operation steps may be included based on conventional or non-creative work. The order of steps listed in the embodiments is only one way of executing the steps among many orders, and does not represent the only order of execution. When the actual system or device product is executed, it can be executed in the order of the methods shown in the embodiments or drawings or in parallel. Specifically, Figure 1 As shown, the method may include:

[0129] S110: Divide the target heterogeneous oil reservoir into a plurality of displacement units according to the oil displacement efficiency.

[0130] The oil displacement efficiency can be calculated by the following formula:

[0131]

[0132] Where ED is the oil recovery efficiency; S or is the residual oil saturation of the target heterogeneous reservoir after water flooding; S o is the oil saturation of the target heterogeneous oil reservoir before water flooding.

[0133] It should be noted that after water flooding the oil reservoir, the same reservoir of the oil reservoir may contain one displacement unit or multiple different displacement units. In the embodiment of this specification, the target non-average oil reservoir is divided into multiple displacement units according to the oil recovery efficiency, which is conducive to reducing the difficulty of the division operation while ensuring that the division of each displacement unit has a high accuracy, and is simple and convenient. In some other possible embodiments, the target non-average oil reservoir can also be divided by comprehensively considering parameters such as water production rate, water saturation, and permeability.

[0134] S120: Determine a displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure.

[0135] In the embodiments of this specification, different displacement systems are used for different displacement units, so that the displacement system corresponding to each displacement unit can be effectively injected into the pore throat structure of the displacement unit, avoiding the problem of polymer crossflow or ineffective injection, which is beneficial to increasing the ratio of formation absorption thickness, improving the uniformity of the profile, and facilitating subsequent mining operations.

[0136] It should be noted that, in this specification, the displacement system corresponding to each displacement unit may be a single polymer, or a mixture of multiple polymers having the same molecular weight range and / or the same concentration range and / or the same volume range.

[0137] S130: Determine a displacement order of the plurality of displacement units.

[0138] In the embodiments of this specification, each displacement unit is displaced in the order of oil displacement efficiency from high to low.

[0139] S140: injecting the displacement systems of the displacement units in sequence according to the displacement sequence, and determining the injection timing of the displacement system of the subsequent displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to exploit each displacement unit.

[0140] That is, according to the displacement sequence, the displacement unit with the highest oil displacement efficiency is first displaced and the displacement pressure change curve of the displacement unit with the highest oil displacement efficiency during the displacement process is obtained. According to the displacement pressure change curve, it is judged whether it is time to displace the displacement unit in the next layer (i.e., the displacement unit with the second highest oil displacement efficiency), that is, whether the displacement of the displacement unit with the highest oil displacement efficiency is completed. Furthermore, in the process of displacing the displacement unit with the second highest oil displacement efficiency, its displacement pressure change curve is obtained and used to judge whether it is time to displace the displacement unit in the next layer. Repeat the above steps until all the displacement units obtained by division are completed in a cascade displacement. In other words, except for the displacement unit at the first position in the displacement sequence, which starts displacement automatically, the time for other displacement units to start displacement is determined by the displacement pressure change curve of the displacement unit in the previous layer in the displacement sequence.

[0141] In the embodiments of the present specification, whether the timing for the next displacement unit to start displacement is reached is judged based on the displacement pressure change curve of the previous displacement unit in the displacement sequence, which can more accurately determine the timing for switching the displacement system of each displacement unit, thereby ensuring that each displacement unit can be displaced using a displacement system that is compatible with its oil recovery efficiency, pore throat structure and other characteristics, thereby ensuring the effectiveness of the displacement system.

[0142] The embodiment of this specification provides a method for polymer flooding of heterogeneous reservoirs, which uses oil displacement efficiency to divide the target heterogeneous oil layer, and matches each displacement unit obtained by the division with a displacement system that is compatible with it, and adopts a graded and cascaded mining working mode, so that when the production pressure difference is constant, the displacement system with different molecular weights is injected into different levels of pore throats of each displacement unit at different injection concentrations, injection volumes and injection pressures, thereby realizing the graded use and effective displacement of each displacement unit with residual oil in microscopic pores of different scales, which is conducive to the effective adjustment of interlayer heterogeneity and the maximization of the use of polymer flooding reserves in heterogeneous sandstone reservoirs, thereby improving the recovery rate of the reservoir. And through intelligent production management, automatic data collection and remote monitoring, process automatic control and timely information feedback are realized, and finally the purpose of economical and efficient polymer injection development is achieved.

[0143] Furthermore, in the embodiment of this specification, step S110: dividing the target heterogeneous reservoir into a plurality of displacement units according to the oil recovery efficiency range distribution may further include:

[0144] An area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and greater than or equal to a second oil recovery efficiency threshold is divided into a first displacement unit, and the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold; exemplarily, the first oil recovery efficiency threshold can be set to 45%, and the second oil recovery efficiency threshold can be set to 35%.

[0145] The area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold is divided into a second displacement unit.

[0146] If the displacement system corresponding to the first displacement unit is used to displace and exploit the entire target heterogeneous oil reservoir, the displacement system of the first displacement unit will find it difficult to enter the pore throat structure of the second displacement unit, resulting in poor displacement ability for the remaining oil in the second displacement unit; if the displacement system corresponding to the second displacement unit is used to displace and exploit the entire target heterogeneous oil reservoir, the displacement system of the second displacement unit will easily flow in the pore throat structure of the first displacement unit; neither can achieve a good displacement effect. In this application and this specification, the target heterogeneous oil reservoir is divided into at least two displacement units, and after the division is completed, the displacement systems corresponding to each of the two displacement units are used to carry out tiered exploitation of the target heterogeneous oil reservoir, and the remaining oil in different displacement units is mobilized in stages to improve the effectiveness and economy of the displacement system, and ultimately achieve the purpose of efficient injection and polymer development.

[0147] In a preferred embodiment, dividing the area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold into a second displacement unit may further include:

[0148] The area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than the second oil recovery efficiency threshold and greater than or equal to the third oil recovery efficiency threshold is divided into a second displacement unit, and the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold; illustratively, the third oil recovery efficiency threshold can be set to 25%.

[0149] dividing the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and greater than or equal to a fourth oil recovery efficiency threshold as a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; the fourth oil recovery efficiency threshold may be set to 15%, and

[0150] An area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold is divided into a fourth displacement unit, the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold, and the fifth oil recovery efficiency threshold can be set to 5%.

[0151] That is, preferably, the target heterogeneous oil reservoir is divided into four displacement units, so that the control granularity of the displacement system of each displacement unit is finer, thereby improving the production effect when the displacement system corresponding to each displacement unit is used to displace the target heterogeneous oil reservoir.

[0152] It should be noted that the number of the displacement units obtained by division can be adjusted and set according to the actual needs of oil reservoir exploitation. The more the number of displacement units, the better the graded utilization effect when using the displacement system corresponding to each displacement unit to displace each displacement unit, but it will increase the complexity of the injection operation. Therefore, in the embodiments of this specification, taking into account the recovery rate and operational convenience, it is preferred that the target is divided into 4 displacement units as shown in Table 1.

[0153] like Figure 2 As shown, in the example of this specification, in step S120, determining the polymer displacement system of each displacement unit may include the following steps:

[0154] S210: Determine the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit.

[0155] In the examples of this specification, the molecular weight values ​​of displacement units with different oil recovery efficiencies are shown in Table 1.

[0156] Table 1

[0157] level Oil recovery efficiency Molecular weight (range) First displacement unit 35％-45％ 25-30 million Second displacement unit 25％-35％ 20-25 million The third displacement unit 15％-25％ 15-20 million Fourth displacement unit 5％-15％ 10-15 million

[0158] S220: Calculate the injection concentration of each displacement system according to the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit.

[0159] Generally speaking, the injection concentration of the displacement system is positively correlated with the viscosity of the displaced phase (in the embodiment of this specification, the displaced phase is the crude oil in the heterogeneous reservoir). The higher the viscosity of the crude oil in the heterogeneous reservoir, the higher the concentration of the displacement system required to displace the crude oil, in order to have the best mobility control effect and better sweep effect. In the embodiment of this specification, the injection concentration of the corresponding displacement system is calculated according to the molecular weight of the displacement system of each displacement unit.

[0160] S230: Calculate the injection volume of each displacement system according to the injection concentration of each displacement system and the injection concentration-injection volume relationship curve.

[0161] When the injection concentration of the displacement system increases, the viscosity also increases, which will cause the volume of the oil-displacing zone formed by polymer flooding to become smaller. In order to ensure the scope of influence, when the concentration of the displacement system injection increases, the injection volume of the displacement system should also increase accordingly. And as the injection volume of the displacement system increases, the degree of recovery and the residual resistance coefficient increase, and when the injection volume of the displacement system reaches a certain value, the recovery rate curve and the residual resistance curve trend tend to be flat, which is due to the excessive injection volume of the displacement system, which leads to a decrease in the utilization rate of some displacement systems. The excessive injection volume of the displacement system will increase costs and reduce economic benefits. Therefore, a reasonable displacement system injection volume will optimize the crude oil recovery rate. In the embodiment of this specification, according to the injection concentration of the displacement system of each displacement unit, the corresponding injection volume of the displacement system is calculated, which is conducive to improving the displacement effect and improving the recovery rate.

[0162] S240: Determine the injection pressure of each displacement system according to the molecular weight, injection concentration and injection volume of each displacement system.

[0163] The larger the molecular weight and injection concentration of the displacement system, the higher the required injection pressure.

[0164] In the embodiments of this specification, the molecular weight of the displacement system applicable to each displacement unit is determined based on the oil recovery efficiency of each displacement unit obtained by division, and then the injection concentration, injection volume and injection pressure of the displacement system are calculated based on the molecular weight of the displacement system. In this way, the displacement system of each displacement unit is suitable for its oil recovery efficiency, pore throat structure and other characteristics, which is conducive to ensuring the effectiveness of the displacement system.

[0165] Furthermore, if Figure 3 As shown, in the embodiment of this specification, step S220: calculating the injection concentration of each displacement system according to the viscosity-concentration relationship curve corresponding to the crude oil viscosity of the target heterogeneous oil reservoir and the molecular weight of each displacement system of the displacement unit, may include:

[0166] S310: Calculate the surface viscosity of the displacement system according to the crude oil viscosity of the target heterogeneous oil reservoir.

[0167] The surface viscosity of the displacement system can be calculated according to the following formula:

[0168]

[0169] Among them, μ 地面 is the surface viscosity of the displacement system, μ 地下 is the underground viscosity of the displacement system; A is the formation shear viscosity loss; B is the shear viscosity loss of the surface pipe network system; the shear viscosity loss of the surface pipe network system may include the shear viscosity loss of the surface pump station pipeline, wellbore, and blasthole.

[0170] μ地下 =Cμ 原油 ;

[0171] Among them, μ 原油 is the crude oil viscosity of the heterogeneous oil reservoir, and C is a constant coefficient greater than 0.

[0172] Preferably, when the value of C is in the range of 2 to 5, the displacement system can have a better mobility control effect on the crude oil and a better sweep effect.

[0173] For example, in the examples of this specification, the viscosity of crude oil in the target heterogeneous reservoir is 14.3 mPa.s, the value of A can be 60%, and the value of B can be 40%, then the surface viscosity of the displacement system is calculated to be in the range of 119.2 mPa.s to 297.9 mPa.s.

[0174] S320: Calculate the injection concentration of each displacement system according to the surface viscosity of the displacement system and the viscosity-concentration relationship curve corresponding to the molecular weight of the displacement system of each displacement unit.

[0175] For example, in the examples of this specification, the molecular weights of the four displacement units obtained by dividing the target heterogeneous reservoir are determined to be 30 million, 25 million, 20 million and 15 million respectively. And the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system is as follows: Figure 4 As shown, they are:

[0176] The injection concentration of the first displacement unit is calculated according to the following viscosity-concentration relationship curve:

[0177]

[0178]

[0179]

[0180]

[0181] Among them, μ 地面 is the surface viscosity of the displacement system, x1, x2, x3 and x4 are the injection concentrations of the first displacement unit, the second displacement unit, the third displacement unit and the fourth displacement unit respectively; the injection concentrations x1, x2, x3 and x4 of each displacement system are calculated to be 2500-000mg / L, 2000-2500mg / L, 1500-2000mg / L and 1000-1500mg / L respectively.

[0182] Furthermore, in the examples of this specification, the relationship curve between the injection concentration and the injection volume of the displacement system is:

[0183] x i =kv i +b;

[0184] Among them, x i is the injection concentration of the displacement system of the ith displacement unit, in mg / L; v i is the injection volume of the displacement system of the ith displacement unit, in PV; k is the fitting slope, and b is the fitting intercept.

[0185] Preferably, the value of k is 25000, and the value of b is 0, that is, the relationship curve between the injection concentration and the injection volume is:

[0186] x i =25000v i ;

[0187] That is Figure 5 As shown, the injection volume of each displacement system can be calculated by substituting the calculated injection concentration of each displacement system into the relationship curve between injection concentration and injection volume.

[0188] It should be noted that the viscosity-concentration curves corresponding to the molecular weights of the above-mentioned displacement units and displacement systems, as well as the injection concentration and injection volume relationship curves, are adapted to the crude oil viscosity of the target heterogeneous reservoir as an example. Therefore, for different heterogeneous reservoirs, the specific expressions of the above-mentioned curves are different.

[0189] In the embodiments of this specification, the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system is obtained by simulation based on a large amount of experimental data. The specific method may include the following steps:

[0190] A plurality of core samples are obtained from a plurality of different displacement units of a plurality of heterogeneous oil reservoirs with different crude oil viscosities, and the oil displacement efficiencies of the different displacement units are different;

[0191] The displacement system was used to perform polymer flooding on each core sample with different molecular weights and different injection concentrations;

[0192] Obtain the change value of the remaining oil saturation of each core sample before and after the completion of polymer flooding;

[0193] Determining the molecular weight of the displacement system that matches the oil displacement efficiency of each displacement unit according to the residual oil saturation change value;

[0194] Determining the injection concentration of the displacement system adapted to each displacement unit according to the molecular weight of the displacement system adapted to the oil displacement efficiency of each displacement unit and the residual oil saturation change value;

[0195] According to the injection concentration of the displacement system matched with each displacement unit and the crude oil viscosity of the heterogeneous oil reservoir corresponding to each displacement unit, a viscosity-concentration relationship curve corresponding to the molecular weight of the displacement system of each displacement unit is fitted.

[0196] Furthermore, the injection concentration and injection volume relationship curve of the displacement system can be obtained by the following steps:

[0197] A plurality of core samples are obtained from a plurality of different displacement units of a plurality of heterogeneous oil reservoirs with different crude oil viscosities, and the oil displacement efficiencies of the different displacement units are different;

[0198] The displacement system was used to perform polymer displacement on each core sample with different molecular weights, different injection concentrations and different injection volumes;

[0199] Obtain the change value of the remaining oil saturation of each core sample before and after the completion of polymer flooding;

[0200] Determining the molecular weight of the displacement system that matches the oil displacement efficiency of each displacement unit according to the residual oil saturation change value;

[0201] Determining the injection concentration of the displacement system adapted to each displacement unit according to the molecular weight of the displacement system adapted to the oil displacement efficiency of each displacement unit and the residual oil saturation change value;

[0202] Determining the injection volume of the displacement system matched with each displacement unit according to the injection concentration of the displacement system matched with each displacement unit and the residual oil saturation;

[0203] According to the injection concentration and injection volume of the displacement system adapted to each displacement unit, a relationship curve between the injection concentration and the injection volume is obtained by fitting.

[0204] The molecular weight, injection concentration and injection volume of each displacement unit displacement system are summarized in Table 2:

[0205] Table 2

[0206] Displacement unit Oil recovery efficiency Molecular weight (range) concentration Volume range First displacement unit 35％-45％ 25-30 million 2500-3000mg / L 0.1-0.12 PV Second displacement unit 25％-35％ 20-25 million 2000-2500mg / L 0.08-0.1PV The third displacement unit 15％-25％ 15-20 million 1500-2000mg / L 0.06-0.08 PV Fourth displacement unit 5％-15％ 10-15 million 1000-1500mg / L 0.04-0.06PV

[0207] It should be noted that the molecular weight, injection concentration and injection volume of the displacement system of each displacement unit calculated and summarized in Table 2 above are adapted to the crude oil viscosity of the target heterogeneous reservoir as an example. Therefore, for different heterogeneous reservoirs, the molecular weight, injection concentration and injection volume of the displacement system are different from those in Table 2.

[0208] And, according to the molecular weight, injection concentration and injection volume of each displacement system, the injection pressure of each displacement system can be determined as:

[0209] The injection pressure is positively correlated with the injection concentration, and the injection pressure is positively correlated with the injection volume.

[0210] Specifically, for the first displacement unit, the maximum injection pressure can be set to 12MPa. For the first displacement unit, the displacement system has a high injection concentration and a high injection pressure, which can effectively block the large pores it has, thereby adjusting the injection profile, preventing the displacement system from breaking through the oil well and improving the residual oil utilization effect.

[0211] After the displacement operation of the first displacement unit is completed, the second displacement unit is displaced in stages. The injection pressure when displacing the second displacement unit should be lower than the injection pressure when displacing the first displacement unit. The injection concentration of the displacement system of the second displacement unit is adjusted according to the change of the injection pressure to make it lower than the injection concentration of the displacement system of the first displacement unit.

[0212] In the same way, the third displacement unit and the fourth displacement unit are displaced, and the injection pressure of the displacement system of each displacement unit is made smaller than the injection pressure of the displacement system of the displacement unit preceding the displacement unit in the displacement sequence.

[0213] As shown in Table 3, the polymer flooding method for heterogeneous reservoirs provided in the embodiments of this specification is to divide the target heterogeneous reservoir into multiple displacement units, and inject displacement systems with different molecular weights into each displacement unit in stages with different injection concentrations, injection volumes and injection pressures, so that the remaining oil in each displacement unit is effectively mobilized. As shown in Table 3, in the embodiments of this specification, the reduction value of the remaining oil saturation before and after polymer flooding shows the following rule: the third displacement unit> the second displacement unit> the fourth displacement unit> the first displacement unit.

[0214] Table 3

[0215]

[0216] Furthermore, in order to improve the displacement effect of the residual oil in each displacement unit, in the embodiment of this specification, before the displacement systems of each displacement unit are sequentially injected according to the displacement sequence, it further includes:

[0217] dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is greater than or equal to a first oil recovery efficiency threshold as a plugging layer;

[0218] The blocking layer is blocked or protected from radiation.

[0219] That is, the plugging layer with an oil displacement efficiency greater than 45% is not the target of the polymer flooding production method for heterogeneous oil reservoirs provided in the embodiments of this specification. Before polymer injection into other displacement units, the old wells in the plugging layer are first plugged, and new wells are protected from injection to eliminate the interference of the pore throat structure of the plugging layer on the injection of other displacement units.

[0220] Further, in the embodiment of this specification, in step S140: injecting the displacement system of each displacement unit in sequence according to the displacement sequence can be further performed as follows:

[0221] Furthermore, if Figure 6 As shown, in the embodiment of this specification, in step S140, determining the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence further includes:

[0222] S610: Calculating a displacement pressure change rate according to the displacement pressure change curve;

[0223] S620: When the pressure change rate is less than a preset pressure change rate threshold, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

[0224] When the displacement system is just injected into its corresponding displacement unit, the displacement system quickly fills into the pore throat structure of the displacement unit, and the displacement pressure change rate increases rapidly; and as the displacement system continues to advance, the pore throat structure of the displacement unit is gradually filled, the displacement system advances slower, and the displacement pressure change rate decreases rapidly. Therefore, when the displacement pressure change rate decreases to a preset pressure change rate threshold, it can be judged that the current displacement unit has completed displacement and the next displacement unit can be displaced, that is, it is judged that the displacement unit located after the current displacement unit in the displacement sequence has arrived at the injection time of the displacement system injection.

[0225] Furthermore, if Figure 7 As shown, in some preferred embodiments, the injection timing of the displacement system of the next displacement unit is determined according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, further comprising:

[0226] S710: Calculating a displacement pressure change rate according to the displacement pressure change curve;

[0227] S720: When the pressure change rate is less than a preset pressure change rate threshold and is maintained for a preset time, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

[0228] That is, it is to avoid the instantaneous situation that the pressure change rate is less than the preset pressure change rate threshold, thereby improving the accuracy of judging the injection timing of the displacement system for each displacement unit, which is beneficial to improving the displacement effectiveness of the displacement system.

[0229] like Figure 8 As shown, the embodiment of this specification also provides a non-homogeneous reservoir polymer flooding production device, including:

[0230] A division module 81 is used to divide the target heterogeneous oil reservoir into a plurality of displacement units according to the oil displacement efficiency;

[0231] A first determination module 82 is used to determine the polymer displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure;

[0232] A second determination module 83, used to determine a displacement order of the plurality of displacement units;

[0233] The displacement module 84 is used to sequentially inject the displacement systems of the displacement units according to the displacement sequence, and determine the injection timing of the displacement system of the subsequent displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to exploit each displacement unit.

[0234] like Fig. 9 As shown, the division module 81 includes:

[0235] A first division unit 811 is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold;

[0236] The second division unit 812 is used to divide the area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold into a second displacement unit.

[0237] like Fig.10 As shown, in another feasible embodiment, the division module 81 includes:

[0238] A first division unit 811 is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold;

[0239] A second division unit 812 is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a second oil recovery efficiency threshold and greater than or equal to a third oil recovery efficiency threshold into a second displacement unit, wherein the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold;

[0240] A third division unit 813 is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and greater than or equal to a fourth oil recovery efficiency threshold into a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; and

[0241] The fourth division unit 814 is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold into a fourth displacement unit, and the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold.

[0242] like Fig.11 As shown, the first determining module 82 further includes:

[0243] The molecular weight determination unit 821 is used to determine the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit;

[0244] The injection concentration determination unit 822 is used to calculate the injection concentration of each displacement system according to the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit;

[0245] The injection volume determination unit 823 is used to calculate the injection volume of each displacement system according to the injection concentration of each displacement system and the injection concentration-injection volume relationship curve;

[0246] The injection pressure determination unit 824 is used to determine the injection pressure of each displacement system according to the molecular weight, injection concentration and injection volume of each displacement system.

[0247] The beneficial effects obtained by the device provided in the embodiments of this specification are consistent with the beneficial effects obtained by the above method and will not be repeated here.

[0248] like Fig.12As shown, a computer device provided in an embodiment of this specification, a heterogeneous reservoir polymer flooding production device in this specification can be a computer device in this embodiment, executing the above method of this specification. The computer device 1202 may include one or more processors 1204, such as one or more central processing units (CPUs), each of which may implement one or more hardware threads. The computer device 1202 may also include any memory 1206, which is used to store any kind of information such as code, settings, data, etc. Non-limiting, for example, the memory 1206 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent a fixed or removable component of the computer device 1202. In one case, when the processor 1204 executes an associated instruction stored in any memory or combination of memories, the computer device 1202 may perform any operation of the associated instruction. The computer device 1202 also includes one or more drive mechanisms 1208 for interacting with any storage, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0249] The computer device 1202 may also include an input / output module 1210 (I / O) for receiving various inputs (via input devices 1212) and for providing various outputs (via output devices 1214). A specific output mechanism may include a presentation device 1216 and an associated graphical user interface (GUI) 1218. In other embodiments, the input / output module 1210 (I / O), input device 1212, and output device 1214 may not be included, and the computer device 1202 may be used as a computer device in a network. The computer device 1202 may also include one or more network interfaces 1220 for exchanging data with other devices via one or more communication links 1222. One or more communication buses 1224 couple the components described above together.

[0250] The communication link 1222 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 1222 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0251] Corresponding to Figures 1 to 3 and Figure 6In addition to the method shown, an embodiment of the specification also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are executed.

[0252] The embodiment of the present specification also provides a computer-readable instruction, wherein when the processor executes the instruction, the program therein causes the processor to execute the following Figures 1 to 3 and Figure 6 The method shown.

[0253] The embodiments of the present specification also provide a computer program product, including at least one instruction or at least one program, wherein the at least one instruction or the at least one program is loaded and executed by a processor to implement the following Figures 1 to 3 and Figure 6 The method shown.

[0254] It should be understood that in the various embodiments of this specification, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0255] It should also be understood that in the embodiments of this specification, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this specification generally indicates that the associated objects before and after are in an "or" relationship.

[0256] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this specification can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this specification.

[0257] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0258] In the several embodiments provided in this specification, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or it can be an electrical, mechanical or other form of connection.

[0259] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this specification.

[0260] In addition, each functional unit in each embodiment of this specification may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0261] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this specification is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this specification. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0262] Specific embodiments are used in this specification to illustrate the principles and implementation methods of this specification. The description of the above embodiments is only used to help understand the methods and core ideas of this specification. At the same time, for those skilled in the art, according to the ideas of this specification, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this specification.

Claims

1. A polymer flooding method for heterogeneous oil reservoirs, characterized in that: include: According to the oil displacement efficiency, the target heterogeneous reservoir is divided into multiple displacement units; Determining a polymer displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure; determining a displacement order of the plurality of displacement units; The displacement systems of the displacement units are injected sequentially according to the displacement sequence, and the injection timing of the displacement system of the subsequent displacement unit is determined according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to produce each displacement unit.

2. The polymer flooding method for heterogeneous oil reservoirs according to claim 1, characterized in that: According to the oil displacement efficiency, the target heterogeneous reservoir is divided into multiple displacement units, further including: dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and greater than or equal to a second oil recovery efficiency threshold as a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold; The area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold is divided into a second displacement unit.

3. The polymer flooding method for heterogeneous oil reservoirs according to claim 2, characterized in that: Determine the displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure, including: Determining the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit; Calculate the injection concentration of each displacement system according to the viscosity of crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit; According to the injection concentration of each displacement system and the relationship curve between injection concentration and injection volume, the injection volume of each displacement system is calculated; The injection pressure of each displacement system is determined according to the molecular weight, injection concentration and injection volume of each displacement system.

4. The polymer flooding method for heterogeneous oil reservoirs according to claim 3, characterized in that: The injection concentration of each displacement system is calculated based on the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit, further comprising: Calculating the surface viscosity of the displacement system according to the crude oil viscosity of the target heterogeneous oil reservoir; The injection concentration of each displacement system is calculated based on the surface viscosity of the displacement system and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system.

5. The polymer flooding method for heterogeneous oil reservoirs according to claim 4, characterized in that: The calculation formula of the surface viscosity of the displacement system is: Among them, μ 地面 is the surface viscosity of the displacement system, μ 地下 is the underground viscosity of the displacement system; A is the formation shear viscosity loss; B is the shear viscosity loss of the surface pipe network system; μ 地下 =Cμ 原油 ; Among them, μ 原油 is the crude oil viscosity of the heterogeneous oil reservoir, and C is a constant coefficient greater than 0.

6. The polymer flooding method for heterogeneous oil reservoirs according to claim 3, characterized in that: The method further comprises: dividing the area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than the second oil recovery efficiency threshold into a second displacement unit; dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a second oil recovery efficiency threshold and greater than or equal to a third oil recovery efficiency threshold as a second displacement unit, wherein the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold; dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and greater than or equal to a fourth oil recovery efficiency threshold as a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; and A region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold is divided into a fourth displacement unit, and the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold.

7. The polymer flooding method for producing heterogeneous oil reservoirs according to claim 6, characterized in that: The viscosity-concentration relationship curve corresponding to the molecular weight of each displacement unit displacement system is obtained by the following method: A plurality of core samples are obtained from a plurality of different displacement units of a plurality of heterogeneous oil reservoirs with different crude oil viscosities, and the oil displacement efficiencies of the different displacement units are different; The displacement system was used to perform polymer flooding on each core sample with different molecular weights and different injection concentrations; Obtain the change value of the remaining oil saturation of each core sample before and after the completion of polymer flooding; Determining the molecular weight of the displacement system that matches the oil displacement efficiency of each displacement unit according to the residual oil saturation change value; Determining the injection concentration of the displacement system adapted to each displacement unit according to the molecular weight of the displacement system adapted to the oil displacement efficiency of each displacement unit and the residual oil saturation change value; According to the injection concentration of the displacement system matched with each displacement unit and the crude oil viscosity of the heterogeneous oil reservoir corresponding to each displacement unit, a viscosity-concentration relationship curve corresponding to the molecular weight of the displacement system of each displacement unit is fitted.

8. The polymer flooding production method for heterogeneous oil reservoirs according to claim 7, characterized in that: The injection concentration of each displacement system is calculated based on the surface viscosity of the displacement system and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit, further comprising: The injection concentration of the first displacement unit is calculated according to the following viscosity-concentration relationship curve: The injection concentration of the second displacement unit is calculated according to the following viscosity-concentration relationship curve: The injection concentration of the third displacement unit is calculated according to the following viscosity-concentration relationship curve: The injection concentration of the fourth displacement unit is calculated according to the following viscosity-concentration relationship curve: Among them, μ 地面 is the surface viscosity of the displacement system, and x1, x2, x3 and x4 are the injection concentrations of the displacement systems of the first displacement unit, the second displacement unit, the third displacement unit and the fourth displacement unit, respectively.

9. The polymer flooding production method for heterogeneous oil reservoirs according to claim 3, characterized in that: The relationship curve between the injection concentration and the injection volume is: x i =kv i +b; Among them, x i is the injection concentration of the displacement system of the ith displacement unit, in mg / L; v i is the injection volume of the displacement system of the ith displacement unit, in PV; k is the fitting slope, and b is the fitting intercept.

10. The polymer flooding production method for heterogeneous oil reservoirs according to claim 2, characterized in that: Before the displacement systems of the displacement units are sequentially injected according to the displacement sequence, the method further comprises: dividing a region in the target heterogeneous oil reservoir whose oil recovery efficiency is greater than or equal to a first oil recovery efficiency threshold as a plugging layer; The blocking layer is blocked or protected from radiation.

11. The polymer flooding method for heterogeneous oil reservoirs according to claim 1, characterized in that: Determining the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence further includes: Calculating the displacement pressure change rate according to the displacement pressure change curve; When the pressure change rate is less than a preset pressure change rate threshold, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

12. The polymer flooding production method for heterogeneous oil reservoirs according to claim 1, characterized in that: Determining the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence further includes: Calculating the displacement pressure change rate according to the displacement pressure change curve; When the pressure change rate is less than a preset pressure change rate threshold and is maintained for a preset time, it is determined that the injection timing of the displacement system of the next displacement unit has arrived.

13. The polymer flooding method for heterogeneous oil reservoirs according to claim 1, characterized in that: The oil displacement efficiency is calculated by the following formula: Where ED is the oil recovery efficiency; S or is the residual oil saturation of the target heterogeneous reservoir after water flooding; S o is the oil saturation of the target heterogeneous oil reservoir before water flooding.

14. A polymer flooding production device for heterogeneous oil reservoirs, characterized in that: include: A partitioning module is used to divide the target heterogeneous reservoir into a plurality of displacement units according to the oil displacement efficiency; A first determination module is used to determine the polymer displacement system of each displacement unit, wherein the displacement system of each displacement unit has different molecular weight, injection concentration, injection volume and injection pressure; A second determination module, used to determine a displacement order of the plurality of displacement units; The displacement module is used to sequentially inject the displacement systems of each displacement unit according to the displacement sequence, and determine the injection timing of the displacement system of the next displacement unit according to the displacement pressure change curve of the previous displacement unit in the displacement sequence, so as to mine each displacement unit.

15. The polymer flooding production device for heterogeneous oil reservoirs according to claim 14, characterized in that: The division module comprises: A first division unit is used to divide a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and is greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold; The second division unit is used to divide the area in the target heterogeneous oil reservoir where the oil recovery efficiency is less than a second oil recovery efficiency threshold into a second displacement unit.

16. The polymer flooding production device for heterogeneous oil reservoirs according to claim 14, characterized in that: The division module comprises: A first division unit is used to divide a region in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a first oil recovery efficiency threshold and is greater than or equal to a second oil recovery efficiency threshold into a first displacement unit, wherein the second oil recovery efficiency threshold is less than the first oil recovery efficiency threshold; A second division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a second oil recovery efficiency threshold and is greater than or equal to a third oil recovery efficiency threshold into a second displacement unit, wherein the third oil recovery efficiency threshold is less than the second oil recovery efficiency threshold; A third division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a third oil recovery efficiency threshold and is greater than or equal to a fourth oil recovery efficiency threshold into a third displacement unit, wherein the fourth oil recovery efficiency threshold is less than the third oil recovery efficiency threshold; and The fourth division unit is used to divide the area in the target heterogeneous oil reservoir whose oil recovery efficiency is less than a fourth oil recovery efficiency threshold and greater than or equal to a fifth oil recovery efficiency threshold into a fourth displacement unit, and the fifth oil recovery efficiency threshold is less than the fourth oil recovery efficiency threshold.

17. The polymer flooding production device for heterogeneous oil reservoirs according to claim 14, characterized in that: The first determining module also includes: A molecular weight determination unit, used to determine the molecular weight of each displacement system according to the oil displacement efficiency of each displacement unit; An injection concentration determination unit, used to calculate the injection concentration of each displacement system according to the viscosity of the crude oil in the target heterogeneous oil reservoir and the viscosity-concentration relationship curve corresponding to the molecular weight of each displacement system of the displacement unit; An injection volume determination unit, used to calculate the injection volume of each displacement system according to the injection concentration of each displacement system and the injection concentration-injection volume relationship curve; The injection pressure determination unit is used to determine the injection pressure of each displacement system according to the molecular weight, injection concentration and injection volume of each displacement system.

18. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 13 is implemented.

19. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 13 is implemented.

20. A computer program product, characterized in that The method comprises at least one instruction or at least one program, wherein the at least one instruction or the at least one program is loaded and executed by a processor to implement the method according to any one of claims 1 to 13.

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