A method, device and system for evaluating steering performance

Abstract

The application discloses a kind of steering performance evaluation method, device and system, steps are as follows: S1: carry out acid liquid performance evaluation, obtain the viscosity, concentration, peak viscosity, time-dependent viscosity relationship curve of acid liquid;S2: carry out single-axis plugging evaluation, obtain peak viscosity, reservoir permeability, single-axis plugging pressure, single-axis plugging time relationship curve;S3: fracture simulation evaluation, obtain peak viscosity, fracture permeability, fracture plugging pressure, fracture plugging time relationship curve;S4: using CT scanning reservoir core, obtain reservoir core parameters;S5: calculate the steering capacity and plugging time parameters of simulated real reservoir;S6: establish recommended acid liquid formula composition.The application comprehensively considers reservoir characteristics, quantifies pore and fracture volume, uses the steering pressure and time required by process design as requirements, establishes the performance parameters of acid liquid system under reservoir conditions, and considers the quantitative proportion of real reservoir pore and fracture, selects acid liquid system capable of achieving steering pressure.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field exploration and development technology, and more specifically, to a method, apparatus and system for evaluating steering performance. Background Technology

[0002] Heterogeneous oil and gas reservoirs occupy a very important position in the world's oil and gas production and reserves. The heterogeneity of the reservoir is a key factor restricting the improvement of oil and gas reservoir recovery. According to the principle of least resistance, during reservoir stimulation, acid first enters the fractures and high-permeability channels with lower resistance. Acid cannot enter the contaminated and therefore low-permeability reservoirs, making it impossible to achieve uniform stimulation of long well sections of the reservoir and fully realize the reservoir's production capacity.

[0003] Steering measures are a powerful way to improve the effectiveness of acidification measures, and steering performance evaluation is constantly emerging. Currently, existing mechanical steering has problems such as complex processes, high construction difficulty, and high cost. Chemical steering technologies such as foam steering, biodegradable fiber steering, polymer steering, and viscoelastic surfactant steering have advantages such as simple construction, self-steering, strong stability, and low damage, and have been widely used in field construction.

[0004] Current evaluations of steering performance mainly focus on two aspects. For liquid steering, a dual-core flow test device is mainly used to evaluate the steering performance of the acidic fluid by utilizing the modification effect of the acid core. For physical steering, pressure tests are mainly conducted using sealing devices to evaluate the performance of physical steering by utilizing the sealing pressure and time.

[0005] Therefore, existing shift evaluation technologies mainly focus on equipment establishment and shift evaluation research for single reservoir types. Uniaxial plugging evaluation and fracture simulation evaluation can only simulate and evaluate reservoirs in a relatively singular way. However, when actual reservoirs have both fractures and pores, using a single type of reservoir condition for evaluation cannot accurately and effectively simulate real reservoir conditions, making it difficult to effectively evaluate real reservoirs. Therefore, it cannot effectively guide the selection of acid formulation and system for actual reservoirs in the field.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] To overcome the defects and shortcomings of the prior art, this invention provides a new method, device and system for evaluating steering performance. It comprehensively considers the characteristics of the reservoir, as well as the quantitative ratio of the actual reservoir porosity and fractures, and selects an acid system that can reach the steering pressure. This provides a basis for the selection of acid in heterogeneous reservoirs, achieves uniform acid distribution in long well sections, and enhances the transformation of damaged reservoir sections.

[0008] This invention is achieved through the following technical solution:

[0009] A method for evaluating steering performance includes the following steps:

[0010] S1: Conduct acid performance evaluation and obtain the relationship curves between acid viscosity, concentration, peak viscosity, and viscosity change time;

[0011] S2: Uniaxial plugging evaluation, select systems with different peak viscosities, and obtain the relationship curves between peak viscosity, reservoir permeability, uniaxial plugging pressure, and uniaxial plugging time;

[0012] S3: Crack simulation evaluation, selecting systems with different peak viscosities to obtain the relationship curves between peak viscosity, crack permeability, crack plugging pressure, and crack plugging time;

[0013] S4: Use CT scans to obtain the three-dimensional structure, porosity, and fracture parameters of the reservoir core;

[0014] S5: Calculate the steering capability of the simulated real reservoir and the plugging time parameters of the real reservoir;

[0015] S6: Establish the recommended acid system composition, number of injection stages, and acid dosage.

[0016] The specific process of step S1 is as follows:

[0017] A fixed volume of acid solution was prepared, and an acid solution system with a certain concentration was reacted with carbonate rocks.

[0018] With a fixed diverting agent concentration, viscometer tests were conducted at different time points over 170 seconds. -1 The viscosity value at the shear rate is obtained, and the parameters of acid concentration and acid viscosity, and acid viscosity and viscosity change time are obtained. The concentration of the diverting agent is changed, and the above steps are repeated to obtain the parameters of acid concentration and acid viscosity, acid viscosity and viscosity change time again. At the same time, the peak viscosity and viscosity change time parameters are obtained.

[0019] The specific process of step S2 is as follows:

[0020] With the core conditions fixed, a homogeneous aqueous solution of polyacrylamide with the same viscosity as the acid to be evaluated was used to test data under constant flow rate and constant pressure difference. The constant flow rate obtained was the uniaxial standard flow rate, and the constant pressure difference was the uniaxial standard plugging pressure.

[0021] Under uniaxial standard flow rate conditions, with a fixed diverting agent concentration, uniaxial plugging experiments were conducted using acid to obtain uniaxial plugging diverting pressure and uniaxial plugging time parameters. The peak viscosity and uniaxial plugging diverting pressure and uniaxial plugging time parameters were obtained by varying the diverting agent concentration. Permeability reservoirs with different permeabilities were then used to obtain permeability and uniaxial plugging diverting pressure and uniaxial plugging time parameters again. Wherein, uniaxial plugging diverting pressure = uniaxial plugging pressure - uniaxial standard plugging pressure.

[0022] The specific process of step S3 is as follows:

[0023] With the fracture conditions fixed, a homogeneous aqueous solution of polyacrylamide with the same viscosity as the acid to be evaluated was used to test data under constant flow rate and constant pressure difference. The constant flow rate obtained was the standard flow rate of the fracture, and the constant pressure difference was the standard sealing pressure of the fracture.

[0024] Under standard flow velocity conditions in the fracture, with a fixed diverting agent concentration, fracture plugging experiments were conducted using acid to obtain parameters for fracture plugging diverting pressure and fracture plugging time. By varying the fracture height, curves of permeability versus fracture plugging diverting pressure and fracture plugging time were obtained. By varying the diverting agent concentration, parameters of peak viscosity versus fracture plugging diverting pressure and fracture plugging time were obtained. Wherein, fracture plugging diverting pressure = fracture plugging pressure - standard fracture plugging pressure.

[0025] The specific process of step S4 is as follows:

[0026] First, CT scans were used to depict the three-dimensional structure of the rock core that had not been injected with acid. The volume ratio of pores and fractures was calculated, and the equivalent permeability was also calculated.

[0027] Then, CT scans were used to examine the core samples after acid injection, depicting the three-dimensional structure. The volume ratios of pores and fractures were calculated, and the equivalent permeability was also calculated.

[0028] The specific process of step S5 is as follows:

[0029] The actual reservoir's deflection capacity is calculated based on the ratio of uniaxial plugging deflection pressure to pore volume and the ratio of fracture plugging deflection pressure to fracture volume.

[0030] The actual reservoir plugging time is calculated by multiplying the uniaxial plugging time by the percentage of pore volume and the fracture plugging time by the percentage of fracture volume.

[0031] The specific process of step S6 is as follows:

[0032] Based on the process design requirements, determine the steering capability value and plugging time of the process design;

[0033] Under the given actual reservoir permeability and type, the corresponding actual reservoir diversion capacity and plugging time values ​​for different acid formulations are selected. The acid formulation with a difference of 10% between the actual reservoir diversion capacity and the process design diversion capacity is selected as the recommended acid system.

[0034] By comparing the plugging time of the recommended acid system with that of the process design, if the plugging time of the recommended acid system is longer than that of the process design, then the acid system is adopted; if the plugging time of the recommended acid system is shorter than that of the process design, then another acid system with stronger plugging capacity is selected to ensure that the difference between the plugging time of the recommended acid system and the plugging time of the process design is within 10%, while ensuring that the actual reservoir diversion capacity is greater than the temporary plugging pressure designed by the process.

[0035] An evaluation device used in a steering performance evaluation method includes an injection module, a core seepage module, and a recording module; the injection module includes a two-way injection pump and a storage tank.

[0036] The core seepage module includes cylindrical cores and cubic cores. The cylindrical core seepage module has core diameters that can be switched in parallel between 2.54cm, 5.0cm and 8cm, with a maximum length of 20cm. The cubic core seepage module has a rock slab inlet width of 8cm, 10cm and 12cm, a height of 0.1mm-15mm, and a length that varies between 15cm, 20cm and 25cm.

[0037] The recording module is used to record temperature, pressure, flow rate, time, and rock and acid performance parameters;

[0038] Pressure measuring points are set at the entrance and exit of cylindrical and cubic cores, with at least 2 cm intervals between them, and generally 2-4 pressure measuring points are set in the middle.

[0039] An evaluation system for a steering performance evaluation method is characterized by comprising a data calculation and analysis module and a data output module; the data calculation and analysis module analyzes and evaluates the performance parameters of the selected acid system, and automatically identifies and highlights the highest peak pressure and sealing time; the data output module can simultaneously output various curves and data, and also provides graphical output of peak pressure and sealing time parameters.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] 1. The present invention provides a method, apparatus and system for evaluating steering performance, which comprehensively considers the characteristics of the reservoir and quantifies its porosity (including pores) and fracture volume. Based on the steering pressure and steering time required by the process design, the performance parameters of the acid system under reservoir conditions are established by comparison. At the same time, the quantitative ratio of porosity and fracture in the actual reservoir is considered, and an acid system that can achieve the steering pressure is selected.

[0042] 2. The steering performance evaluation method, device and system provided in the embodiments of the present invention are reliable in principle and accurate in results. They can improve the selection criteria for acid in heterogeneous reservoirs, achieve uniform acid distribution in long well sections, and enhance the transformation of damaged reservoir sections. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A graph showing the relationship between acid concentration and viscosity provided in an embodiment of the present invention;

[0045] Figure 2 A graph showing the relationship between acid viscosity and viscosity change time provided in an embodiment of the present invention;

[0046] Figure 3 A graph showing the relationship between peak viscosity and viscosity change time is provided for an embodiment of the present invention.

[0047] Figure 4 A graph showing the relationship between single-axis plugging steering pressure and single-axis plugging time provided in an embodiment of the present invention;

[0048] Figure 5 A graph showing the relationship between peak viscosity and uniaxial plugging steering pressure provided for embodiments of the present invention;

[0049] Figure 6 A graph showing the relationship between peak viscosity and uniaxial plugging time provided in an embodiment of the present invention;

[0050] Figure 7 A graph showing the relationship between permeability and uniaxial plugging turning pressure is provided for embodiments of the present invention.

[0051] Figure 8 A graph showing the relationship between permeability and uniaxial plugging time provided in an embodiment of the present invention;

[0052] Figure 9A graph showing the relationship between crack sealing turning pressure and crack sealing time provided in an embodiment of the present invention;

[0053] Figure 10 A graph showing the relationship between fracture permeability and fracture sealing diversion pressure provided in an embodiment of the present invention;

[0054] Figure 11 A graph showing the relationship between crack permeability and crack sealing time provided in an embodiment of the present invention;

[0055] Figure 12 A graph showing the relationship between peak viscosity and crack sealing turning pressure provided in an embodiment of the present invention;

[0056] Figure 13 The graph showing the relationship between peak viscosity and crack sealing time is provided for an embodiment of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0058] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0059] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] In the description of this invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0061] Example 1

[0062] An embodiment of the present invention provides a steering performance evaluation method, comprising the following steps:

[0063] S1: Conduct acid performance evaluation and obtain the relationship curves between acid viscosity, concentration, peak viscosity, and viscosity change time;

[0064] S2: Uniaxial plugging evaluation, select systems with different peak viscosities, and obtain the relationship curves between peak viscosity, reservoir permeability, uniaxial plugging pressure, and uniaxial plugging time;

[0065] S3: Crack simulation evaluation, selecting systems with different peak viscosities to obtain the relationship curves between peak viscosity, crack permeability, crack plugging pressure, and crack plugging time;

[0066] S4: Use CT scans to obtain the three-dimensional structure, porosity, and fracture parameters of the reservoir core;

[0067] S5: Calculate the steering capability of the simulated real reservoir and the plugging time parameters of the real reservoir;

[0068] S6: Establish the recommended acid system composition, number of injection stages, and acid dosage.

[0069] 1.1 The specific process for evaluating the performance of acid is as follows:

[0070] 1.1.1 With a fixed acid volume, an acid system of a certain acid concentration was prepared, and the amount of carbonate rock required at the acid reaction concentration was calculated. Pure carbonate rock was used in excess by 35% of its mass for the reaction.

[0071] 1.1.2 Fixed diverting agent concentration: Select a diverting agent concentration of 2%, 3%, 4%, ..., 8%. In this example, 4% is selected. Prepare a 20% hydrochloric acid mass concentration solution. The rock is a 0.5cm long cube of fixed component. The position of the rock in the acid solution is fixed. Place it in a constant temperature water bath at 90℃ for reaction.

[0072] 1.1.3 Take 200ml of acid solution and test it with a viscometer for 170s. -1 The initial viscosity value at the shear rate was determined, and then the viscosity and concentration of the acid solution were tested at different reaction times until the change between two adjacent test values ​​was less than 10% or less than 5 mPa·s, at which point the experiment was stopped.

[0073] 1.1.4 Obtain the acid concentration and viscosity, and the acid viscosity and viscosity change time parameters; change the concentration of the diverting agent, repeat the above steps, and obtain the acid concentration and viscosity, and the acid viscosity and viscosity change time parameters again, while obtaining the peak viscosity and viscosity change time parameters; the peak viscosity is the highest viscosity value during the viscosity change process at different times under the same formulation (i.e., the concentrations of hydrochloric acid and diverting agent are fixed), and the acid viscosity change time is the time interval between the initial viscosity after the reaction and the initial viscosity before the reaction.

[0074] 1.2 The specific process of single-axis plugging evaluation is as follows:

[0075] 1.2.1 With fixed core conditions, a linear polyacrylamide aqueous solution with a molecular weight of 8.5 million was used. The viscosity was the same as the initial viscosity value of 12 mPa·s tested under a fixed diverting agent concentration. The standard procedure for testing core permeability according to SY / T 5358-2010 was used to test the permeability of the core under constant pressure difference at both ends of the core under stable flow conditions. The constant flow rate of 1 ml / min was recorded as the uniaxial standard flow rate, and the constant pressure difference of 0.63 MPa was recorded as the uniaxial standard plugging pressure.

[0076] 1.2.2 After the test, a dissolution injection method was used to degrade the linear polyacrylamide aqueous solution, so that the core permeability was restored to the initial state before the aqueous solution was injected; or the same core was used to carry out subsequent experiments.

[0077] 1.2.3 Using treated core samples or similar core samples, a diverting acid plugging experiment was conducted. At a standard uniaxial flow rate of 1 ml / min, with a fixed diverting agent concentration, the standard procedure for testing core permeability (SY / T 5358-2010) was used to test the pressure difference across the core. The relationship between pressure and time was recorded, and the uniaxial plugging diverting pressure and uniaxial plugging time parameters were obtained. The highest plugging pressure value was the peak pressure during the test. Timing began when the test pressure exceeded the standard plugging pressure and ended when the test pressure decreased to the standard plugging pressure. This time difference was the uniaxial plugging time. The volume of acid used in the experiment was measured.

[0078] 1.2.4 By varying the concentration of the diverting agent, the peak viscosity and the parameters of uniaxial plugging diverting pressure and uniaxial plugging time were obtained; by varying reservoirs with different permeability, the parameters of permeability and uniaxial plugging diverting pressure and uniaxial plugging time were obtained again.

[0079] 1.3 The specific process of crack simulation evaluation is as follows:

[0080] 1.3.1 Fixed fracture conditions: fracture width 5cm, height 0.2mm, and length 8cm. A linear polyacrylamide aqueous solution with a molecular weight of 8.5 million was used, with a viscosity the same as the initial viscosity value of 12mPa·s under a fixed diverting agent concentration. The standard procedure for testing core permeability according to SY / T 5358-2010 was adopted. The constant pressure difference between the two ends of the fracture was tested under stable flow conditions, and the equivalent permeability of the fracture was obtained. The constant flow rate of 5ml / min was recorded as the standard flow rate of the fracture, and the constant pressure difference of 1.2MPa was recorded as the standard sealing pressure of the fracture.

[0081] 1.3.2 At a standard flow rate of 5 ml / min in the fracture, with a fixed concentration of the diverting agent, a fracture plugging experiment was conducted using diverting acid to obtain the parameters of fracture plugging diverting pressure and fracture plugging time. The highest plugging pressure value of 2.89 MPa was the peak pressure during the test. At the same flow rate, timing started when the test pressure was 1.2 MPa higher than the standard plugging pressure injected into the fracture and ended when the test pressure decreased to the standard plugging pressure of the fracture. This time difference of 42 min was the fracture plugging time. The volume of acid used in the measurement experiment was 220 ml.

[0082] 1.3.3 By varying the fracture height, obtain curves of permeability versus fracture plugging turning pressure and fracture plugging time; by varying the turning agent concentration, obtain peak viscosity versus fracture plugging turning pressure and fracture plugging time parameters; where fracture plugging turning pressure = fracture plugging pressure - fracture standard plugging pressure.

[0083] 1.4 Data Processing:

[0084] 1.4.1 Under conditions of diverting agent concentrations of 2%, 3%, 4%, ..., 8%, respectively, based on the parameters obtained in steps 1.1-1.3, establish the relationship curve between acid concentration and viscosity. In this curve, the diverting agent concentration is selected as 4%, and curve 1 is established. Figure 1 As shown in Figure 2, curves 2 were established to show the relationship between different acid viscosities and viscosity change time. Figure 2 As shown; curves 3, representing the viscosity peak and viscosity time, were established under different concentrations of the aforementioned diverting agents, as shown. Figure 3 As shown.

[0085] 1.4.2 At a fixed steering agent concentration of 4%, a curve was established showing the relationship between single-axle plugging steering pressure and single-axle plugging time, as shown in Figure 4. Figure 4 As shown; under different concentrations of the aforementioned steering agent, curves 5 (peak viscosity vs. uniaxial plugging steering pressure) and 6 (peak viscosity vs. uniaxial plugging time) were established, as shown. Figure 5-6 As shown; by varying reservoir cores with different permeabilities, curves 7 and 8 were established to show the relationship between permeability and uniaxial plugging turning pressure, and between permeability and uniaxial plugging time. Figure 7-8 As shown;

[0086] 1.4.3 At a fixed diversion agent concentration of 4%, a curve was established for the relationship between crack sealing diversion pressure and crack sealing time, as shown in Figure 9. Figure 9 As shown; by varying the fracture height, curves 10 and 11 are established for permeability versus fracture plugging pressure and permeability versus fracture plugging time; by varying the concentrations of the other diverting agents mentioned above, curves 12 and 13 are established for peak viscosity versus fracture plugging pressure and peak viscosity versus fracture plugging time, as shown. Figure 10-13 As shown.

[0087] 1.5CT scan

[0088] 1.5.1 A CT scanner was used to scan the rock core before and after the experiment. The volume ratio of pores and fractures was calculated, and the equivalent permeability was calculated. The change in equivalent permeability before and after the experiment is the improvement in permeability.

[0089] 1.5.2 Combine CT scan core results or field logging data to calculate the volume ratio of pores (including voids) and fractures. Combine this with the established curves 1-8 to select the equivalent permeability curves under the pore and fracture conditions corresponding to the core.

[0090] 1.5.3 The directional ability of a real reservoir is simulated by using the ratio of uniaxial plugging directional pressure * pore volume percentage + fracture plugging directional pressure * fracture volume percentage.

[0091] 1.5.4 The sealing time of a real reservoir is simulated by using uniaxial sealing time * pore volume percentage + fracture sealing time * fracture volume percentage.

[0092] 1.6 The recommended acid system composition, number of injection stages, and acid volume are as follows:

[0093] 1.6.1 Based on the process design requirements, the required steering capacity value for the process design shall exceed 0.25 MPa / cm, and the sealing time shall be greater than 25 min;

[0094] 1.6.2 With a real reservoir permeability matrix of 1.35 mD and fracture of 5.61 mD, and with pore and fracture volume ratios of 75% and 25% respectively, the real reservoir diversion capacity and plugging time of different acid formulations were obtained. The acid formulation with a difference of less than 10% between the real reservoir diversion capacity and the process design diversion capacity was selected as the recommended acid system.

[0095] 1.6.3 Under the premise of meeting the reversal capability, compare the plugging time of the recommended acid system and the process design. If the plugging time of the recommended acid system is greater than the plugging time of the process design, then the acid system shall be adopted; if the plugging time of the recommended acid system is less than the plugging time of the process design, then another acid system with stronger plugging capability shall be selected to ensure that the difference between the plugging time of the recommended acid system and the plugging time of the process design is within 10%, and at the same time ensure that the actual reservoir reversal capability is greater than the temporary plugging pressure designed by the process.

[0096] Example 2

[0097] The evaluation device used in the steering performance evaluation method provided in this embodiment of the invention includes an injection module, a core seepage module, and a recording module; the injection module includes a two-way injection pump and a storage tank;

[0098] The core seepage module includes cylindrical cores and cubic cores. The cylindrical core seepage module has core diameters that can be switched in parallel between 2.54cm, 5.0cm and 8cm, with a maximum length of 20cm. The cubic core seepage module has a rock slab inlet width of 8cm, 10cm and 12cm, a height of 0.1mm-15mm, and a length that varies between 15cm, 20cm and 25cm.

[0099] The recording module is used to record temperature, pressure, flow rate, time, and rock and acid performance parameters;

[0100] Pressure measuring points are set at the entrance and exit of cylindrical and cubic cores, with at least 2 cm intervals between them, and generally 2-4 pressure measuring points are set in the middle.

[0101] Example 3

[0102] The evaluation system used in the steering performance evaluation method provided in this embodiment of the invention includes a data calculation and analysis module and a data output module. The data calculation and analysis module analyzes and evaluates the performance parameters of the selected acid system and automatically identifies and highlights the highest peak pressure and sealing time. The data output module can simultaneously output various curves and data, and also provides graphical output of the peak pressure and sealing time parameters.

[0103] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating steering performance, characterized in that, Includes the following steps: S1: Conduct acid performance evaluation and obtain the relationship curves between acid viscosity, concentration, peak viscosity, and viscosity change time; S2: Uniaxial plugging evaluation, select systems with different peak viscosities, and obtain the relationship curves between peak viscosity, reservoir permeability, uniaxial plugging pressure, and uniaxial plugging time; The specific process is as follows: With the core conditions fixed, a homogeneous aqueous solution of polyacrylamide with the same viscosity as the acid to be evaluated was used. The standard procedure for testing core permeability, SY / T5358-2010, was adopted to test the constant pressure difference at both ends of the core under stable flow conditions and obtain the permeability of the core. The constant flow rate was recorded as the uniaxial standard flow rate and the constant pressure difference was recorded as the uniaxial standard plugging pressure. Under uniaxial standard flow rate conditions and with a fixed diverting agent concentration, uniaxial plugging experiments were conducted using acid to obtain the relationship curves between uniaxial plugging diverting pressure and uniaxial plugging time. By varying the diverting agent concentration, the relationship curves between peak viscosity and uniaxial plugging diverting pressure and uniaxial plugging time were obtained. Furthermore, by varying reservoirs with different permeability, the relationship curves between permeability and uniaxial plugging diverting pressure and uniaxial plugging time were obtained again. Wherein, uniaxial plugging diverting pressure = uniaxial plugging pressure - uniaxial standard plugging pressure; uniaxial plugging time is the time difference from when the test pressure is higher than the injected standard plugging pressure until the test pressure decreases to the standard plugging pressure. S3: Crack simulation evaluation, selecting systems with different peak viscosities to obtain the relationship curves between peak viscosity, crack permeability, crack plugging pressure, and crack plugging time; The specific process is as follows: With the fracture conditions fixed, a homogeneous aqueous solution of polyacrylamide with the same viscosity as the acid to be evaluated was used. The standard procedure for testing core permeability, SY / T5358-2010, was adopted to test the constant pressure difference at both ends of the fracture under stable flow conditions and obtain the equivalent permeability of the fracture. The constant flow rate was recorded as the standard flow rate of the fracture, and the constant pressure difference was recorded as the standard sealing pressure of the fracture. Under standard flow velocity conditions in the fracture, with a fixed diverting agent concentration, fracture plugging experiments were conducted using acid to obtain the relationship curve between fracture plugging diverting pressure and fracture plugging time. By varying the fracture height, curves were obtained showing the relationship between permeability and fracture plugging diverting pressure and fracture plugging time. Similarly, by varying the diverting agent concentration, curves were obtained showing the relationship between peak viscosity and fracture plugging diverting pressure and fracture plugging time. The fracture plugging diverting pressure is defined as the fracture plugging pressure minus the standard fracture plugging pressure. The fracture plugging time is the time difference between when the test pressure is higher than the injected fracture standard plugging pressure and when the test pressure decreases to the fracture standard plugging pressure. S4: Use CT scans to obtain the three-dimensional structure, porosity, and fracture parameters of the reservoir core; S5: Calculate the steering capability and sealing time parameters of the simulated real reservoir: The actual reservoir's deflection capacity is calculated based on the ratio of uniaxial plugging deflection pressure to pore volume and the ratio of fracture plugging deflection pressure to fracture volume. The actual reservoir plugging time is calculated by multiplying the uniaxial plugging time by the percentage of pore volume and the fracture plugging time by the percentage of fracture volume. S6: Establish the recommended acid system composition, number of injection stages, and acid dosage.

2. The steering performance evaluation method according to claim 1, characterized in that, The specific process of step S1 is as follows: A fixed volume of acid solution was prepared, and an acid solution system with a certain concentration was reacted with carbonate rocks. With a fixed diverting agent concentration, viscometer tests were conducted at different time points over 170 seconds. -1 The viscosity value at the shear rate was obtained, and the relationship curves between acid concentration and acid viscosity, and between acid viscosity and viscosity change time were obtained. The concentration of the diverting agent was changed, and the above steps were repeated to obtain the relationship curves between acid concentration and acid viscosity, between acid viscosity and viscosity change time, and the relationship curve between peak viscosity and viscosity change time were also obtained.

3. The steering performance evaluation method according to claim 1, characterized in that, The specific process of step S4 is as follows: First, CT scans were used to depict the three-dimensional structure of the rock core that had not been injected with acid. The volume ratio of pores and fractures was calculated, and the equivalent permeability was also calculated. Then, CT scans were used to depict the three-dimensional structure of the rock core after acid injection, and the volume ratio of pores and fractures was calculated, as well as the equivalent permeability.

4. The steering performance evaluation method according to claim 1, characterized in that, The specific process of step S6 is as follows: Based on the process design requirements, determine the steering capability value and plugging time of the process design; Select the actual reservoir permeability and reservoir type, obtain the actual reservoir diversion capacity and plugging time values ​​corresponding to different acid formulations, and select the acid formulation with the difference between the actual reservoir diversion capacity and the process design diversion capacity within 10% as the recommended acid system. Then, the plugging time of the recommended acid system and the process design are compared. If the plugging time of the recommended acid system is greater than the plugging time of the process design, then the acid system is adopted. If the plugging time of the recommended acid system is less than the plugging time of the process design, then another acid system with stronger plugging capacity is selected to ensure that the difference between the plugging time of the recommended acid system and the plugging time of the process design is within 10%, while ensuring that the actual reservoir diversion capacity is greater than the temporary plugging pressure designed by the process.

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