An optimization method and apparatus for carbonate horizontal well acidizing

Abstract

The application discloses a carbonate rock horizontal well acidification optimization method and equipment, relates to the technical field of oil and gas field stimulation and reconstruction, and has the technical scheme as follows: according to pre-configured well section conditions, carbonate rock horizontal wells are divided into multiple well sections with similar physical properties in combination with equivalent permeability; according to the injection flow rate of acid liquid, the open hole diameter and the expected residence time of acid liquid and rock reaction, the buffer distance of each well section is calculated, and the design length of the slug is determined according to the buffer distance; according to the viscosity of acid liquid, the local pressure drop gradient and the local permeability of acid liquid flowing in the channel direction in the reservoir, the diffusion index of acid liquid of each well section is calculated; the 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 tubing for injecting acid liquid is adjusted according to the coupling relationship; and the equal acid injection strategy or the differential acid injection strategy is selected to optimize the acid liquid injection of each 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 area. However, the traditional acidification process mostly uses 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 frictional resistance along the way in the wellbore, and the acid front is prone 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 acidification 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:

[0007] In a first aspect of the present application, a carbonate rock horizontal well acidification optimization method is provided, the method comprising:

[0008] obtaining a well logging curve of the carbonate rock horizontal well;

[0009] 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;

[0010] According to the injection flow rate of the acid liquid, the open hole diameter and the expected residence time of the acid liquid and the rock, a 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;

[0011] 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, a diffusion index of the acid liquid of each well section is calculated;

[0012] 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;

[0013] An equal acid injection strategy or a differential acid injection strategy is selected to optimize the acid liquid injection of each horizontal well.

[0014] In an implementation scheme, the well section condition is that the 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.

[0015] In an implementation scheme, the calculation formula of the diffusion index is: wherein, viscosity of the acid liquid; local pressure drop gradient of the acid liquid flowing in the microchannel direction in the reservoir; local permeability.

[0016] In an implementation scheme, after the diffusion coefficient is calculated, the method further includes: analyzing whether the acid liquid has the ability to turn into the low-permeability area according to the diffusion index, and if the acid liquid has the ability to turn into the low-permeability area, calculating the branch injection flow rate and the action radius of the acid liquid in each well section.

[0017] In an implementation scheme, the expression of the coupling relationship is: wherein, acid liquid reaction residence time; tubing moving speed; well section length.

[0018] In an implementation scheme, the equal acid injection strategy is specifically that the same volume of acid liquid is injected in all well sections.

[0019] 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.

[0020] In an implementation scheme, the method further includes:

[0021] During the acid injection of each well section, whether the acidification of each well section is up to the standard is judged according to the conductivity change rate of the flowback fluid and the pressure difference change trend before and after the slug;

[0022] If the acidification is not up to the standard, the reference value of the adjusted slug volume is calculated according to the standard pressure difference response reference value and the measured pressure difference.

[0023] In an implementation scheme, the method further comprises:

[0024] The maximum injection volume and the minimum injection volume of the acid liquid of each well section are measured, and the injection balance coefficient of each well section is calculated according to the maximum injection volume and the minimum injection volume.

[0025] The real-time pressure difference during the acid injection of each well section is measured, the average value of the pressure differences of all well sections is calculated according to the real-time pressure difference, and the pressure difference response coordination coefficient of the acidification of each well section is calculated according to the real-time pressure difference and the average value.

[0026] In an implementation scheme, the method further comprises:

[0027] The flowback fluid response factor, the pressure difference response factor and the productivity response factor of the carbonate rock horizontal well before and after the acidification are measured;

[0028] The flowback fluid response factor, the pressure difference response factor and the productivity response factor are weighted and summed to calculate the analysis value of the acidification response;

[0029] The acidification parameters of the carbonate rock horizontal well of similar formation or the same carbonate rock horizontal well are optimized according to the analysis value.

[0030] The second aspect of the present application provides an electronic device comprising a memory and a processor;

[0031] The memory is used for storing a computer program, and the computer program comprises program instructions;

[0032] The processor is used for executing the program instructions to enable the electronic device to perform the steps of the optimization method of the carbonate rock horizontal well acidification provided by the first aspect of the present application.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] The present application determines permeability based on well logging curves, and divides the reconstruction section of the carbonate horizontal well; the section slug is constructed by high viscosity liquid, the high viscosity liquid is used to realize the section isolation; the acid liquid is uniformly injected, the self-adaptive diffusion in the section is realized by using the acid liquid viscoelasticity and the permeability structure difference; the moving control of the coiled tubing is used to construct the coupling relationship to adjust the acid injection rate and the moving speed; the acid liquid distribution regulation is used to dynamically adjust the acid liquid parameters combined with the flowback fluid and the differential pressure response; the whole well section acidizing operation is executed, all well sections are processed through the slug and the acid injection iteration; the acidizing effect feedback and parameter optimization are used to evaluate and adjust the acidizing parameters based on the flowback fluid and the productivity response. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0036] Figure 1 A flowchart of an optimization method for carbonate horizontal well acidification provided by the embodiments of the present application is shown in the figure;

[0037] Figure 2 A physical section division schematic diagram provided by the embodiments of the present application is shown in the figure;

[0038] Figure 3 A slug construction schematic diagram provided by the embodiments of the present application is shown in the figure;

[0039] Figure 4 A self-adaptive flow schematic diagram of the diverting acid provided by the embodiments of the present application is shown in the figure;

[0040] Figure 5 A coiled tubing moving and acid injection rate coupling control schematic diagram provided by the embodiments of the present application is shown in the figure;

[0041] Figure 6 An acid liquid distribution regulation flowchart provided by the embodiments of the present application is shown in the figure;

[0042] Figure 7 An effect feedback and parameter optimization flowchart provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given to the present application combined with embodiments and drawings, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not limit the present application.

[0044] It is 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 synonyms merely mean to indicate the presence of a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be understood as excluding the presence or possibility of adding one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing.

[0045] Carbonate reservoirs are one of the important oil and gas storage 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 permeability difference of the reservoir is significant, and phenomena such as rapid breakthrough in high-permeability areas and insufficient modification in low-permeability sections often occur, which seriously affect the effectiveness and uniformity of acidification modification.

[0046] Currently, 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 area. However, traditional acidification processes mostly use single continuous pumping methods, which easily lead to the preferential entry of acid into high-permeability channels in strongly heterogeneous reservoirs, resulting in the problem of "non-uniform acidification" with concentrated acid etching and difficult modification of low-permeability areas. In addition, for long horizontal well operations, the acid has a large frictional resistance along the way in the wellbore, and the acid front is prone to lose control, further exacerbating the spatial distribution of acidification efficiency.

[0047] To improve acidification distribution, some existing technologies propose methods such as multi-stage 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 carbonate rock strongly heterogeneous long horizontal wells.

[0048] Therefore, the present application provides an optimization method for carbonate rock horizontal well acidification, which uses the cooperative strategy of "well section plug control + uniform injection of steering acid + tubing movement regulation + dynamic optimization of parameters" to realize the acidification modification of long horizontal wells with a horizontal section length exceeding 1000 meters.

[0049] It is understood that the method provided in the present embodiment is mainly aimed at the acidification of long horizontal wells, such as wells with a length exceeding 1000 meters, and of course the acidification optimization method provided by the present application can also be applied to wells less than 1000 meters.

[0050] Please refer to Figure 1 , Figure 1This is a schematic flowchart illustrating an optimized method for acidizing horizontal wells in carbonate rock, as provided in an embodiment of the present invention. Figure 1 As shown, the method includes:

[0051] S101, obtain the logging curve of a horizontal well in a carbonate rock formation.

[0052] In this embodiment, undisturbed core samples were obtained through logging and core analysis to provide a detailed description of the reservoir's pore structure and lithological assemblage. The focus was on identifying microstructural differences such as fracture development, the proportion of intergranular pores and dissolution pores, to establish a foundation for understanding reservoir heterogeneity. Conventional logging curves, including natural gamma (GR), acoustic transit time (AC), density (DEN), neutron porosity (CNL), and resistivity (RT), were employed.

[0053] S102, based on the logging curves, calculate the equivalent permeability of different well sections, and according to the pre-configured well section conditions, combine the equivalent permeability to divide the carbonate horizontal well into multiple well sections with similar physical properties.

[0054] In this embodiment, addressing the significant formation heterogeneity and complex porosity-permeability structure differences in long horizontal carbonate wells, a multi-source data fusion and physical property feature extraction method is employed to identify and divide the horizontal wellbore into stimulation units, providing a basis for subsequent acidizing parameter matching and injection rhythm control. For example, for long horizontal carbonate wells with a horizontal section length greater than 1000 meters, based on logging, well logging, and core analysis data, the heterogeneity characteristics of the reservoir are identified, and the horizontal section is divided into multiple well sections with similar physical properties according to permeability ranges. For example, the permeability ranges include: less than 10 mD, 10–20 mD, 20–50 mD, 50–100 mD, and greater than 100 mD.

[0055] Based on the logging curves described in step S101, and combined with nuclear magnetic resonance (NMR) logging, the effective porosity is obtained. T2 spectral distribution is used to identify the ratio of free fluid to bound fluid, aiding in the assessment of differences in flow capacity and changes in pore connectivity. Equivalent permeability for different well sections is extracted from well test analysis data. (mD) serves as the basis for quantitative division of well sections.

[0056] To achieve precise segmentation and differentiated acidizing control, well section modeling is performed based on formation physical property identification and permeability differences. Horizontal sections are treated as a heterogeneous permeability continuum. Based on the relative rate of change of permeability between adjacent well sections and the section length criterion, the following well section conditions are adopted: the relative rate of change of permeability between 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. The mathematical expression is as follows:

[0057] wherein, is the equivalent permeability (mD) of the first well section; is the equivalent permeability (mD) of the first well section; is the permeability mutation threshold (value range: 0.3-0.5); is the equivalent permeability (mD) of the first well section; is the horizontal well section length (m) of the first well section; is the minimum effective well section length, set to 20-50 (m).

[0058] When the above conditions are met, the adjacent well sections are divided into two independent physical sections, and the well sections are divided in accordance with the standards in Table 1 below:

[0059] Table 1

[0060]

[0061] 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, and the specific calculation formula is as follows: wherein, is the effective porosity; is the total porosity; is the NMR spectrum area of the free fluid zone (T2>33ms); is the total T2 spectrum area.

[0062] The Coates model is used to estimate the equivalent permeability, and the calculation formula is as follows: wherein, is the equivalent permeability (mD); is the empirical coefficient, and the value range in carbonate rocks is 0.1-100; is the free fluid porosity; is the bound liquid porosity.

[0063] Specifically, W001 well in a W work area is selected as the test object. The area has a strong structure and complex pore-fissure superimposed geological background, and has the typical characteristics of "strong heterogeneity + long horizontal well structure" targeted by the method. The total length of the horizontal section of the well site target section is 1850m, the wellbore is designed as a bare hole horizontal section, and the completion method is a casing + windowed open hole structure.

[0064] The reservoir characteristics are as follows:

[0065] Lithology type: mainly micritic limestone, powdery crystalline limestone, and locally interbedded dolomitic limestone;

[0066] Pore structure: intergranular pores, dissolution pores, intercrystalline fissures and tectonic fractures are developed;

[0067] Strong heterogeneity: porosity 4.2%~12.5%, permeability 0.2~180mD, zonal distribution, spatial variation is violent;

[0068] Horizontal well trajectory: through multiple different stages of dissolution and fracture zone, along the well section reservoir physical property fluctuation frequently.

[0069] In the two rounds of conventional acidizing operation in the well, using 15% HCl full well continuous acid injection method, there are the following typical problems:

[0070] (1) acid liquid preferentially enters high permeability section, resulting in insufficient acid coverage in low permeability section;

[0071] (2) large response difference between sections, uneven reaction;

[0072] (3) multi-section productivity does not increase, P2, P3 section has no obvious stimulation response.

[0073] These problems are completely consistent with the key problems of long horizontal well heterogeneity acidification reconstruction pointed out by the present application, such as "serious flow deviation, low efficiency reconstruction, acid effect concentration", etc. The composite uniform acidification optimization method of "physical property identification + well section plug + steering acid self-adaptation + rhythm promotion + response feedback" proposed by the present application can be used to solve the problems.

[0074] In order to solve the problems of "unbalanced acid liquid distribution between sections, insufficient acid effect in low permeability area" in the acidification reconstruction of W001 well, first, the well section physical property identification and well section division are carried out. The conventional logging + imaging logging (FMI) + nuclear magnetic resonance (NMR) joint analysis is used to identify lithology, pore type and fluid migration capacity.

[0075] Based on the T2 spectrum extracted by nuclear magnetic resonance (NMR), the free fluid area (T2>33ms) and the bound area 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.

[0076] Taking P2 section as an example, the nuclear magnetic resonance logging data shows that the free fluid index FFI=8.5%, the bound fluid index BVI=7.2%, accordingly, the total porosity =15.7% (the total porosity is the sum of movable and bound fluid volume in NMR logging), then according to the formula, the effective porosity is calculated, which shows that P2 section has good acid liquid response basis, and is expected to obtain obvious reconstruction gain effect in subsequent acidizing operation.

[0077] The equivalent permeability is inversed by using the Coates model, and the formula is wherein, is the equivalent permeability (mD), is the free fluid porosity; is the bound fluid porosity, is an empirical coefficient. Taking the P5 section as an example, FFI = 13.1%, = 5.6%, the measured = 17.29 mD, and the empirical coefficient is inversed by using the formula Therefore, the empirical coefficient C = 3.16 is used for the permeability inversion of other well sections in this embodiment.

[0078] The equivalent permeability of all the 8 physical property well sections is calculated as The error between the inversed value and the measured value in this paper is generally controlled within ± 5%, and the maximum error is not more than ± 11%, which verifies the applicability of the parameters and the reliability of the calculation method.

[0079] In this embodiment, the effective porosity of each well section is calculated according to the logging, NMR and logging data and the equivalent permeability The physical property of the horizontal section of the W001 well is divided in combination with the well depth range, and 8 well sections are identified, which are shown in the following Table 2:

[0080] Table 2

[0081]

[0082] Based on Table 2, the equivalent permeability of the well sections P1, P2 and P3 is less than 10 mD; the equivalent permeability of the well sections P4 and P5 is between 10 and 20 mD; the equivalent permeability of the well sections P6 and P7 is between 20 and 50 mD; and the equivalent permeability of the well section P8 is between 50 and 100 mD. In order to show the permeability difference and pore structure characteristics of each well section, a physical property well section division schematic diagram is drawn, as shown in Figure 2 Each physical property section in each interval is regarded as an acidification control unit with similar response characteristics, which is convenient for the parameter linkage matching of the acid concentration, slug volume and acid injection rate, and realizes the coupling control of the acid liquid propulsion rhythm and the reservoir liquid absorption capacity.

[0083] In S103, the buffer distance of each well section is calculated according to the injection flow rate of the acid liquid, the open hole diameter and the expected residence time of the acid liquid and the rock reaction, and the design length of the slug is determined according to the buffer distance.

[0084] In the embodiment, the slug construction of the high-viscosity liquid in the well section is the key measure to realize the independent acidizing of each well section. The key point is to form a stable liquid isolation barrier at the starting position of each well section by pumping the high-viscosity slug liquid through the coiled tubing, to block the preferential channeling of the acid liquid in the high-permeability section, and to ensure the full action of the acid liquid in the target well section.

[0085] The slug arrangement is combined with the results of the well section division in step S102, and the starting point of the well section, the position of the permeability mutation of the formation, and the acidizing response sensitivity are preferentially considered. 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, a guar gum-based high-molecular liquid system to form a stable suspended colloid, and the design viscosity range is: wherein, The slug liquid viscosity (mPa·s) needs to consider the construction temperature (60-90°C), the formation pressure (25-45 MPa), and the shear environment of the wellbore.

[0086] 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 to block the invalid channeling of the acid liquid in the high-permeability channel. To prevent the channeling between the slug liquids of adjacent well sections, the minimum safe buffer distance needs to be calculated according to the acid injection flow rate, the wellbore diameter, and the target reaction residence time, and the slug design length is determined on this basis. To avoid the crosstalk of multiple slug liquids, the buffer distance of the slug can be calculated, and the formula is: wherein, The buffer distance between the front edge of the slug and the acid section (m); The subsequent acid injection flow rate; The designed reaction residence time (min).

[0087] The design length of the slug is determined according to the buffer distance of the slug of each well section, and the total pumping 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, The single-section slug volume; The wellbore inner diameter (m); The design length of the slug liquid column, which is generally designed to be 3-8 m.

[0088] For example, after completing the full-well-section property identification and 8-section reconstruction unit division, to realize the physical isolation of the acid liquid between different permeability sections and limit the channeling, the high-viscosity slug liquid + coiled tubing pushing method proposed in the application is used to construct the slug barrier, and the independent reaction environment of the acid liquid in each section is ensured.

[0089] The plug liquid formula selects a downhole high-temperature shear-resistant polymer cross-linking plug system, which is composed of: main cross-linking group: modified hydroxypropyl guar gum (1.5%); bonding enhancer: polyacrylamide (0.3%); cross-linking agent: slow-release borate (0.15%); filtrate reducer: micro-particle plugging agent (0.05%); temperature adaptability: ≤160℃; viscosity actually measured: ≥200 mPa·s (100℃, 170s -1 ). The system can achieve effective plugging between segments for ≥20 min in high-permeability fractured segments without obvious backflow.

[0090] The plug volume is calculated by the formula , wherein, is the open hole diameter, which is measured on site to be 0.165 m; is the plug liquid column design length, which is divided into 3-8 m according to the segment liquid absorption capacity of physical properties. A safety compensation coefficient is added to adjust the plug volume, and the calculation formula becomes .

[0091] Taking the P5 segment as an example, the plug length is designed to be , the wellbore inner diameter is ; by calculation , considering the liquid absorption compensation, the final plug volume is calculated to be .

[0092] To ensure the stability of on-site construction, the final volume of each plug liquid is set as shown in Table 3 below:

[0093] Table 3

[0094]

[0095] The plug liquid injection is completed by using a coiled tubing, and the construction is performed in reverse order from the wellbore bottom to the wellhead direction to ensure the stability of the liquid gravity and the integrity of the lower plug. After each plug is injected, a short static state should be maintained to ensure that the plug liquid forms a homogeneous segment in the wellbore without stratification or collapse. As can be seen from the above table, the P8 segment is a high-permeability zone, and a double-plug parallel sealing structure (with a 15 m interval between the front and rear plug liquids) is used on site to ensure that the acid liquid does not flow to the high-absorption segment. Please refer to Figure 3 for the plug integrity and isolation verification. During the on-site construction process, a micro-flowback pressure test is used to detect the plug barrier effect: the flowback segment 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.

[0096] The embodiment proposes a new mechanism for fine acidizing of well segments for strong heterogeneous carbonate reservoirs, which realizes acid liquid physical isolation control through high-viscosity plugging to ensure the independence and uniformity of each well segment during the acidizing process.

[0097] S104, the diffusion index of the acid liquid in 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.

[0098] In this embodiment, the acid liquid is a diverting acid liquid with self-diverting capability, and a self-diverting acid with self-diverting capability is injected in each physical well section. By using the viscoelasticity and rheological properties of the acid liquid and combining the differences in the pore and permeability structure of the reservoir, self-adaptive flow and uniform distribution of the acid liquid in the section are achieved, and the reconstruction effect of the low permeability area is enhanced.

[0099] The diverting acid liquid is a composite system composed of a viscoelastic thickening agent, a surfactant and a retarding reaction agent. 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 by increasing pH value, and is preferably suitable for reservoir well sections with a permeability of less than 50 mD. In the formation with low porosity and weak flow capacity, the acid liquid can realize spontaneous diversion and uniform diffusion, and effectively improve the acidizing production degree of the low permeability area.

[0100] After the acid liquid is injected into the target well section, its diverting and diffusing ability is mainly controlled by the viscosity of the acid liquid, the micro pressure difference and the local permeability, and its diversion 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).

[0101] As a specific embodiment, the present embodiment controls to ensure that the acid liquid has effective self-diverting capability and avoids concentrated acid etching in high permeability channels.

[0102] 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 control 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; is the total number of micro paths that the acid liquid can enter in the well section.

[0103] Based on the fluid propulsion theory, the effective range of the acid liquid in the reservoir can be estimated, and the formula is as follows: wherein, is the action radius of the acid fluid (m); is the average permeability of the interval (mD); is the effective reaction residence time of the acid fluid in the interval (min); is the formation porosity (dimensionless); is the viscosity of the acid fluid (mPa-s).

[0104] For the purpose layer of W001 well in W work area, carbonate pore and fracture development degree and liquid absorption heterogeneity, the following composite diverting acid fluid system is selected, as shown in Table 4 below:

[0105] Table 4

[0106]

[0107] In order to evaluate whether the acid fluid can effectively enter the low permeability channel, the formula wherein, is the viscosity of the acid fluid (mPa-s); is the local pressure drop gradient (MPa / m); is the permeability of the interval (mD). Taking P2 interval as an example, , , , the calculation gives . This value indicates that the acid fluid has certain diverting diffusion capacity and can deviate 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.

[0108] In order to further control the acid fluid distribution in the interval, a dynamic injection model based on flow resistance factor is constructed: wherein, is the acid fluid flow rate injected into the first branch; is the total acid injection flow rate of the interval; is the relative flow resistance factor of the first branch; is the total number of micro-paths that the acid fluid can enter in the interval. Taking P5 interval as an example, assuming that there are 3 micro-channels with flow resistance factors of , the total acid injection rate , then , , which indicates that the acid fluid actively enters the channel with smaller resistance, realizing predictable and controllable distribution balance in the interval in engineering. By adjusting the injection proportion of different branches, the acid fluid can be moderately deviated to the path with weak liquid absorption capacity, thereby improving the uneven distribution of acid fluid.

[0109] Based on the fluid propulsion theory, the action radius of the acid liquid in a certain section of the well 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 shows 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 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.

[0110] After each section of acidification, the uniformity and acid response are immediately judged by the following means: the pH and Fe 2+ peak value of the flowback fluid judges the acid corrosion activity;The well section differential pressure ΔP is monitored in real time, and ΔP<1.5MPa indicates that the reaction is insufficient;Whether the conductivity curve is a single-peak decay type, if the fluctuation is violent, there may be slug penetration or acid liquid deflection. 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 ≥0.18m 3 .

[0111] 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.

[0112] 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,

[0113] In the embodiment, the moving 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 regulation and control mode of speed control propulsion and quantitative injection in the carbonate rock long horizontal well acidification operation, and ensure the uniformity of the acid liquid reaction and the sufficiency of the acid corrosion effect in each section of the well.

[0114] The present application establishes a coupling relationship between the acid liquid reaction residence time and the tubing moving speed , the well section length , and the expression of the coupling relationship is: wherein, determined by step S102.

[0115] This embodiment introduces a coupling control model of coiled tubing moving speed and acid injection rate, dynamically controls acid liquid propulsion path and reaction residence time, and realizes adjustable and predictable acid etching process.

[0116] According to the characteristics of large liquid absorption capacity variation and strong heterogeneity of carbonate reservoir, the moving speed and the acid injection rate need to be positively coupled with the local liquid absorption capacity of the reservoir to dynamically adapt to the formation response conditions of different sections.

[0117] In the actual construction process, the moving 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 formation liquid absorption rate and the change of flowback pressure are dynamically fed back through the acidizing real-time monitoring system to adjust to ensure the target range of balanced reaction.

[0118] To realize the quantitative injection, stable propulsion and balanced reaction of acid liquid in the process of carbonate rock long horizontal well acidizing operation, 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 acid liquid between the wellbore and the reservoir, and to ensure the uniformity of acid liquid reaction and the sufficiency of acid etching effect in different physical property well sections.

[0119] Please refer to Figure 5 , combined with the coupling relationship provided by this embodiment, the coupling control of tubing movement and acid injection rate is realized.

[0120] Taking P3 section as an example, the permeability is 7.11 mD (medium-low permeability layer), the length of this section is , the initial setting of the coiled tubing propulsion speed is , and the calculation by the formula is 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, there is a risk of “slow propulsion”, and the construction parameters need to be adjusted.

[0121] If the moving speed of the tubing is adjusted to , and the original acid injection displacement is maintained, then the recalculation is: , which meets the target range. The field can adjust the speed appropriately according to the feedback of the formation liquid absorption capacity, and the flowback liquid pH and ΔP recovery curves are normal, verifying the effective control.

[0122] The acidizing construction of this well section uses the field monitoring system: the ground acid injection parameters , are adjusted online; the downhole pressure sensor returns ΔP in real time; the conductivity and Fe2+ Concentration determines whether the reaction is complete; on-site assessment is based on real-time data. The calculation results, and the recommended construction parameters are shown in Table 5 below:

[0123] Table 5

[0124]

[0125] S106. Optimize acid injection for each horizontal well section by selecting either an equal-volume acid injection strategy or a differential acid injection strategy.

[0126] In this embodiment, acid distribution control is the core regulation mechanism for achieving uniform acidification throughout a long horizontal well in carbonate rock. The acid distribution strategy selects equal-volume or differential acid injection modes based on the permeability and lithological sensitivity of each well section. Furthermore, it incorporates the conductivity trends of short-cycle flowback fluid and acid consumption analysis results to adjust the injection system parameters in real time, adapting to differences in fluid absorption capacity and reaction conditions between sections.

[0127] First, in the operation design phase, based on the equivalent permeability of each well section obtained in step S102... It is preferable to adopt one of the following two strategies:

[0128] Equal-volume acid injection strategy: Applicable to medium-to-high permeability sections or similar reservoir sections, where the same volume of acid is injected into all well sections. The formula is: .

[0129] Differential acid injection strategy: Suitable for situations with significant differences in permeability. The acid volume is allocated according to the permeability normalization coefficient, as shown in the following formula: ,in, For the first The volume of acid injected into the segment; This represents the total design volume of acid fluid throughout the entire well section; The equivalent permeability (mD) of a certain well section; This represents the total number of well sections. The acid distribution principle is that the permeability value increases, and the corresponding acid volume decreases accordingly.

[0130] This strategy ensures that the acid is "differentiatedly distributed" according to the differences in the fluid absorption capacity of the well section, avoiding phenomena such as excessive acid in high-permeability sections and insufficient acid in low-permeability sections.

[0131] During acid injection, short-cycle backflow fluid analysis and inter-section differential pressure response monitoring are implemented based on the coiled tubing location and acid injection parameters to determine whether the acidization process of the current section meets the standards. The following two types of indicators are used for control:

[0132] (1) The change rate of the conductivity of the flowback fluid (%): used for judging the reaction degree of the acid liquid; (2) The change trend of the pressure difference (ΔP) before and after the slug: used for judging the acid liquid propulsion integrity.

[0133] When the change trend of the conductivity of the 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 the 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).

[0134] Based on the above judgment results, 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.

[0135] 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.

[0136] 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 results to adapt to the inter-zone liquid absorption capacity and acid etching reaction condition differences.

[0137] 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 .

[0138] In the acid liquid injection process, the change rate of the conductivity of the 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.

[0139] 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.

[0140] In some embodiments, the method further comprises: measuring the maximum injection volume and the minimum injection volume of the acid liquid for each well section, calculating the injection balance coefficient of each well 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 well section, calculating the average value of the differential pressure of all well sections according to the real-time differential pressure, and calculating the differential pressure response coordination coefficient of each well section acidification according to the real-time differential pressure and the average value.

[0141] Specifically, the full-section acidification operation is performed on the basis of completing well section identification, slug construction, acid injection parameter design, and acid injection response regulation, implementing the inter-slug acidification circulation construction process throughout the entire horizontal well section, and ensuring that the carbonate long horizontal well realizes uniform acid coverage and efficient use under the condition of heterogeneous reservoir. The core of this embodiment is a composite acidification mode combining "well section slug construction + diversion acid injection + coiled tubing movement + response regulation", which adopts a construction mechanism of inter-slug propulsion, parameter linkage, and rhythm control, and develops acidification operation from the distal end to the proximal end of the wellbore section by section, ensuring that the acid etching reaction covers no omissions and the response effect is coordinated and unified.

[0142] To realize the uniformity control of the full-well-section acid liquid injection distribution, an acid liquid inter-slug 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 well section; is the total number of well sections. When , it indicates that the inter-slug acid liquid injection amount is balanced, which is beneficial to realize the consistency of acid liquid propulsion. Conversely, if A value that is too high indicates a significant difference in acid distribution between sections, necessitating adjustments to the acid injection strategy.

[0143] Meanwhile, to evaluate the synchronicity and coordination of the acidizing reaction process in each well section, an acidizing response coordination coefficient is introduced, expressed as follows: ,in, This is the pressure difference response compatibility coefficient; For the first Real-time pressure difference (MPa) during the acid injection process. This represents the average pressure difference across all well sections (MPa). This represents the total number of well sections. This differential pressure response coordination coefficient is used to determine the degree of difference in propulsion resistance of acid in different well sections. The higher the coordination, the more uniform the acid response process and the smaller the difference between sections.

[0144] For example, maintaining during construction The pressure should be less than 0.3 MPa to control the risk of uneven acidification.

[0145] This embodiment adopts a reverse-order segment construction sequence, advancing from the farthest end of the wellbore towards the wellhead, and completes the following operations in sequence:

[0146] High-viscosity fluid is pumped into the coiled tubing, and an isolation plug is constructed at the top of the current section, with a thickness controlled at 3.5–5.0 m.

[0147] Inject a predefined steering acid system with a displacement of 0.4–0.8 and an oil line speed of 2.5–4.0 m / min;

[0148] After each injection, let it stand for 3–5 minutes, collect the backflow fluid and perform dual parameter diagnosis of conductivity and differential pressure.

[0149] Based on feedback, adjust the acid concentration, residence time, or slug volume of the next stage in real time.

[0150] The acid injection cycle was completed sequentially from well section P1 to well section P8, with a total construction time of 21 hours.

[0151] The uniformity of the entire acid injection process is evaluated using the acid volume distribution balance coefficient, derived from the formula... ,in, This is the acid injection volume distribution equilibrium coefficient; For the first Acid injection volume for each well section; This represents the total number of well sections. Based on the differential acid injection design mentioned above, P1=148.1, P8=3.5, the following calculations are performed: The results show that the value is too high. This is because a "strong differential acid injection strategy" was used to intensify acid etching in low-permeability sections. According to the runoff data, the acid effect distribution is basically balanced, indicating that the strategy is reasonable. However, if a mixed approach of "differential injection + intra-section rebalancing" is used, the value can be further reduced. Below 10.0. (Passed) Reaction Coordination Evaluation Formula The pressure difference data was calculated. The pressure was 0.34 MPa, indicating that the reaction synchronicity was close to the control threshold (0.3 MPa). Subsequent construction recommendations suggest increasing the acid residence time or using a stronger, slower-responding agent to control reaction synchronicity. Based on the implementation results, The value reached 42.3, indicating a large difference in acid injection volume between segments, matching a strongly heterogeneous structure; however, The pressure was 0.34 MPa, close to the critical value, indicating that the inter-segment propulsion pressure was not yet fully coordinated. It is recommended that future engineering projects further combine these two indicators to adjust the slug volume and acid injection rhythm in a coordinated manner, achieving dual optimization of acid distribution and reaction synchronization.

[0152] In some embodiments, the prior art for evaluating the acidizing effect of horizontal wells generally only considers the impact on production capacity, which leads to insufficient accuracy in the analysis of the acidizing effect. Therefore, the method provided in this embodiment further includes: measuring the flowback fluid response factor, differential pressure response factor, and production capacity response factor of the carbonate horizontal well before and after acidizing; performing a weighted summation of the flowback fluid response factor, differential pressure response factor, and production capacity response factor to calculate the analytical value of the acidizing response; and optimizing the acidizing parameters of carbonate horizontal wells in similar formations or the same carbonate horizontal well based on the analytical value.

[0153] Specifically, after completing the acidizing operation of the entire well section, this embodiment comprehensively evaluates the actual acidizing effect of each physical property section through methods such as flowback fluid detection, differential pressure change analysis and production capacity response evaluation. Based on this, the acid fluid parameter configuration, slug design and acid injection control strategy are optimized to construct an acidizing closed-loop regulation and rolling improvement mechanism.

[0154] Please see Figure 7 The analysis of the acidification effect is mainly carried out from the following three dimensions:

[0155] (1) Flowback liquid indicators: including pH value, Ca 2+ Concentration, conductivity, etc., are used to determine the intensity of the reaction and the degree of karst dissolution;

[0156] (2) Pressure difference response characteristics: By measuring pressure at multiple points, the change in pressure difference ΔP before and after acidizing the slug is analyzed to evaluate the acid propulsion effect and slug integrity;

[0157] (3) Capacity improvement: By comparing the single-stage liquid production, test flow pressure, and oil-gas-water ratio before and after acidification, the improvement effect of acidification is determined.

[0158] To realize quantitative evaluation, the analysis function of acidification response is constructed, and the formula is as follows: , wherein, is the acidification response comprehensive score of the first well section (0-1, the higher the value, the better the improvement effect); is the capacity response factor, which is calculated by normalizing the yield improvement amplitude; is the flowback fluid response factor, which is constructed based on the pH, Ca 2+ change amount; is the pressure difference response factor, reflecting the pressure difference change amplitude before and after the slug; is the weight coefficient of the corresponding factor, and the values are 0.5, 0.3 and 0.2, respectively.

[0159] The embodiment establishes a feedback control mechanism based on the conductivity of flowback fluid, pH value and pressure difference response, which can realize real-time optimization and response closed loop of parameters during construction.

[0160] According to the analysis results calculated by the function, the parameter optimization of subsequent similar formations or subsequent acidification stages of the same well section is carried out, including but not limited to:

[0161] If , it indicates that the acidification effect is weak, and it is suggested to increase the acid injection concentration or appropriately prolong the residence time;

[0162] If is significantly low, it indicates that the slug stability is insufficient or the acid liquid channeling risk is high, and it is suggested to increase the slug volume or adjust the interval distance;

[0163] If is high, and is significantly low, it indicates that the acid has been fully reacted, and a low-cost weak acid replacement system can be selected subsequently.

[0164] 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.

[0165] Exemplarily, the well section data analysis (part) of S7 well is shown in Table 6 as follows:

[0166] Table 6

[0167]

[0168] ​From the above table 6 can be feedback analysis and then the optimization of parameters:

[0169] If P8, the acid concentration is increased to 20%, or reduce the rate of advance, extend the reaction time.

[0170] If Low (such as P8), increase the slug volume or use double slug isolation technology, to raise the acid front differential pressure.

[0171] If High and Low (such as P5), consider the subsequent segment optimization weak acid system or slow reaction combination, to improve the reaction efficiency and economy.

[0172] In the above described embodiments, the well section acidizing operation specific implementation process as follows:

[0173] (1) according to the division of each well section, using reverse sequence construction method, that is, from the end of the wellbore paragraph, in turn to the wellhead direction;

[0174] (2) in each well section, first implement high viscosity slug injection and positioning, to establish the intersegment liquid isolation barrier;

[0175] (3) then turn to acid uniform injection, acid ratio, concentration, injection rate and coiled tubing moving speed in accordance with the set parameters;

[0176] (4) after the acid injection, into the short time standing or micro flowback stage, real-time monitoring of slug stability and flowback fluid conductivity change trend;

[0177] (5) if the flowback fluid conductivity, acid consumption change or intersegment differential pressure response is abnormal, according to the dynamic control mechanism, the next segment acid injection parameters are adjusted;

[0178] (6) repeat the execution of each well segment slug construction, acid injection and moving control, etc., until cover all well sections, realize acid from far to near, continuous advance, feedback loop intersegment acidizing operation.

[0179] In the operation process, combined with the coiled tubing depth real-time identification system, downhole pressure change monitoring system and ground acid control interface, establish wellbore advance rhythm model and well section acid injection execution sequence. The rhythm model includes the key variables such as each segment construction time, intersegment switching delay, flowback judgment time window, used to regulate acid advance rhythm and operation window matching. After each two well sections are completed, the stage flowback analysis and ground pressure curve analysis are carried out to evaluate the slug integrity, acid distribution uniformity and construction accuracy, to ensure the continuity, stability and well section coverage integrity of acidizing operation process.

[0180] The embodiment of the present application also provides an electronic device. The electronic device comprises 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 comprises, but is not limited to, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (PROM) or a compact disc read-only memory (CD-ROM), and is used for storing relevant instructions and data.

[0181] The communication interface is used for receiving and sending 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 used to read one or more programs stored in the memory and perform the following operations: obtaining a well logging curve of a 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 acid liquid, a bare hole diameter and an expected residence time of acid liquid and rock reaction, and determining a design length of the slug according to the buffer distance; calculating a diffusion index of 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 a reservoir; constructing a coupling relationship among acid liquid reaction residence time, tubing moving speed, acid injection rate and 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 acid injection of each horizontal well section.

[0182] It should be noted that the specific implementation of each operation can be described in the method embodiment of the above Figure 1 The electronic device can be used to perform an optimization method of carbonate rock horizontal well acidification, and details are not described herein again.

[0183] 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. In addition, one or more instructions suitable for being loaded and executed by the processor are also 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 such as 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. Moreover, 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.

[0184] 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.

[0185] The above detailed description further explains the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above 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 of optimization of carbonates horizontal well acidizing, characterized in that the method The method comprises: obtaining the logging curves of the carbonate rock horizontal well; calculating the equivalent permeability of different well sections according to the logging curves, 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 each well section according to the injection flow rate of the acid liquid, the open hole diameter and the expected residence time of the acid liquid and rock reaction, and determining the design length of the slug according to the buffer distance; The diffusion index of the acid liquid in each well section is calculated according to the viscosity of the acid liquid, the local pressure drop gradient of the acid liquid in the reservoir along the channel direction and the local permeability; wherein, the calculation formula of the diffusion index is: Wherein, viscosity of the acid liquid; local pressure drop gradient of the acid liquid in the reservoir along the micro-channel direction; local permeability; After the diffusion index is calculated, the method further comprises: analyzing whether the acid liquid has the ability to turn into the low-permeability area according to the diffusion index, and if the acid liquid has the ability to turn into the low-permeability area, then calculating the branch injection flow and the action radius of the acid liquid in each well section. constructing the coupling relationship among the acid liquid reaction residence time, the tubing moving speed and the well section length, and adjusting the injection rate of the acid liquid injected into the tubing according to the coupling relationship; selecting the equal acid injection strategy or the differential acid injection strategy to optimize the acid injection of each horizontal well section.

2. The method of optimizing carbonate horizontal well acidizing of claim 1, wherein, The well section conditions are specifically that the 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.

3. The method of optimizing carbonate horizontal well acidizing of claim 1, wherein, The expression of the coupling relationship is: wherein, is the acid liquid reaction residence time; is the moving speed of the oil pipe; is the length of the well section.

4. The method of claim 1, wherein, 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 normalization 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 normalization coefficient.

5. The method of claim 1, wherein, The method further comprises: during the acid injection into each well section, judging whether the acidification of each well section is up to standard according to the change rate of the conductivity of the flowback fluid and the change trend of the pressure difference before and after the slug; if the acidification is not up to standard, calculating a reference value of the adjusted slug volume according to the standard pressure difference response reference value and the measured pressure difference.

6. The method of optimizing carbonate horizontal well acidizing of claim 1, wherein, The method further comprises: 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 of each well section, calculating the average value of the pressure differences 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.

7. The method of optimizing carbonate horizontal well acidizing of claim 1, wherein, 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 the acidification; performing weighted summation on the flowback fluid response factor, the pressure difference response factor and the productivity response factor to calculate the analysis value of the acidification response; optimizing the acidification parameters of the carbonate rock horizontal well with similar formations or the same carbonate rock horizontal well according to the analysis value.

8. An electronic device, comprising: The electronic device comprises a memory and a processor; the memory is used to store a computer program, and the computer program comprises program instructions; the processor is used to execute the program instructions, so that the electronic device performs the steps of the optimization method for the acidification of the carbonate rock horizontal well according to any one of claims 1 to 7.

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