Ultra-low / ultra-low permeability reservoir blockage determination method based on sidetrack coring technology

Abstract

The invention discloses an ultra-low / ultra-low permeability reservoir blockage determination method based on a sidetrack coring technology. The method comprises the following steps that 1, a rock core sample at a preset position is obtained; 2, recording and numbering the positions of the rock core samples; 3, the permeability and porosity of the obtained rock core samples are measured respectively, the permeability and porosity damage degree of each rock core is calculated according to the original permeability and porosity of a reservoir, and the permeability damage and the horizontal distance from the rock core to a shaft and the porosity damage and the horizontal distance from the rock core to the shaft are calculated; and 4, determining the damage space distribution condition of the rock core sample according to the data of the permeability damage degree and the porosity damage degree obtained in the step 3, and completing the determination of the blockage position of the permeability reservoir. The invention belongs to the technical field of oilfield development and detection, and solves the problems that a reservoir damage analysis method in the prior art is relatively large in limitation, cannot accurately reflect the pore damage phenomenon of an ultra-low / ultra-low permeability reservoir, cannot directly carry out experimental analysis from the microscopic level of the reservoir, and is difficult to measure the damage degree of the pore level of the reservoir.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development and exploration technology, and relates to a method for determining the blockage of ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology. Background Technology

[0002] Globally, low-permeability reservoirs are abundant and important, with a wide distribution. my country is one country with relatively rich low-permeability oil and gas reserves, and in my country's low-permeability oilfields, ultra-low permeability and extra-low permeability reservoirs account for more than half of the total low-permeability reserves. With the gradual increase in my country's demand for oil and gas resources, ultra-low / extra-low permeability oil and gas reservoirs have become a focus of my country's oil and gas development. However, due to the narrow pore throats and dense lithology of ultra-low / extra-low permeability reservoirs, they are highly susceptible to plugging damage during development, severely impacting reservoir development. Therefore, clarifying the mechanism of reservoir plugging damage is crucial for adopting corresponding unblocking measures and improving reservoir development efficiency.

[0003] Current laboratory research on plugging damage analysis methods is extensive, focusing primarily on conventional reservoirs. This overly simplistic approach limits the application of existing methods to ultra-low / ultra-low permeability reservoirs. Firstly, ultra-low / ultra-low permeability reservoirs are characterized by dense lithology, high cement content, complex mineral composition, and intricate pore structures, significantly increasing the difficulty of describing and analyzing reservoir properties. Conventional core analysis methods cannot accurately obtain reservoir damage information. Secondly, ultra-low / ultra-low permeability reservoirs generally exhibit poor physical properties, extremely low permeability, and pronounced non-Darcy flow characteristics, making it difficult for conventional core flow experiments to effectively simulate the actual flow conditions within the reservoir, thus hindering effective damage mechanism research.

[0004] Therefore, existing technologies, based on single experimental results, often deviate significantly from the actual situation and cannot accurately reflect the degree of damage to the reservoir. There is an urgent need to develop new comprehensive methods that employ advanced and precise technical means, which is of great significance for the study of the plugging mechanism of ultra-low / ultra-low permeability reservoirs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the blockage of ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology. This method solves the problems of existing reservoir damage analysis methods having significant limitations, failing to accurately reflect the pore damage phenomenon in ultra-low / ultra-low permeability reservoirs, being unable to conduct direct experimental analysis at the microscopic level of the reservoir, and having difficulty in determining the degree of damage at the pore level.

[0006] The technical solution adopted in this invention is a method for determining the blockage of ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology, implemented according to the following steps: Step 1: Obtain core samples from predetermined locations; Step 2: Record the location of the core samples and number them; Step 3: Measure the permeability and porosity of the obtained core samples respectively, and compare them with the original permeability and porosity of the reservoir. Calculate the degree of permeability and porosity damage of each core sample, and calculate the permeability damage and horizontal distance from the wellbore, and the porosity damage and horizontal distance from the wellbore. Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil reservoir.

[0007] The beneficial effects of this invention are that the flexible drill pipe side-drilling coring technology involves less engineering work and has lower costs. It can achieve the acquisition of deep oil reservoir cores at fixed points and orientations, and the obtained reservoir cores can truly reflect the characteristics of the blocked formation. This research method can be used to study the spatial distribution of reservoir damage, clarify the damage patterns of ultra-low / ultra-low permeability reservoirs under different development conditions, and provide a more comprehensive and detailed data reference for guiding oilfield development. Attached Figure Description

[0008] Figure 1 This is the curve of core horizontal displacement versus permeability damage obtained in Example 1 of the method of the present invention; Figure 2 This is the curve of core horizontal displacement versus porosity damage obtained in Example 1 of the method of the present invention. Detailed Implementation

[0009] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0010] The principle of this invention, a method for determining blockage in ultra-low / ultra-low permeability reservoirs based on sidetracking coring technology, is as follows: First, a flexible drill string is used to achieve ultra-short radius horizontal drilling, and coring is performed at fixed points and orientations in the deep oil layer to obtain reservoir-damaged core samples. Then, the obtained reservoir core samples are numbered and labeled according to the drill string footage parameters during coring, clarifying their horizontal distance from the wellbore. Next, permeability and porosity tests are conducted on the core samples, and these are compared with the permeability and porosity of the original reservoir core to determine the degree of damage. Finally, based on the spatial distance of the core sample from the wellbore in the reservoir, a spatial distribution map of core damage based on permeability and porosity damage and distance from the wellbore is plotted to understand the degree of damage to the reservoir in the space surrounding the wellbore.

[0011] This invention relates to a method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology, implemented according to the following steps: Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0012] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) In the formula: D k The degree of damage to core permeability. k is the original permeability of the reservoir, mD; k i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) In the formula: D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0013] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0014] Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil-permeable reservoir. The specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the permeability and porosity damage levels of each core sample as the ordinates, a spatial distribution curve (or spatial distribution map of reservoir core damage) was plotted for each core sample. See [link to relevant documentation]. Figure 1 , Figure 2 As shown.

[0015] Example 1 The following steps are performed according to the aforementioned method for determining plugging in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology: Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0016] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) In the formula: D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) In the formula: D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0017] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0018] Step 4: Based on the data on permeability and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core samples and complete the determination of the blockage location in the seepage reservoir. Specifically, plot the spatial distribution curve of damage for each core sample by using the horizontal displacement distance from the wellbore as the abscissa and the data on the permeability and porosity damage as the ordinate. (See attached diagram). Figure 1 and Figure 2 As shown.

[0019] Example 2 Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0020] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0021] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0022] Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil-permeable reservoir. The specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the data on the permeability damage degree and porosity damage degree of each core sample as the ordinate, the damage spatial distribution curve of each core sample was plotted.

[0023] Example 3 Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0024] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0025] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0026] Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil-permeable reservoir. The specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the data on the permeability damage degree and porosity damage degree of each core sample as the ordinate, the damage spatial distribution curve of each core sample was plotted.

[0027] Example 4 Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0028] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) DΦ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0029] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0030] Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil-permeable reservoir. The specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the data on the permeability damage degree and porosity damage degree of each core sample as the ordinate, the damage spatial distribution curve of each core sample was plotted.

[0031] Example 5 Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0032] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0033] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0034] Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil-permeable reservoir. The specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the data on the permeability damage degree and porosity damage degree of each core sample as the ordinate, the damage spatial distribution curve of each core sample was plotted.

[0035] Example 6 Step 1: Obtain core samples from predetermined locations; Based on the coring scheme, the reservoir flexible drill pipe side drilling coring operation was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the coring well; Step 2: Record the location of the core samples and number them; For each core sample obtained, its horizontal displacement from the wellbore was recorded and numbered from closest to furthest from the wellbore. When numbering, the wellbore was used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the wellbore when obtaining the core was used as the horizontal displacement coordinate of that core. Step 3: Measure the permeability and porosity of the obtained core samples, and compare them with the original permeability and porosity of the reservoir (e.g., the original permeability of the reservoir is 2.41 mD, and the original porosity is 12.4%, which is the actual measured data), and calculate the degree of permeability and porosity damage of each core sample; for specific experimental procedures, refer to the requirements of the standard "SY / T 5336-2006 Core Analysis Methods".

[0036] 3.1) Based on the measured core permeability and core permeability damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core permeability and displacement distance, and the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: (1) D k The degree of damage to core permeability is given by k, where k is the original reservoir permeability in mD; i The core permeability is expressed in mD. 3.2) Based on the measured core porosity and core porosity damage data, and the horizontal displacement distance coordinates of the core, establish the relationship between core porosity and displacement distance, as well as the relationship between core porosity damage and displacement distance. The formula for calculating the degree of core porosity damage is as follows: (2) D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

[0037] 3.3) The relationship between core permeability damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore. 3.4) The relationship between core porosity damage and horizontal distance from the wellbore is obtained as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

[0038] Step 4: Based on the data on the degree of permeability damage and the degree of porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the seepage reservoir. The specific process is as follows: use the horizontal displacement distance of each core sample from the wellbore as the abscissa, and use the data on the degree of permeability damage and the degree of porosity damage of each core sample as the ordinate to draw the spatial distribution curve of damage for each core sample.

Claims

1. A method for determining plugging in ultra-low / ultra-low permeability reservoirs based on sidetracking coring technology, characterized in that, Follow these steps: Step 1: Obtain core samples from predetermined locations; Step 2: Record the location of the core samples and number them; Step 3: Measure the permeability and porosity of the obtained core samples respectively, and compare them with the original permeability and porosity of the reservoir. Calculate the degree of permeability and porosity damage of each core sample, and calculate the permeability damage and horizontal distance from the wellbore, and the porosity damage and horizontal distance from the wellbore. Step 4: Based on the data on the degree of permeability damage and porosity damage obtained in Step 3, determine the spatial distribution of damage in the core sample and complete the determination of the blockage location in the oil reservoir.

2. The method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, In step 1, the specific process is as follows: Based on the coring scheme, the reservoir flexible drill pipe side drilling coring was carried out to achieve ultra-short radius horizontal drilling, realize fixed-point and fixed-azimuth coring work, and obtain core samples from the predetermined positions in the wellbore of the cored well.

3. The method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, Step 2, the specific process is as follows: For each core sample obtained, its horizontal displacement from the wellbore was recorded, and the samples were numbered from closest to furthest from the wellbore. When numbering, the core well casing is used as the reference origin for the horizontal displacement of the core, and the horizontal displacement of the section closer to the casing when obtaining the core is used as the horizontal displacement coordinate of the core.

4. The method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, In step 3, Based on the measured core permeability and permeability damage data, and the horizontal displacement coordinates of the core, formulas are established for the relationship between core permeability and displacement distance, as well as the relationship between core permeability damage and displacement distance. The formula for calculating the degree of core permeability damage is as follows: （1） In the formula: D k The degree of damage to core permeability. k is the original permeability of the reservoir, mD; k i The permeability of the core sample is expressed in mD.

5. The method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, In step 3, Based on the measured core porosity and porosity damage data, and the horizontal displacement coordinates of the core, formulas are established to relate core porosity to displacement distance and core porosity damage to displacement distance. The formula for calculating the degree of core porosity damage is as follows: （2） In the formula: D Φ The degree of damage to core porosity; Φ represents the original porosity of the reservoir, %; Φ i The porosity of the core sample is %.

6. The method for determining plugging in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, In step 3, The relationship between core permeability damage and horizontal distance from the wellbore is as follows: x This refers to the horizontal distance between the core sample and the wellbore.

7. The method for determining plugging in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, In step 3, The relationship between core permeability damage and horizontal distance from the wellbore is as follows: , x This refers to the horizontal distance between the core sample and the wellbore.

8. The method for determining blockage in ultra-low / ultra-low permeability reservoirs based on side-drilling coring technology according to claim 1, characterized in that, Step 4, the specific process is as follows: Using the horizontal displacement distance of each core sample from the wellbore as the abscissa, and the data on the permeability damage degree and porosity damage degree of each core sample as the ordinate, the damage spatial distribution curve of each core sample was plotted.

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