Method and equipment for optimizing acidification of carbonate rock horizontal well

Abstract

The invention discloses an optimization method and equipment for acidification of a carbonate rock horizontal well, and relates to the technical field of oil and gas field yield increase renovation, and the key points of the technical scheme are as follows: the carbonate rock horizontal well is divided into a plurality of well sections with similar physical properties according to pre-configured well section conditions in combination with equivalent permeability; calculating the buffer distance of the slug of each well section according to the injection flow of the acid liquid, the diameter of the open hole and the expected retention time of the reaction of the acid liquid and the rock, and determining the design length of the slug according to the buffer distance; calculating the diffusion index of the acid liquor in each well section according to the viscosity of the acid liquor, the local pressure drop gradient of the acid liquor flowing in the channel direction in the reservoir and the local permeability; the coupling relation among the acid liquor reaction retention time, the oil pipe moving speed and the well section length is built, and the injection rate of the oil pipe for injecting the acid liquor is adjusted according to the coupling relation; and selecting an equivalent acid injection strategy or a differential acid injection strategy to optimize the acid liquid injection of each section of the horizontal well.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field stimulation and reconstruction, more particularly, it relates to a carbonate rock horizontal well acidification optimization method and device. BACKGROUND

[0002] Carbonate rock reservoir is one of the important oil and gas storage media in the world, which has multiple percolation channel structures such as fractures, pores and caves. However, such reservoirs usually exhibit obvious heterogeneity, especially in long horizontal wells with a horizontal section length of more than 1000 meters, the reservoir permeability difference is significant, and phenomena such as rapid breakthrough in high permeability area and insufficient reconstruction in low permeability section often occur, which seriously affects the effectiveness and uniformity of acidification reconstruction.

[0003] At present, carbonate rock reservoir acidification mainly relies on the reaction of acid and rock to generate high conductivity channels to improve the permeability and productivity of the near wellbore. However, the traditional acidification process mostly adopts single continuous pumping mode, which easily leads to the preferential entry of acid into high permeability channels in strong heterogeneous reservoirs, resulting in the problem of "non-uniform acidification" such as concentrated acid etching and difficult reconstruction in low permeability areas. In addition, for long horizontal well operations, the acid has a large along-the-way friction in the wellbore, and the acid advancing front is easy to lose control, further exacerbating the uneven spatial distribution of acidification efficiency.

[0004] In order to improve the acidification distribution, some existing technologies propose methods such as multi-section temporary plugging and steering, mechanical well section tools, etc., but there are problems such as unstable plug isolation, high operation complexity, long construction period and high cost, which are difficult to adapt to the dual needs of precise well section and efficient acidification in strong heterogeneous carbonate rock long horizontal wells. SUMMARY

[0005] The purpose of the present application is to provide a carbonate rock horizontal well acidification optimization method and device to solve the problems of uneven acid distribution, many acidification blind areas and low permeability section reconstruction efficiency in strong heterogeneous carbonate rock horizontal wells in the prior art, and to realize high uniformity acidification of the whole well section and significant improvement of reconstruction effect.

[0006] The above technical purpose of the present application is realized by the following technical scheme: In a first aspect of the present application, a carbonate rock horizontal well acidification optimization method is provided, the method comprising: obtaining a well logging curve of the carbonate rock horizontal well; calculating the equivalent permeability of different well sections according to the well logging curve, and dividing the carbonate rock horizontal well into multiple well sections with similar physical properties according to the pre-configured well section conditions and the equivalent permeability; calculating the buffer distance of the slug of each well section according to the injection flow rate of the acid, the open hole diameter and the desired residence time of the acid and rock reaction, and determining the design length of the slug according to the buffer distance; a diffusion index of the acid liquid in each well section is calculated according to the viscosity of the acid liquid, a local pressure drop gradient of the acid liquid flowing along a channel direction in the reservoir and a local permeability; a coupling relationship among the acid liquid reaction residence time, the tubing moving speed and the well section length is constructed, and the injection rate of the acid liquid injected into the tubing is adjusted according to the coupling relationship; an equal acid injection strategy or a differential acid injection strategy is selected to optimize the acid injection of each horizontal well.

[0007] In an implementation, the well section condition is that a relative change rate of the permeability of adjacent well sections is greater than a permeability mutation threshold, and the length of each well section is greater than a minimum effective well section length.

[0008] In an implementation, the diffusion index is calculated according to the following formula: wherein, viscosity of the acid liquid; a local pressure drop gradient of the acid liquid flowing along a microchannel direction in the reservoir; a local permeability.

[0009] In an implementation, after the diffusion coefficient is calculated, the method further includes: analyzing whether the acid liquid has the ability to turn into a low-permeability area according to the diffusion index, and if the acid liquid has the ability to turn into the low-permeability area, calculating a branch injection flow rate and an action radius of the acid liquid in each well section.

[0010] In an implementation, the coupling relationship is expressed as: wherein, acid liquid reaction residence time; tubing moving speed; well section length.

[0011] In an implementation, the equal acid injection strategy is specifically that the same volume of acid liquid is injected into all well sections. The differential acid injection strategy is specifically that a normalized coefficient of the permeability is determined according to the permeability of each well section, and the volume of the acid liquid injected into each well section is determined according to the normalized coefficient.

[0012] In an implementation, the method further includes: during the injection of the acid liquid into each well section, whether the acidification of each well section is up to the standard is judged according to a change rate of the conductivity of the flowback fluid and a pressure difference change trend before and after the slug; if the acidification is not up to the standard, a reference value of the adjusted slug volume is calculated according to a standard pressure difference response reference value and a measured pressure difference.

[0013] In an implementation, the method further includes: Measuring the maximum injection volume and the minimum injection volume of the acid liquid of each well section, and calculating the injection balance coefficient of each well section according to the maximum injection volume and the minimum injection volume; Measuring the real-time pressure difference during the acid injection process of each well section, calculating the average value of the pressure difference of all well sections according to the real-time pressure difference, and calculating the pressure difference response coordination coefficient of the acidification of each well section according to the real-time pressure difference and the average value.

[0014] In an implementation scheme, the method further comprises: Measuring the flowback fluid response factor, the pressure difference response factor and the productivity response factor of the carbonate rock horizontal well before and after acidification; Weighted summing the flowback fluid response factor, the pressure difference response factor and the productivity response factor to calculate the analysis value of the acidification response; According to the analysis value, the acidification parameters of the similar formation carbonate rock horizontal well or the same carbonate rock horizontal well are optimized.

[0015] The second aspect of the present application provides an electronic device comprising a memory and a processor; The memory is used for storing a computer program, and the computer program comprises program instructions; The processor is used for executing the program instructions to enable the electronic device to perform the steps of the optimization method for carbonate rock horizontal well acidification provided by the first aspect of the present application.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application determines the permeability based on the logging curve, and divides the reconstruction section of the carbonate rock horizontal well; the high-viscosity liquid slug is constructed, the high-viscosity liquid is used to realize the inter-section isolation; the acid liquid is uniformly injected, the viscoelasticity of the acid liquid and the difference in porosity and permeability structure are used to realize the self-adaptive diffusion in the section; the movement of the coiled tubing is controlled to construct the coupling relationship to adjust the acid injection rate and the movement speed; the acid liquid distribution is regulated, the acid liquid parameters are dynamically adjusted in combination with the flowback fluid and the pressure difference response; the whole well section acidification operation is performed, all well sections are processed through the iteration of the slug and the acid injection; the acidification effect is fed back and the acidification parameters are optimized, and the acidification parameters are adjusted based on the flowback fluid and the productivity response. Therefore, it can be seen that the present application constructs a multi-step cooperative acidification regulation mechanism, and is suitable for the uniform acidification treatment of the complex carbonate rock reservoir. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings: Figure 1 A flowchart of an optimization method for carbonate rock horizontal well acidification provided by the embodiments of the present application; Figure 2 A physical well section division schematic diagram provided by the embodiments of the present application; Figure 3 A plug construction schematic provided for an embodiment of the present application; Figure 4 A diverting acid self-adaptive flow schematic provided for an embodiment of the present application; Figure 5 A coiled tubing movement and acid injection rate coupling control schematic provided for an embodiment of the present application; Figure 6 An acid liquid distribution regulation flow chart provided for an embodiment of the present application; Figure 7 An effect feedback and parameter optimization flow chart provided for an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments and drawings, and the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and should not be regarded as a limitation to the present application.

[0019] It should be noted that the term "include" or "may include" used in various embodiments of the present application indicates the existence of the claimed function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their homonyms are only intended to mean a specific feature, number, step, operation, element, component or combination of the foregoing, and should not be understood as first excluding the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing.

[0020] Carbonate reservoirs are one of the important oil and gas hosting media in the world, with multiple percolation channel structures such as fractures, pores and caves. However, such reservoirs usually exhibit obvious heterogeneity, especially in long horizontal wells with a horizontal section length exceeding 1000 meters, the reservoir permeability difference is significant, and phenomena such as rapid breakthrough in high permeability zones and insufficient modification in low permeability sections often occur, which seriously affect the effectiveness and uniformity of acidification modification.

[0021] At present, carbonate reservoir acidification mainly relies on the reaction of acid and rock to generate high conductivity channels to improve the permeability and productivity of the near wellbore zone. However, the traditional acidification process mostly uses a single continuous pumping method, which easily leads to the preferential entry of acid into high permeability channels in strongly heterogeneous reservoirs, resulting in the problem of "non-uniform acidification" such as concentrated acid etching and difficult modification of low permeability regions. In addition, for long horizontal well operations, the acid has a large frictional resistance along the way in the wellbore, and the acid injection front is prone to lose control, further exacerbating the spatial distribution of acidification efficiency.

[0022] In order to improve the acidizing distribution, some existing technologies propose methods such as multi-stage temporary plugging diversion, mechanical well section tool, etc., but there are problems such as unstable plug isolation, high operation complexity, long construction period and high cost, etc., which are difficult to adapt to the dual needs of precise well section and efficient acidizing in carbonate rock strong heterogeneous long horizontal wells.

[0023] Therefore, the present application provides an optimization method for carbonate rock horizontal well acidizing, which adopts the collaborative strategy of "well section plug control + uniform injection of diversion acid + tubing movement regulation + dynamic optimization of parameters" to realize the acidizing reconstruction of long horizontal wells with a horizontal section length of more than 1000 meters.

[0024] It should be understood that the method provided in the embodiment is mainly aimed at the acidizing of long horizontal wells, for example, wells with a length of more than 1000 meters, and of course the acidizing optimization method provided by the present application can also be applied to wells with a length of less than 1000 meters.

[0025] Please refer to Figure 1 , Figure 1 The flowchart of the optimization method for carbonate rock horizontal well acidizing provided by the embodiment of the present application is shown in Figure 1 , which comprises the following steps: S101, obtaining the logging curve of the carbonate rock horizontal well.

[0026] In the embodiment, the original core sample is obtained through logging and core analysis, the pore structure and lithology combination of the reservoir are finely described, and the microscopic structural differences such as fracture development degree and intergranular pore and dissolution pore proportion are mainly identified to build the cognitive basis of reservoir heterogeneity. Conventional logging curves such as natural gamma (GR), acoustic time difference (AC), density (DEN), neutron porosity (CNL) and resistivity (RT) are used.

[0027] S102, calculating the equivalent permeability of different well sections according to the logging curve, and dividing the carbonate rock horizontal well into multiple well sections with similar physical properties according to the pre-configured well section conditions and the equivalent permeability.

[0028] In the embodiment, in view of the problems of significant formation heterogeneity and complex pore and permeability structure in carbonate rock long horizontal wells, the method of multi-source data fusion and physical property feature extraction is used to identify the well section and divide the reconstruction unit of the horizontal section wellbore, which provides the basis for subsequent acidizing parameter matching and injection rhythm control. For example, for carbonate rock long horizontal wells with a horizontal section length of more than 1000 meters, based on logging, logging and core analysis data, the heterogeneity characteristics of the reservoir are identified, the horizontal section is divided into multiple well sections with similar physical properties according to the permeability division range, for example, the permeability division range includes: less than 10 mD, 10-20 mD, 20-50 mD, 50-100 mD and more than 100 mD.

[0029] Based on the logging curve described in step S101, combined with nuclear magnetic resonance (NMR) logging, the effective porosity is obtained. The T2 spectrum distribution is used to identify the ratio of free fluid to bound fluid, and to assist in judging the difference in flow capacity and changes in pore connectivity. The equivalent permeability of different well sections is extracted from the well test analysis data. (mD) is used as the basis for quantitative division of well sections.

[0030] To achieve precise segmentation and differentiated acidizing control, well section modeling was performed based on the identification of formation physical properties and permeability differences. The horizontal section was considered a permeability heterogeneous continuum. Based on the relative permeability change rate of adjacent well sections and the section length criterion, the following well section conditions were adopted: the relative permeability change rate of adjacent well sections was greater than the permeability mutation threshold, and the length of each well section was greater than the minimum effective well section length. The mathematical expression is as follows: ,in, For the Equivalent permeability of each well section (mD); is the permeability mutation threshold (range: 0.3-0.5); For the Length of horizontal well section (m); The minimum effective well section length is set to 20 to 50 (m).

[0031] When the above conditions are met, the adjacent well sections are divided into two independent physical property sections, and the well sections are divided according to the standards in Table 1 below: Table 1

[0032] In order to enhance the mutual calibration capability between porosity and permeability data, the effective porosity and permeability are inverted using the nuclear magnetic resonance logging results. The specific calculation formula is as follows: ,in, is the effective porosity; is the full porosity; is the NMR spectrum area in the free fluid region (T2>33ms); is the total area of ​​the T2 spectrum.

[0033] The Coates model is used to estimate the equivalent permeability, and the calculation formula is as follows: ,in, is the equivalent permeability (mD); is an empirical coefficient, and its value range in carbonate rocks is 0.1 to 100; is the free fluid porosity; is the bound liquid porosity.

[0034] Specifically, W001 well in a certain W work area is selected as a test object. The area has a geological background of strong structure and complex pore superposition, and has the typical characteristics of "strong heterogeneity + long horizontal well structure" targeted by the method of the application. The total length of the horizontal section of the well site target layer is 1850m, the wellbore is designed as a bare hole horizontal section, and the completion method is a casing + windowed open hole structure.

[0035] The reservoir characteristics are as follows: Lithology type: mainly micritic limestone, powdery crystalline limestone, and locally interbedded dolomitic limestone; Pore structure: intergranular pores, dissolution pores, intercrystalline fissures and tectonic fractures are developed; Strong heterogeneity: porosity is 4.2% to 12.5%, permeability is 0.2 to 180mD, and it is distributed in a banded-patchy shape with a sharp spatial variation; Horizontal well trajectory: it passes through multiple different period dissolution zones and fracture zones, and the reservoir physical properties fluctuate frequently along the well section.

[0036] In the two rounds of conventional acidification operations in the well, the 15% HCl full-well continuous acid injection method is used, and the following typical problems exist: (1) Acid liquid preferentially enters the high permeability section, causing insufficient acid liquid coverage in the low permeability section; (2) The response difference between sections is large, and the reaction is uneven; (3) The productivity of multiple sections does not increase, and P2 and P3 sections have no obvious stimulation response.

[0037] These problems are completely consistent with the key problems of long horizontal well heterogeneity acidification reconstruction pointed out by the application, such as "serious flow deviation, inefficient reconstruction, and concentrated acid effect", and can be solved by using the "physical property identification + well section plug + self-adaptive diverting acid + rhythm pushing + response feedback" composite uniform acidification optimization method proposed by the application.

[0038] To solve the problems of "unbalanced acid liquid distribution between sections and insufficient acid effect in low permeability zones" in the acidification reconstruction of W001 well, first, the well section physical property identification and well section division are carried out. Conventional logging + imaging logging (FMI) + nuclear magnetic resonance (NMR) joint analysis is used to identify lithology, pore type and fluid migration capacity.

[0039] Based on the T2 spectrum extracted by nuclear magnetic resonance (NMR), the free fluid zone (T2>33ms) and the bound zone are divided, and the free fluid spectrum area and the total spectrum area are obtained, combined with the measured total porosity , the effective porosity is calculated, and the calculation formula is as follows: wherein, is the effective porosity; is the total porosity.

[0040] For example, the P2 section, the nuclear magnetic resonance logging data shows that the free fluid index FFI = 8.5%, the bound fluid index BVI = 7.2%, according to which the total porosity = 15.7% (total porosity is the sum of the movable and bound fluid volumes in NMR logging), then according to the formula, it is calculated that The result shows that the P2 section has a good acid liquid response basis, and is expected to obtain a more obvious reconstruction gain effect in the subsequent acidizing operation.

[0041] The equivalent permeability is inverted by using the Coates model, from the formula wherein, is the equivalent permeability (mD), is the free fluid porosity; is the bound fluid porosity, is the empirical coefficient. For example, the P5 section, FFI = 13.1%, = 5.6%, the measured = 17.29 mD, the empirical coefficient is inverted by being brought into the formula, thus, in this embodiment, the empirical coefficient C = 3.16 is used for the permeability inversion of other well sections.

[0042] Through calculation, the equivalent permeability of all the 8 physical property well sections is inverted, the error between the inverted value and the value measured in this paper is generally controlled within ± 5%, the maximum is not more than ± 11%, verifying the applicability of the parameters and the reliability of the calculation method.

[0043] In this embodiment, the effective porosity and the equivalent permeability of each well section are calculated according to the mud logging, nuclear magnetic and logging data, the W001 well horizontal section is divided in terms of physical properties in combination with the well depth range, a total of 8 well sections are identified, see Table 2 below: Table 2

[0044] Based on Table 2, the equivalent permeability less than 10 mD is the well section P1, P2 and P3; the equivalent permeability at 10-20 mD is the well section P4 and P5; the equivalent permeability at 20-50 mD is the well section P6 and P7; the equivalent permeability at 50-100 mD is the well section P8. In order to show the permeability difference and the pore structure characteristics of each well section, a physical property well section division schematic diagram is drawn, as shown in Figure 2 Each interval is regarded as an acidification control unit with similar response characteristics, facilitating the parameter linkage matching of the subsequent acid liquid concentration, slug volume, acid injection rate, realizing the coupling control of the acid liquid advancing rhythm and the reservoir liquid absorption capacity.

[0045] S103, according to the injection flow of the acid liquid, the open hole diameter and the expected residence time of the acid liquid and the rock reaction, the buffer distance of the slug of each well section is calculated, and the design length of the slug is determined according to the buffer distance.

[0046] In the embodiment, the slug construction of the high-viscosity liquid of the well section is a key measure to realize the independent acidizing of each well section, and the key point is to form a stable liquid isolation barrier at the starting position of each well section by coiled tubing pump injection of high-viscosity slug liquid, to block the preferential channeling of acid liquid in the high-permeability section, and to ensure that the acid liquid fully acts in the target well section.

[0047] The slug arrangement is combined with the well section result divided in step S102, and factors such as the starting point of the well section, the position of the permeability mutation of the formation and the acidizing response sensitivity are preferentially considered, and the slug volume and the slug liquid viscosity need to match the wellbore size and the operation pump pressure condition. The slug liquid can use but is not limited to guar gum high molecular liquid system, and forms a stable suspended colloid, and the design viscosity range is: wherein, is the viscosity of the slug liquid (mPa·s), and the viscosity value needs to consider the construction temperature (60-90°C), the formation pressure (25-45MPa) and the shear environment of the wellbore.

[0048] The slug arrangement point needs to be close to the starting position of each well section, and is preferentially set at the front of the permeability mutation, so as to block the invalid channeling of the acid liquid in the high-permeability channel. In order to prevent the channeling interference between the slug liquids of adjacent well sections, the minimum safe buffer distance needs to be calculated according to the acid injection flow, the wellbore diameter and the target reaction residence time, and the slug design length is determined on this basis. In order to avoid the crosstalk of multiple slug liquids, the buffer distance of the slug can be calculated, and the formula is: wherein, is the buffer distance (m) between the front edge of the slug and the acid section; is the subsequent acid injection flow; is the designed reaction residence time (min).

[0049] The design length of the slug is determined according to the buffer distance of the slug of each well section, and the total pump volume of the slug liquid can be estimated according to the wellbore size and the well section length, and the formula is as follows: wherein, is the single-section slug volume; is the wellbore inner diameter (m); is the design length of the slug liquid column, which is generally designed to be 3-8m.

[0050] Exemplary, after the completion of the full well section physical property identification and 8 section reconstruction unit division, in order to realize the physical isolation of acid liquid between different permeability sections and limit the inter-section channeling, the high viscosity plug liquid + coiled tubing pushing method proposed in the application is used to construct the plug barrier, so as to ensure the independent reaction environment of acid liquid in each section.

[0051] The plug liquid formula selects a downhole high temperature shear resistant high molecular crosslinking plug system, which is composed of: main crosslinking group: modified hydroxypropyl guar gum (1.5%); bonding enhancer: polyacrylamide (0.3%); crosslinking agent: slow-release borate (0.15%); fluid loss additive: micro-particle plugging agent (0.05%); temperature adaptability: ≤160℃; viscosity actually measured: ≥200 mPa·s (100℃, 170s -1 ). The system can achieve effective inter-section plugging ≥20 min in the high permeability fracture section without obvious leakage.

[0052] The plug volume is calculated by the formula , wherein, is the open hole diameter, which is measured on site as 0.165 m; is the plug liquid column design length, which is divided into 3-8 m according to the liquid absorption capacity of the physical section. Considering the reservoir liquid absorption fluctuation, a safety compensation coefficient is added to adjust the plug volume, and the calculation formula becomes .

[0053] Taking P5 section as an example, the plug length is designed as , the wellbore inner diameter is ; by calculation , considering the liquid absorption compensation, the final plug volume is calculated as .

[0054] In order to ensure the stability of on-site construction, the final volume of each plug liquid is set as shown in the following table 3: Table 3

[0055] The plug liquid injection is completed by coiled tubing, and the well section is constructed in reverse order from the wellbore bottom to the wellhead direction in priority, so as to ensure the liquid gravity stability and the integrity of the lower plug. After the injection of each plug, a short time of standing should be carried out to ensure that the plug liquid forms a homogeneous section in the wellbore without stratification or collapse. As can be seen from the above table, P8 section is a high permeability section, and a double plug parallel sealing structure (15 m between the front and rear plug liquids) is used on site to ensure that the acid liquid does not channel to the high absorption section. Please refer to Figure 3 for the plug integrity and isolation verification. In the process of on-site construction, the micro-flowback pressure test method is used to detect the plug barrier effect: the flowback section pressure difference: ΔP is greater than or equal to 2.5 MPa; the flowback liquid conductivity does not decrease significantly; the residence time is greater than or equal to 25 min, and there is no obvious plug leakage.

[0056] The embodiment proposes a new mechanism of well section fine acidification for strong heterogeneous carbonate reservoirs, and realizes acid liquid physical isolation control through high viscosity plug construction, so as to ensure the independence and uniformity of each well section in the acidification process.

[0057] In S104, the diffusion index of the acid liquid of each well section is calculated according to the viscosity of the acid liquid, the local pressure drop gradient of the acid liquid flowing in the channel direction in the reservoir, and the local permeability.

[0058] In the embodiment, the acid liquid is a diverting acid liquid with self-diverting capability, and the diverting acid with self-diverting capability is injected in each physical well section. By using the viscoelasticity and rheological properties of the acid liquid, in combination with the difference in reservoir porosity and permeability structure, the self-adaptive flow and uniform distribution of the acid liquid in the section are realized, and the reconstruction effect of the low permeability area is enhanced.

[0059] The diverting acid liquid is a composite system composed of viscoelastic thickening agent, surfactant and retardation reagent. For example, the main acid agent is hydrochloric acid (HCL) with a concentration of 10-28%, which has the ability to increase viscosity and maintain structure with pH value, and is preferably suitable for reservoir well sections with permeability less than 50 mD. In the formation with low porosity and weak flow capacity, the self-diversion and uniform diffusion of the acid liquid can be realized, and the acidification production degree of the low permeability area is effectively improved.

[0060] After the acid liquid is injected into the target well section, its diverting and diffusing capability is mainly controlled by the viscosity of the acid liquid, the micro pressure difference and the local permeability, and its diverting trend can be evaluated by the diverting diffusion index, and the calculation formula is as follows: Wherein, is the diffusion index of the acid liquid diversion, which is used to quantitatively represent whether the acid liquid has the ability to divert into the low permeability area; is the viscosity of the acid liquid (mPa·s); is the local pressure drop gradient of the acid liquid in the micro channel direction in the reservoir (MPa / m); is the local permeability (mD).

[0061] As a specific embodiment, the embodiment controls to ensure that the acid liquid has effective self-diverting capability and avoids concentrated acid erosion caused by flowing only in high permeability channels.

[0062] When the diffusion coefficient is greater than 1.0, in order to further improve the distribution balance of the acid liquid in the well section, a dynamic branch injection regulation model based on the flow factor is used, and the formula is as follows: Wherein, is the acid liquid flow rate injected into the first branch; is the total acid injection flow rate of the section; is the relative flow factor of the first branch. Total number of micro-paths that acid can enter in this interval.

[0063] Based on the fluid propulsion theory, the effective range of acid in the reservoir can be estimated, the formula is as follows: Wherein, is the effective radius of acid (m); is the average permeability of this interval (mD); is the effective reaction residence time of acid in this interval (min); is the formation porosity (dimensionless); is the viscosity of acid (mPa·s).

[0064] For the purpose of W001 well in W work area, carbonate rock pore and fracture development degree and liquid absorption heterogeneity, the following composite diverting acid system is selected, as shown in the following table 4: Table 4

[0065] In order to evaluate whether the acid can effectively enter the low permeability channel, the formula is as follows: Wherein, is the viscosity of acid (mPa·s); is the local pressure drop gradient (MPa / m); is the permeability of this interval (mD). Taking P2 interval as an example, , , , it is calculated that . This value indicates that the acid has certain diverting diffusion capacity, which can offset the flow path to enter the area with finer pore throat and lower permeability. Please refer to Figure 4 , the self-adaptive flow diagram of diverting acid.

[0066] In order to further control the distribution of acid in the interval, a dynamic injection model based on flow resistance factor is constructed: Wherein, is the acid flow rate injected into the first branch; is the total acid injection flow rate of this interval; is the relative flow resistance factor of the first branch; is the total number of micro-paths that acid can enter in this interval. Taking P5 interval as an example, assuming that there are 3 micro-channels, the flow resistance factors are , the total acid injection rate , then , , which indicates that the acid liquid actively enters the channel with smaller resistance, and the engineering realizes the predictable and controllable distribution balance in the section. By adjusting the injection proportion of different branches, the acid liquid can be moderately deviated to the path with weak liquid absorption capacity, so as to improve the uneven phenomenon of acid liquid distribution.

[0067] Based on the fluid propulsion theory, the action radius of the acid liquid in a certain well section is calculated by the formula , wherein, is the action radius of the acid liquid (m); is the average permeability of the well section (mD); is the effective reaction residence time of the acid liquid in the section (min); is the formation porosity (dimensionless); is the viscosity of the acid liquid (mPa·s). Taking the P3 section as an example, , , , , the result is calculated as , which indicates that the acid liquid can effectively cover the main porosity and permeability area in this section, which is greater than the designed target propulsion depth (5 m). Considering the heterogeneity and diffusion resistance of the carbonate rock section, the radius has a good reconstruction range. In the subsequent steps, the means such as increasing the residence time or adjusting the acid liquid viscosity can be combined to realize the optimization of the response type propulsion distance.

[0068] After each section acidizing, the uniformity and acid response are immediately judged by the following means: the pH and Fe 2+ peak value of the flowback liquid judges the acid corrosion activity; the well section differential pressure ΔP is monitored in real time, and ΔP<1.5 MPa indicates that the reaction is insufficient; whether the conductivity curve is a single peak decay type, if the fluctuation is violent, there may be a slug penetration or acid liquid deviation. If the feedback is not up to standard, adjust in the next section: for example, increase the acid liquid concentration from 18% to 20%; increase the acid injection rate by 10%, and increase the slug volume to ≥0.18 m 3 .

[0069] It can be seen that the embodiment adopts the diverting acid system with viscoelasticity and self-diverting capability, combines the porosity and permeability structure difference and the acid liquid distribution mechanism in the section, and significantly improves the acid corrosion coverage and acid liquid utilization efficiency in the low permeability section.

[0070] S105, a coupling relationship between the acid liquid reaction residence time, the tubing moving speed and the well section length is constructed, and the injection rate of the tubing for injecting the acid liquid is adjusted according to the coupling relationship, In the embodiment, the movement control of the coiled tubing is to accurately control the contact time and diffusion path of the acid liquid between the wellbore and the reservoir through the coupling control mode of speed control propulsion and quantitative injection in the carbonate rock long horizontal well acidizing operation, and to ensure the uniformity of the acid liquid reaction and the sufficiency of the acid corrosion in each well section.

[0071] The present application establishes a coupling relationship between the acid liquid reaction residence time and the tubing movement speed , the length of the well section , and the expression of the coupling relationship is: , wherein, is determined by step S102.

[0072] The embodiment introduces a coupling control model of the coiled tubing movement speed and the acid injection rate, dynamically controls the acid liquid propulsion path and the reaction residence time, and realizes the adjustable and predictable acid etching process.

[0073] According to the characteristics of the large variation of the liquid absorption capacity of the carbonate reservoir and the strong heterogeneity, the movement speed and the acid injection rate need to be positively coupled and adjusted with the local liquid absorption capacity of the reservoir to dynamically adapt to the formation response conditions of different sections.

[0074] In the actual construction process, the movement speed of the coiled tubing is controlled in the range of 0.5-3.0 m / min, the acid injection rate is controlled in the range of 0.3-1.5, and the acidification real-time monitoring system is used to dynamically feedback the formation liquid absorption rate and the change of the flowback pressure, so as to adjust to ensure the reaction balance in the target range.

[0075] In order to realize the quantitative injection, stable propulsion and reaction balance of the acid liquid in the carbonate rock long horizontal well acidification operation process, the coupling control mechanism of “speed control propulsion and quantitative injection” is adopted in this step to accurately control the contact time and diffusion path of the acid liquid between the wellbore and the reservoir, and to ensure the uniformity of the acid liquid reaction and the sufficiency of the acid etching effect in different physical property well sections.

[0076] Please refer to Figure 5 , and realize the coupling control of the tubing movement and the acid injection rate by combining the coupling relationship provided in the embodiment.

[0077] Taking the P3 section as an example, the permeability is 7.11 mD (medium-low permeability layer), the length of the section is , the initial setting of the coiled tubing propulsion speed is , and the acid liquid reaction residence time is calculated by substituting the formula as According to the result, the acid liquid reaction residence time of this section is higher than the recommended control range (20-40 min) of the present application, and there is a risk of “slow propulsion”, so the construction parameters need to be adjusted.

[0078] If the movement speed of the tubing is adjusted to , and the original acid injection displacement is maintained, then the calculation is as follows: , which meets the target range. The field can appropriately speed up the adjustment speed according to the feedback of the formation liquid absorption capacity, and the flowback liquid pH and ΔP recovery curves are normal, which verifies the effective control.

[0079] The acidizing construction of this well section adopts the on-site monitoring system: surface acid injection parameters ( 、 ) Online adjustment; downhole pressure sensor real-time feedback ΔP; return fluid conductivity and Fe 2+ Concentration determines whether the reaction is sufficient; on-site The calculation results form the recommended construction parameters as shown in Table 5 below: Table 5

[0080] S106, selecting an equal amount of acid injection strategy or a differential acid injection strategy to optimize the acid injection of each horizontal well.

[0081] In this example, acid distribution control is the core regulatory mechanism for achieving balanced acidizing across the entire section of a long horizontal carbonate well. The acid distribution strategy selects either equal or differential acid injection based on the permeability and lithologic sensitivity of each well section. In combination with conductivity trends of short-cycle flowback fluid and acid consumption analysis, the injection system parameters are adjusted in real time to accommodate differences in fluid absorption capacity and reaction conditions between sections.

[0082] First, in the operation design stage, the equivalent permeability of each well section obtained in step S102 is , preferably adopt one of the following two strategies: Equal volume acid injection strategy: Applicable to the same section of medium permeability to high permeability or similar reservoir sections, setting the same acid injection volume in all well sections , the formula is: .

[0083] Differential acid injection strategy: Applicable to situations where the permeability spans significantly. The acid volume is allocated according to the permeability normalization coefficient. The formula is as follows: ,in, For the Volume of acid injected into the segment; The total designed volume of acid fluid for the entire well section; is the equivalent permeability of a well section (mD); The principle of acid distribution is that the permeability value increases from small to large, and the corresponding acid volume increases from large to small.

[0084] This strategy ensures that the acid is "differentiatedly distributed" according to the differences in the fluid absorption capacity of the well sections, avoiding phenomena such as over-acidification in high-permeability sections and under-acidification in low-permeability sections.

[0085] During the acid injection process, combined with the coiled tubing position and acid injection parameters, short-cycle flowback analysis and inter-stage pressure differential response monitoring are implemented to determine whether the acidizing process in the current section meets the standards. The following two types of indicators are used for regulation: (1) The change rate of conductivity of flowback fluid (%): used for judging the reaction degree of acid liquid; (2) The change trend of pressure difference (ΔP) before and after the slug: used for judging the acid liquid propulsion integrity.

[0086] When the change trend of conductivity of flowback fluid is detected to be slow or the pressure difference fluctuation is abnormal, the parameter adjustment logic is automatically triggered. The adjustment mechanism can adopt the following formula: , wherein, is the reference value of slug volume adjustment; is the standard pressure difference response reference value (MPa); is the measured pressure difference (MPa); is the response coefficient (generally 0.8-1.2).

[0087] Based on the above judgment result, the subsequent acid liquid concentration, injection rate or slug length can be dynamically adjusted. For example, if the pressure difference fluctuation is large, the slug volume is increased to prevent acid liquid channeling; if the conductivity rises with a lag, the acid liquid concentration is increased or the residence time is prolonged.

[0088] Please refer to Figure 6 , the acid liquid distribution control flowchart. In the embodiment, the permeability of each well section determined in step S102 is combined with the lithology sensitivity to select two types of strategies, equal acid injection and differential acid injection, and the acid liquid volume of the well section is designed.

[0089] In the actual injection process, the injection concentration, injection rate and slug volume are dynamically adjusted in real time in combination with the short-period flowback fluid analysis and the pressure difference response monitoring result to adapt to the inter-zone liquid absorption capacity and acid etching reaction condition difference.

[0090] The well permeability difference is obvious (from 1.36 mD to 58.23 mD). According to the recommendation of the application, the differential acid injection strategy is adopted, the known data in step S101 are combined, =160.13, the designed acid injection volume of the whole well section is: . The calculation formula of the differential acid injection strategy is calculated by taking P1 section as an example, , the acid injection volumes of P1-P8 sections are 148.1 , 99.7 , 63.2 , 44.0 , 27.2 , 18.1 , 11.2 , 3.5 .

[0091] In the acid liquid injection process, the change rate of conductivity of short-period flowback fluid and the change , to determine whether to trigger dynamic parameter adjustment. The differential pressure response control formula is , wherein, is the reference value of the slug volume adjustment (m 3 ); is the standard differential pressure response reference value (MPa); is the measured differential pressure (MPa); is the response coefficient (1.0 for this well). Taking the P6 section as an example, the measured differential pressure , and thus is calculated. According to the result, in the next section (P7), the slug volume needs to be increased by 0.7 m 3 , in order to raise the front differential pressure and improve the acid liquid propulsion balance.

[0092] In actual construction process, if the conductivity change rate is lower than 5% and the acid consumption does not reach the threshold value, the acid concentration is increased to 20%; if the differential pressure is abnormal or fluctuates obviously, the slug volume is increased or the propulsion speed is reduced; if the acid consumption is high or the flowback lags, the residence time is extended or the dilute system is switched.

[0093] In some embodiments, the method further comprises: measuring the maximum injection volume and the minimum injection volume of the acid liquid for each section, calculating the injection balance coefficient of each section according to the maximum injection volume and the minimum injection volume; measuring the real-time differential pressure during the acid injection process of each section, calculating the average value of the differential pressure of all sections according to the real-time differential pressure, and calculating the differential pressure response coordination coefficient of each section acidification according to the real-time differential pressure and the average value.

[0094] Specifically, the full-section acidification operation is performed on the basis of completing section identification, slug construction, acid injection parameter design, and acid injection response regulation, and implementing the inter-section acidification circulation construction process throughout the entire horizontal section, so as to ensure that the carbonate long horizontal well realizes uniform acid coverage and efficient use under the condition of heterogeneous reservoir. The core of the present embodiment is a composite acidification mode combining "section slug construction + diversion acid injection + coiled tubing movement + response regulation", which adopts a construction mechanism of inter-section propulsion, parameter linkage, and rhythm control, and develops the acidification operation from the distal end to the proximal end of the wellbore section by section, so as to ensure that the acid etching reaction covers no omission and the response effect is coordinated and unified.

[0095] To realize the uniformity control of the full-section acid liquid injection distribution, the acid liquid inter-section injection balance coefficient is introduced, and the expression is: , wherein, is the injection balance coefficient of the acid injection volume; is the acid injection volume of the i th section; is the total number of well sections. When , it indicates that the inter-section acid liquid injection amount is balanced, which is beneficial to realize the consistency of acid liquid propulsion. Conversely, if If it is too large, it means that the acid distribution between sections is quite different and the acid injection strategy needs to be adjusted.

[0096] At the same time, in order to evaluate the synchronization and coordination of the acidizing reaction process in each well section, the acidizing response coordination coefficient is introduced, and the expression is: ,in, is the coordination coefficient of pressure difference response; For the Real-time pressure difference during acid injection (MPa); is the average pressure difference of all well sections (MPa); The pressure difference response coordination coefficient is used to determine the degree of difference in the propulsion resistance of the acid fluid in different well sections. The higher the coordination, the more uniform the acid fluid response process and the smaller the difference between sections.

[0097] For example, during construction, Less than 0.3MPa to control the risk of acidification imbalance.

[0098] This embodiment adopts a reverse construction sequence from the farthest end of the wellbore to the near wellhead, completing the following operations in sequence: High-viscosity liquid is pumped into the coiled tubing to construct an isolation slug at the top of the current section, with a controlled thickness of 3.5 to 5.0 m; Inject a predefined diverting acid system with a displacement of 0.4–0.8 and a tubing velocity of 2.5–4.0 m / min; After each injection, the injection was allowed to stand for 3–5 minutes, and the flowback fluid was collected and a dual-parameter diagnosis of conductivity and differential pressure was performed; According to the feedback, the acid injection concentration, residence time or slug volume of the next section can be adjusted in real time; The acid injection cycle from well section P1 to well section P8 was completed in sequence, and the total construction process took 21 hours.

[0099] The balance coefficient of acid volume distribution is used to evaluate the balance of the entire acid injection process. ,in, is the acid injection volume distribution balance coefficient; For the Acid injection volume for each well section; is the total number of well sections in the whole well. Based on the above differential acid injection design P1=148.1, P8=3.5, it is calculated that , as can be seen from the results, the value is too large. The reason is that the "strong differential acid injection strategy" is adopted to strengthen the acid etching of the low permeability section. According to the flowback data, the acid effect distribution is basically balanced, indicating that the strategy is reasonable. However, if it is changed to a mixed method of "differential + rebalancing within the section", it can be further reduced. To below 10.0. Reaction coordination evaluation formula , calculate the pressure difference data 0.34MPa, which shows that the coordination is close to the control threshold (0.3MPa). In subsequent construction, it is recommended to increase the acid residence time or use a stronger retarder to control the reaction synchronization. It reaches 42.3, indicating that the difference in acid injection amount between stages is large, matching the strong heterogeneous structure; but The value is 0.34 MPa, close to the critical value, indicating that the inter-stage propulsion pressure is not yet fully coordinated. It is recommended that these two indicators be further combined in actual projects to adjust the slug volume and acid injection rhythm to achieve dual optimization of acid distribution and reaction synchronization.

[0100] In some embodiments, the existing technology for evaluating the acidizing effect of horizontal wells generally only considers the impact of productivity, which leads to inaccurate analysis of the acidizing effect. Therefore, the method provided in this embodiment also includes: measuring the return fluid response factor, pressure difference response factor and productivity response factor of the carbonate horizontal well before and after acidizing; performing weighted summation of the return fluid response factor, pressure difference response factor and productivity response factor to calculate the analysis value of the acidizing response; and optimizing the acidizing parameters of carbonate horizontal wells in similar formations or the same carbonate horizontal wells based on the analysis value.

[0101] Specifically, after completing the acidizing operation of the entire well section, this embodiment comprehensively evaluates the actual acidizing effect of each physical property well section through return fluid detection, pressure difference change analysis, and production capacity response evaluation. Based on this, the acid parameter configuration, slug design, and acid injection control strategy are optimized to establish an acidizing closed-loop control and rolling improvement mechanism.

[0102] See also Figure 7 The analysis of acidification effect is mainly carried out from the following three dimensions: (1) Flowback fluid indicators: including pH value of flowback fluid, Ca 2+ Concentration, conductivity, etc. are used to determine the reaction intensity and the degree of karst dissolution; (2) Pressure differential response characteristics: Through multi-point pressure measurement, the pressure differential change amplitude ΔP before and after acidization is analyzed to evaluate the acid propulsion effect and slug integrity; (3) Productivity improvement: The effect of acidizing transformation is determined by comparing parameters such as single-stage liquid production, test flow pressure, oil-gas-water ratio, etc. before and after acidizing.

[0103] In order to achieve quantitative evaluation, the present invention constructs an analysis function of acidification response, and the formula is as follows: ,in, For the A comprehensive score of the acidization response of each well section (0–1, with higher values ​​indicating better stimulation effects); is the capacity response factor, which is calculated by normalizing the output increase; is the flowback fluid response factor, based on pH, Ca 2+ variation amount construction; is the differential pressure response factor, reflecting the differential pressure change amplitude before and after the plug; is the weight coefficient of the corresponding factor, and the values are 0.5, 0.3 and 0.2 respectively.

[0104] The embodiment establishes a feedback control mechanism based on the conductivity, pH value and differential pressure response of the flowback fluid, and can realize real-time optimization and response closed loop of parameters during construction.

[0105] According to the analysis results calculated by the function, the subsequent parameter optimization of similar formations or subsequent acidification stages of the same well section is carried out, including but not limited to: If , it means that the acidification effect is weak, and it is recommended to increase the acid concentration or appropriately prolong the residence time; If is significantly low, it indicates that the plug stability is insufficient or the acid liquid channeling risk is high, and it is recommended to increase the plug volume or adjust the interval; If is high, and is significantly low, it means that the acid has reacted fully, and a low-cost weak acid replacement system can be selected subsequently.

[0106] Further, by summarizing the acidification effect and response parameters of different well sections, an acidification parameter database based on the response characteristics of well sections can be gradually established, which is used to support the acidification parameter design reference and construction experience review under similar reservoir conditions, and enhance the adaptability and reuse value of the method.

[0107] Exemplarily, the well section data analysis (part) of S7 well is shown in Table 6 as follows: Table 6

[0108] From Table 6 above, parameter optimization can be carried out through feedback analysis: If (such as P8), increase the acid concentration to 20%, or reduce the pushing rate and prolong the reaction time.

[0109] If is low (such as P8), increase the plug volume or use double plug isolation technology to raise the acid front differential pressure.

[0110] If is high, and is low (such as P5), consider using a weak acid system or a slow reaction combination in the subsequent stage to improve the reaction efficiency and economy.

[0111] In combination with the above described embodiments, the specific execution process of the well section acidification operation of the present application is as follows: (1) According to the divided well sections, the reverse construction method is adopted, that is, starting from the end section of the wellbore and advancing towards the wellhead in sequence; (2) In each well section, high-viscosity plug injection and positioning are first implemented to establish a liquid isolation barrier between sections; (3) Then, the acid is uniformly injected, and the acid ratio, concentration, injection rate and coiled tubing movement speed are carried out according to the set parameters; (4) After the acid injection is completed, enter the short-term static or micro-flowback stage, and monitor the slug stability and the change trend of the flowback fluid conductivity in real time; (5) If the conductivity of the return fluid, acid consumption changes, or the pressure difference between stages responds abnormally, the parameters of the next stage of acid injection will be adjusted according to the dynamic control mechanism; (6) Repeat the construction of the segment plug, acid injection and movement control in each well section until all sections of the well are covered, realizing the acidizing operation between sections with continuous advancement from far to near and feedback closed loop.

[0112] During the operation, a wellbore advancement rhythm model and segment acid injection execution sequence are established by combining the real-time coiled tubing depth identification system, the downhole pressure change monitoring system, and the surface acid control interface. This rhythm model includes key variables such as the construction time of each segment, the delay between segment switching, and the return flow judgment time window, which are used to control the acid advancement rhythm and match the operation window. It is preferred to conduct a staged return flow analysis and surface pressure curve analysis after completing every two well sections to evaluate the integrity of the slug, the uniformity of the acid distribution, and the operation accuracy, thereby ensuring the continuity, stability, and complete coverage of the acidizing process.

[0113] An embodiment of the present invention further provides an electronic device. The electronic device includes a processor, a memory, a communication interface, and at least one communication bus for connecting the processor, the memory, and the communication interface. The memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (PROM), or a compact disc read-only memory (CD-ROM), and is used to store relevant instructions and data.

[0114] The communication interface is configured to receive and send data. The processor can be one or more CPUs, and in the case of one CPU, the CPU can be a single-core CPU or a multi-core CPU. The processor in the electronic device is configured to read one or more programs stored in the memory and perform the following operations: obtaining a well logging curve of the carbonate rock horizontal well; calculating equivalent permeability of different well sections according to the well logging curve; dividing the carbonate rock horizontal well into multiple well sections with similar physical properties according to pre-configured well section conditions and in combination with the equivalent permeability; calculating a buffer distance of a slug of each well section according to an injection flow rate of the acid liquid, a bare hole diameter and an expected residence time of the acid liquid and the rock; determining a design length of the slug according to the buffer distance; calculating a diffusion index of the acid liquid of each well section according to a viscosity of the acid liquid, a local pressure drop gradient and a local permeability of the acid liquid flowing in a channel direction in the reservoir; constructing a coupling relationship among the acid liquid reaction residence time, the tubing moving speed, the acid injection rate and the length of the well section, and adjusting the acid injection rate of the tubing according to the coupling relationship; and selecting an equal acid injection strategy or a differential acid injection strategy to optimize the acid injection of each horizontal well section.

[0115] It should be noted that the specific implementation of each operation can be described above with respect to the method embodiments Figure 1 It should be noted that the specific implementation of each operation can be described above with respect to the method embodiments

[0116] The embodiment of the present application further provides a computer readable storage medium, which is a memory device in a computer device and is used for storing programs and data. It can be understood that the computer readable storage medium herein can include an internal storage medium in the computer device, and of course can include an extended storage medium supported by the computer device. The computer readable storage medium provides a storage space, which stores an operating system of the terminal. Furthermore, one or more instructions suitable for being loaded and executed by the processor are stored in the storage space, and the instructions can be one or more computer programs (including program codes). It should be noted that the computer readable storage medium herein can be a high-speed RAM memory or a non-volatile memory, for example, at least one disk memory. The one or more instructions stored in the computer readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the above-mentioned embodiment of the carbonate rock horizontal well acidification optimization method. It should be understood by those skilled in the art that the embodiment of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0117] The embodiment of the present application further provides a computer program product containing program instructions. The computer program product can be a software or program product containing program instructions, which can be run on a computing device or stored in any available medium. When the computer program product is run on at least one electronic device, the at least one electronic device is caused to perform the carbonate rock horizontal well acidification optimization method.

[0118] The above detailed description further explains the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above detailed description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for optimizing the acidizing of carbonate horizontal wells, characterized in that: include: Obtaining well logging curves for carbonate horizontal wells; The equivalent permeability of different well sections is calculated based on the well logging curve. Based on the pre-configured well section conditions and the equivalent permeability, the carbonate horizontal well is divided into multiple sections with similar physical properties. The buffer distance of the slug in each well section is calculated based on the acid injection rate, the open hole diameter, and the expected residence time of the acid and rock reaction. The design length of the slug is determined based on the buffer distance. The diffusion index of the acid fluid in each well section is calculated based on the viscosity of the acid fluid, the local pressure drop gradient of the acid fluid flowing along the channel direction in the reservoir, and the local permeability; Establish a coupling relationship between the acid reaction residence time, tubing movement speed, and well section length, and adjust the injection rate of the acid into the tubing based on the coupling relationship; The equal amount acid injection strategy or differential acid injection strategy is selected to optimize the acid injection of each horizontal well.

2. The optimization method for acidizing a carbonate horizontal well according to claim 1, characterized in that: The well section condition is specifically: the relative permeability change rate of adjacent well sections is greater than the permeability mutation threshold, and the length of each well section is greater than the minimum effective well section length.

3. The optimization method for acidizing a carbonate horizontal well according to claim 1, characterized in that: The calculation formula of the diffusion index is: ,in, is the viscosity of the acid; is the local pressure drop gradient of the acid fluid in the reservoir along the microchannel direction; is the local permeability.

4. The optimization method for acidizing a carbonate horizontal well according to claim 3, characterized in that: After calculating the diffusion coefficient, the method further includes: analyzing whether the acid fluid has the ability to turn into the low permeability area based on the diffusion index; if the acid fluid has the ability to turn into the low permeability area, calculating the injection flow rate and effective radius of the acid fluid in each well section.

5. The optimization method for acidizing a carbonate horizontal well according to claim 1, characterized in that: The expression of the coupling relationship is: ,in, is the residence time of acid reaction; is the moving speed of the oil pipe; is the well section length.

6. The optimization method for acidizing a carbonate horizontal well according to claim 1, characterized in that: The equal volume acid injection strategy specifically includes: injecting the same volume of acid in all well sections; The differential acid injection strategy specifically includes: determining a normalized coefficient of permeability according to the permeability of each well section, and determining the volume of acid injected into each well section according to the normalized coefficient.

7. The method for optimizing carbonate horizontal well acidizing according to claim 1, characterized in that: The method further comprises: During the acid injection process in each well section, the conductivity change rate of the flowback fluid and the pressure difference before and after the plug are used to determine whether the acidification of each well section meets the standards. If the acidification does not meet the standards, the reference value for adjusting the slug volume is calculated based on the standard pressure difference response reference value and the measured pressure difference.

8. The method for optimizing carbonate horizontal well acidizing according to claim 1, characterized in that: The method further comprises: Measure the maximum and minimum injection volumes of acid fluid in each well section, and calculate the injection balance coefficient of each well section based on the maximum and minimum injection volumes; The real-time differential pressure during acid injection in each well section is measured, and the average differential pressure of all well sections is calculated based on the real-time differential pressure. The differential pressure response coordination coefficient of acidization in each well section is calculated based on the real-time differential pressure and the average value.

9. The method for optimizing carbonate horizontal well acidizing according to claim 1, characterized in that: The method further comprises: Measure the flowback response factor, differential pressure response factor, and productivity response factor of carbonate horizontal wells before and after acidizing; The flowback response factor, differential pressure response factor and productivity response factor are weighted and summed to calculate the analytical value of the acidification response; Based on the analysis values, the acidizing parameters of carbonate horizontal wells in similar formations or horizontal wells in the same carbonate formation are optimized.

10. An electronic device, characterized in that: including memory and processor; a memory for storing a computer program, wherein the computer program includes program instructions; The processor is configured to execute the program instructions so that the electronic device performs the steps of the method for optimizing acidizing of carbonate horizontal wells according to any one of claims 1 to 9.

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