Method for determining water plugging amount of fractured reservoir and application

Abstract

The invention provides a method for determining the water plugging amount of a fractured reservoir and application, and belongs to the technical field of oilfield development. The method comprises the following steps that based on seismic data inversion, landmark software is adopted to describe a single-well oil reservoir fracture-cavity structure, and the position relation between the structures is determined; a t-Navigator data body of Petrel software is adopted for analysis, and a water invasion path is defined; calculating the dominant channel volume of the water invasion path; drawing a relation curve of a water-oil ratio and a water production rise rate according to production dynamic data, and calculating a pre-estimated dynamic bottom water invasion amount; comparing the dynamic bottom water invasion amount with the dominant channel volume simulated by the geologic model, and taking the minimum value of the dynamic bottom water invasion amount and the dominant channel volume as the use amount of the fractured reservoir water plugging agent; the invention further provides application of the method in water plugging of an oil well. Compared with the prior art, the method solves the problem that in the prior art, a water plugging consumption calculation method suitable for the fractured reservoir is lacked.

Description

Technical Field

[0001] The present invention belongs to the technical field of oilfield development, and particularly relates to a method and application for determining the water plugging dosage in a fractured reservoir. Background Art

[0002] The storage medium of the Tahe fractured-vuggy reservoir consists of solution caves, fractures, and solution pores, with discontinuous distribution. Due to its dominant fracture channels and strong bottom water, the bottom water rapidly channels along the dominant fractures, resulting in high water cut in oil wells and affecting the ultimate recovery rate of oil wells. Due to the special reservoir structure of carbonate reservoirs, oil wells are mainly drilled in the enriched areas. Therefore, water plugging is another important means following the enhanced oil recovery technology by gas injection. Currently, there are more than 200 water plugging measures per year in the Tahe Oilfield, with an economic efficiency of less than 60%, and only 20% of the wells are highly effective. The main factor affecting the water plugging efficiency is the dosage of the plugging agent. Currently, the commonly used method is the empirical method: the analogy method, which guides the water plugging dosage of other wells based on similar effective wells. This method can hardly consider the differences of the wells themselves and hinders the development of petroleum extraction technology. Therefore, there is an urgent need for a more effective method to determine the water plugging dosage.

[0003] The Chinese patent "A Method, Device, Electronic Equipment, and Storage Medium for Determining the Dosage of a Water Plugging Agent" with patent application number CN114925547A involves a method and device for determining the dosage of a water plugging agent. The method pre-determines a multi-layer reservoir model of the area to be injected with the agent. The method includes: determining the diversion rate after injecting the agent into the first sub-layer according to the multi-layer reservoir model, where the first sub-layer is the sub-layer with the highest permeability; determining the expected effect coefficient of the water plugging agent in the area to be injected with the agent according to the diversion rate after injecting the agent into the first sub-layer and the diversion rate after injecting the agent into the i-th sub-layer; determining the permeability after injecting the agent into the first sub-layer according to the diversion rate after injecting the agent into the first sub-layer; determining the action radius of the water plugging agent in the area to be injected with the agent according to the expected effect coefficient of the water plugging agent and the permeability after injecting the agent into the first sub-layer; and determining the dosage of the water plugging agent in the area to be injected with the agent according to the preset water plugging agent dosage calculation model and the action radius of the water plugging agent. By this method, it is avoided that inaccurate dosage of the water plugging agent leads to reservoir pollution caused by excessive injection or the inability to achieve the effect of sand consolidation and water plugging due to too small injection dosage. However, this invention only considers the design of the dosage of the plugging agent in sandstone homogeneous reservoirs and is difficult to be applied to fractured reservoirs and thus cannot be used for reference.

[0004] The Chinese patent "A Method and System for Calculating the Dosage of Flow-Regulating Channel Plugging Agent in Fractured-Vuggy Reservoirs" of patent application CN115146427A discloses a method for calculating the dosage of flow-regulating channel plugging agent in fractured-vuggy reservoirs, including: collecting tracer test data and dynamic production data of injection-production well groups in the reservoir unit to be studied; determining the number of flow channels in the well-to-well groups with connectable relationships in the current unit according to the tracer test data of the injection-production well groups; based on the dynamic production data, using reservoir engineering theory to conduct an analysis of the effectiveness of the injected water in the current unit, calculating the water diversion volume of the unit after water injection, and further obtaining the corresponding flow channel volume; calculating the dosage of the plugging agent in the specified flow-regulating direction according to the flow channel volume and the number of flow channels in each well-to-well group, using the proportion of the number of flow channels to be regulated in the specified flow-regulating direction to the total number of all flow channels related to the current flow-regulating direction. The present invention examines the water breakthrough volume between well groups, mainly referring to the dynamic response data between wells. It has no guiding effect on the dosage of single-well water-invasion plugging agent and cannot be used for reference.

[0005] The Chinese patent "A Method for Determining the Dosage of Acid-Fracturing Temporary Plugging Agent in Carbonate Oil and Gas Reservoirs" of patent application CN116411912A provides a method for determining the dosage of acid-fracturing temporary plugging agent in carbonate oil and gas reservoirs. The method includes: obtaining the fracture width and fracture height of the target reservoir fractures during the acid-fracturing construction process; obtaining the relationship between the plugging depth and the plugging pressure of the temporary plugging agent through indoor simulation experiments; where the plugging depth refers to the distance that the temporary plugging agent enters the fracture; based on the fracture width and fracture height of the target reservoir fractures, and the relationship between the plugging depth and the plugging pressure, combined with the fracture pressure difference of the well section that needs to be plugged in the target reservoir fractures, determining the dosage of the acid-fracturing temporary plugging agent. The technical solution provided by the present invention realizes the quantitative optimization of the dosage of the temporary plugging agent for acid fracturing by combining indoor plugging evaluation experiments, solves the problem of lack of method guidance for the dosage of the previous temporary plugging agent, and greatly improves the success rate of plugging. However, the present invention only considers the dosage of the temporary plugging agent in artificial fractures, which has a large difference from natural fractures and cannot guide the dosage of the plugging agent in natural fractures.

[0006] The literature "Discussion on the Calculation Method of the Dosage of Selective Water Plugging Agent in Bottom-Water Reservoirs, Petrochemical Industry Application, July 2016" proposes different calculation methods for the dosage of plugging agents for bottom-water communication type and bottom-water coning type flooded wells. Based on optimizing the water plugging radius by reservoir numerical simulation, corresponding mathematical models are established according to the different plugging mechanisms of different types of plugging agents, realizing the segmented plug calculation of the dosage of the plugging agent; at the same time, using the Fracpropt three-dimensional fracturing simulation software to invert the fracturing construction, and optimizing the dosage of the plugging agent by simulating and calculating the fracture parameters. For the first time, the organic combination of the fracturing simulation software and the water plugging process is realized, improving the pertinence of the calculation method. Through the verification of the on-site implementation effect, this method can greatly improve the technical effect of plugging the bottom water. However, the literature only targets fractured wells in sandstone reservoirs and cannot guide the dosage of plugging agents in natural fracture reservoirs.

[0007] The literature "Calculation of the dosage of fracture plugging agent in low-permeability reservoirs, Fault-block Oil & Gas Field, May 2013" pointed out that when fracturing and putting into production in low-permeability reservoirs, artificial fractures coexist with natural fractures, resulting in serious water flooding in corner wells while water injection in edge wells is ineffective. To increase the water flooding sweep efficiency, profile control and water shutoff are commonly used stimulation measures. However, at present, the effect of profile control and water shutoff in such reservoirs is poor and the success rate is low. Through comprehensive analysis, it is found that the key problem affecting the effect of profile control and water shutoff is that the filtration of the plugging agent from fractures to the matrix is not considered in the design of traditional profile control and plugging schemes, and the designed dosage of the plugging agent is too small. Based on the seepage theory, the seepage equations of the fracture system and the matrix system are established in this paper. Considering the filtration of the plugging agent under different reservoir physical properties and plugging agent properties, the ratio of the total amount of the plugging agent to the filtration amount under different conditions is deduced, which can be used to guide the design of specific profile control and water shutoff schemes and obtain the optimal dosage of the plugging agent. Through the verification of the on-site implementation effect, this method can greatly improve the technical effect of profile control and plugging; however, the porosity of the fractures in this literature is small, and the actual volume of the plugging agent entering the fractures is very limited. It mainly calculates the dosage of the plugging agent entering the matrix by seepage and cannot guide the calculation of the dosage for plugging large-scale natural fractures.

[0008] None of the above existing technologies involve the calculation method for the water shutoff dosage in carbonate large-scale fractured reservoirs. There is an urgent need for a calculation method for the water shutoff dosage in fractured reservoirs to optimize the scheme design and guide efficient water shutoff on site. Summary of the Invention

[0009] Aiming at the lack of a calculation method for the water shutoff dosage in carbonate large-scale fractured reservoirs in the existing technology, the present invention provides a method for determining the water shutoff dosage in fractured reservoirs to guide efficient water shutoff on site.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for determining the water shutoff dosage in fractured reservoirs, comprising the following steps:

[0012] (1) Based on seismic data inversion, use landmark software to describe the fracture-cavity structure of the single-well reservoir, and clarify the positional relationship between the open hole section of the wellbore and the fracture and cavity structures;

[0013] (2) According to the positional relationship clarified in step (1), use Petrel software to analyze the t-Navigator data volume to clarify the water invasion path;

[0014] (3) Use Petrel software to calculate the volume of the dominant channel of the water invasion path described in step (2); this volume is from the part below the wellbore to the oil-water interface.

[0015] (4) Draw a curve of the water-oil ratio and the water production increase rate according to the production dynamic data, and calculate the estimated dynamic bottom water invasion volume;

[0016] (5) By comparing the dynamic bottom water invasion volume with the volume of the dominant channels simulated by the geological model, the minimum value of the two is taken as the dosage of the water plugging agent for the fractured reservoir.

[0017] Preferably, the method for clarifying the water invasion path in step (2) includes the following steps:

[0018] ① Identify static connected channels based on seismic attributes;

[0019] ② On the basis of step ①, carry out the identification of dynamic connected paths, and simulate streamlines using the t-Navigator data volume of Petrel software, and finally form a comprehensive water flooding path identification method;

[0020] ③ Clarify the water invasion path according to the water flooding path identification method formed in step ②.

[0021] Further preferably, the seismic attributes in step ① include coherence, ant body, and tensor.

[0022] Most preferably, the method for carrying out the identification of dynamic connected paths in step ② includes using tracers and well interference.

[0023] Preferably, the method for calculating the volume of the dominant channels using Petrel software in step (3) includes the following steps:

[0024] Set the porosity to 1%, and divide the data volume into bedrock, karst cave, solution pore, fracture, crack, and fractured zone. Calculate the channel volume of fractures and faults according to the geological section cut longitudinally along the well and in combination with the water invasion path.

[0025] Preferably, the production dynamic data in step (4) includes: water cut, daily liquid production, daily oil production, and historical production curve.

[0026] Preferably, for the relationship curve between the water-oil ratio and the water production increase rate in step (4), select the part with a slope greater than 30°.

[0027] Preferably, the method for calculating the estimated dynamic bottom water invasion volume in step (4) includes the following steps:

[0028] Starting from the continuous water production after the oil well sees water and ending at a water cut of 90%, draw a daily water cut curve, take the continuously rising section, subtract the daily water production of the next day from the daily water production of the previous day, accumulate the increase, define negative numbers as 0, and calculate the fracture volume occupied by the water invasion volume, that is, the estimated dynamic bottom water invasion volume.

[0029] The present invention also provides an application of the above method for determining the water plugging dosage of a fractured reservoir in reservoir water plugging.

[0030] Preferably, the type of the reservoir includes a fractured reservoir.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides a method for calculating the water plugging dosage suitable for fractured reservoirs by using landmark and Petrel software for calculation and analysis on the basis of conventional seismic data and production dynamic data, solving the problem of the lack of a method for calculating the water plugging dosage suitable for fractured reservoirs in the prior art; at the same time, the method provided by the present invention is made on the basis of existing data, improving the utilization rate of existing data. The method can effectively obtain the water plugging volume required during the on-site construction process, improving the efficiency of water plugging and the development efficiency of the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a data graph of the water cut and daily oil production of the corresponding well in the embodiment of the present invention on different dates before and after water plugging. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In this embodiment, the implementation well involved was initially designed with an injection volume of 150 cubic meters using the empirical method on May 20, 2023. After opening the well, it showed high water cut, indicating ineffective water plugging. Based on this, the embodiments of the present invention are as follows:

[0035] Embodiment A method for determining the water plugging dosage of a fractured reservoir

[0036] (1) Based on seismic data inversion, use landmark software to describe the fracture-cavity structure of the single-well reservoir, and clarify the positional relationship between the open-hole section of the wellbore and the fracture and cavity structures;

[0037] (2) According to the positional relationship clarified in step (1), use Petrel software to analyze the t-Navigator data volume to clarify the water invasion path. Specifically:

[0038] Based on the comprehensive understanding of the karst system, use seismic attributes such as coherence, ant body, and tensor to identify static communication channels, use methods such as tracers and well interference to carry out dynamic communication path identification, use the geological data volume model constructed by Petrel software's t-Navigator data volume to simulate streamlines, and finally form a comprehensive water drive path identification method, and clarify the water invasion path according to the formed water drive path identification method.

[0039] (3) Use Petrel software to calculate the volume of the dominant channel of the water invasion path described in step (2); according to field experience, set the porosity to 1%, and the data volume is divided into bedrock, karst cave, solution pore, fracture, crack, and fractured zone. According to the geological section cut along the well longitudinal direction and combined with the water invasion path, calculate the channel volume of the fracture and fracture; this volume is from the part below the wellbore to the oil-water interface.

[0040] (4) Draw the relationship curve between the water-oil ratio and the water production increase rate based on the production performance data (water cut, daily liquid production, daily oil production, and historical production curve). Select the part with a slope greater than 30°. Starting from the continuous water production after the oil well sees water and ending at a water cut of 90%, draw the daily water cut curve. Take the continuously rising section, subtract the daily water production of the next day from the daily water production of the previous day, accumulate the increase amount, define negative numbers as 0, calculate the fracture volume occupied by the water invasion amount, and estimate the dynamic bottom water invasion amount.

[0041] (5) Compare the dynamic bottom water invasion amount with the volume of the dominant channels simulated by the geological model, and take the minimum value of the two as the dosage of the water shutoff agent for the fractured reservoir.

[0042] The following are the positive effects generated by this embodiment

[0043] Through the above embodiment, the volume of the dominant fractures corresponding to the well in the embodiment is finally determined to be 456 m 3 . Considering two short fractures, a two-step approach is designed. First, deep plugging is carried out for production, and then shallow plugging is carried out. The dosage of the plugging agent for the first deep plugging is 235 m 3 , and the dosage of the plugging agent for the second shallow plugging is 221 m 3 .

[0044] The oil production increase results are as Figure 1 shown. On June 23, 2023, the first water shutoff was carried out, with an oil production increase of 3458 t. On September 1, 2023, the second water shutoff was carried out, with a stage oil production increase of 2807.5 t.

[0045] The method provided by the present invention has guided 97 well operations on-site in total, and the efficiency has been increased by 21 percentage points.

[0046] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art does not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for determining the water plugging dosage in a fractured reservoir, characterized in that, It includes the following steps: (1) Based on seismic data inversion, use landmark software to describe the fracture-vug structure of a single-well reservoir, and clarify the positional relationship between the open-hole section of the wellbore and the fracture and vug structures; (2) According to the positional relationship clarified in step (1), use Petrel software to analyze the t-Navigator data volume and clarify the water invasion path; (3) Use Petrel software to calculate the volume of the dominant channel of the water invasion path described in step (2); this volume is from the part below the wellbore to the oil-water interface; (4) Draw a relationship curve between the water-oil ratio and the water production increase rate based on production dynamic data, and calculate the estimated dynamic bottom water invasion volume; (5) By comparing the dynamic bottom water invasion volume with the volume of the dominant channel simulated by the geological model, take the minimum value of the two as the dosage of the water plugging agent for the fractured reservoir.

2. The method according to claim 1, wherein The method for clarifying the water invasion path described in step (2) includes the following steps: ① Identify static connected channels based on seismic attributes; ② On the basis of step ①, carry out the identification of dynamic connected paths, and use Petrel software to simulate streamlines of the t-Navigator data volume, and finally form a comprehensive water flooding path identification method; ③ Clarify the water invasion path according to the water flooding path identification method formed in step ②.

3. The method according to claim 2, wherein The seismic attributes described in step ① include coherence, ant body and tensor.

4. The method according to claim 2, wherein The method for carrying out the identification of dynamic connected paths described in step ② includes using tracers and well interference.

5. The method according to claim 1, characterized in that, The method for using Petrel software to calculate the volume of the dominant channel described in step (3) includes the following steps: Set the porosity to 1%, and divide the data volume into bedrock, karst cave, dissolved pore, fracture, crack, and fractured zone. According to the geological section cut longitudinally along the well, combined with the water invasion path, calculate the channel volume of the fracture and the fault.

6. The method according to claim 1, characterized in that, The production dynamic data described in step (4) includes: water cut, daily liquid production, daily oil production and historical production curves.

7. The method according to claim 1, wherein For the relationship curve between the water-oil ratio and the water production increase rate described in step (4), select the part with a slope greater than 30°.

8. The method according to claim 1, wherein The method for calculating the estimated dynamic bottom water invasion volume described in step (4) includes the following steps: Starting from the continuous water production after the oil well sees water and ending at a water cut of 90%, draw a daily water cut curve, take the continuously rising section, subtract the daily water production of the next day from the daily water production of the previous day, accumulate the increase amount, define negative numbers as 0, and calculate the fracture volume occupied by the water invasion volume, that is, the estimated dynamic bottom water invasion volume.

9. Application of the method according to any one of claims 1-8 in reservoir water plugging.

10. The application according to claim 9, characterized in that, The type of the reservoir includes fractured reservoir.

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