A method for determining the contamination level near the wellbore based on the skin factor of thermodynamic parameters.

Abstract

This invention relates to a method for determining the contamination level near a wellbore based on a skin factor derived from thermodynamic parameters. The method includes: measuring wellbore parameters and thermodynamic parameters; establishing a pressure relationship equation near the wellbore based on the wellbore parameters and thermodynamic parameters; establishing a temperature relationship equation near the wellbore based on the wellbore parameters and thermodynamic parameters; solving for the skin factor based on the pressure and temperature relationship equations; and determining the contamination level near the wellbore based on the skin factor. This invention can quickly calculate the skin factor from a thermodynamic perspective when the thermodynamic parameters are known, without the need for fitting well test curves, thus improving the efficiency of well test interpretation to a certain extent. The calculation steps are simple and the method is fast.

Description

Technical Field

[0001] This invention relates to the field of well testing technology, specifically to a method for determining the degree of contamination near the wellbore based on the skin factor of thermodynamic parameters. Background Technology

[0002] Due to imperfect perforation opening during drilling, contamination occurs near the wellbore, and the degree of contamination is usually expressed as the skin factor. Within the contaminated zone, the permeability near the wellbore changes due to the skin factor, and similarly, thermodynamic parameters (such as thermal conductivity) are also affected. Currently, pressure recovery testing is a common method for calculating the skin factor, and establishing the relationship between the skin factor and thermodynamic parameters could be a new approach to calculating the skin factor.

[0003] The skin factor is often used as a basis for deciding whether to implement production enhancement measures to increase the productivity of a single well. Determining the skin factor is crucial to ensuring the normal production of oil wells. Calculating the skin factor from a thermodynamic perspective eliminates the need for well test curve fitting, thus improving well test interpretation efficiency to some extent. Combining well test interpretation with calculations can also make the skin factor calculation results more accurate. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a method for determining the contamination level near the wellbore based on the skin factor using thermodynamic parameters, thereby solving problems related to the interpretation and calculation of the skin factor.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for determining the contamination level near a wellbore based on a skin factor derived from thermodynamic parameters includes:

[0007] Measure wellbore parameters and thermodynamic parameters;

[0008] Based on the wellbore parameters and the thermodynamic parameters, establish the pressure relationship equation near the wellbore;

[0009] Based on the wellbore parameters and the thermodynamic parameters, establish an equation relating the temperature near the wellbore.

[0010] The skin factor is solved based on the pressure and temperature equations, and the contamination level near the wellbore is determined based on the skin factor.

[0011] Wellbore parameters include at least one of the following groups of references: wellbore radius, tubing inner diameter, tubing outer diameter, casing inner diameter, and casing outer diameter.

[0012] Thermodynamic parameters include at least one of the following references: annular thermal conductivity, cement annular thermal conductivity, and formation thermal conductivity.

[0013] Based on the wellbore parameters and the thermodynamic parameters, the pressure relationship equation near the wellbore is established as follows:

[0014] (1)

[0015] in, Indicates the bottom hole pressure, in Pa; represents the radius of the wellbore, m; This refers to epidermal factors, which are dimensionless. Indicates pressure, Indicates the radius.

[0016] The equations relating temperature near the wellbore, based on the wellbore parameters and the thermodynamic parameters, include:

[0017] Calculate the heat flux per unit length of the wellbore:

[0018] (2)

[0019] According to Ramey and Willhite, the combined thermal conductivity is defined as follows:

[0020] (3)

[0021] Considering the effect of skin factor on effective well diameter, calculate the overall thermal conductivity between the wellbore and formation during tubing production:

[0022] (4)

[0023] Calculate the combined thermal conductivity between the wellbore and the formation during casing production:

[0024] (5)

[0025] Combining equations (2) and (3), the temperature relationship near the wellbore is obtained as follows:

[0026] (6)

[0027] In the formula, Indicates the bottom hole temperature, in K; represents the radius of the wellbore, m; Indicates the inner diameter of the oil pipe, in meters (m). Indicates the outer diameter of the oil pipe, in meters (m). Indicates the inner diameter of the casing, in meters (m). Indicates the outer diameter of the casing, in meters (m). This refers to epidermal factors, which are dimensionless. This represents the thermal conductivity of the formation, expressed in W / (m·K). The value represents the thermal conductivity of the annulus, W / (m·K); The value represents the thermal conductivity of the cement ring, expressed in W / (m·K). This represents the overall thermal conductivity between the wellbore and the formation, expressed in w / (m²·K). This represents heat flux, in w / m³. 2 ; Indicates temperature; Indicates the radius.

[0028] Solving for the skin factor based on the pressure equation and the temperature equation includes:

[0029] Based on equations (1) and (6), we can obtain

[0030] (7)

[0031] The Joule-Thomson coefficient is defined as follows:

[0032] (8)

[0033] In the formula, This represents the Joule-Thomson coefficient, expressed in K / Pa.

[0034] Therefore, equation (5) can be written as

[0035] (9)

[0036] Epidermal factors can be represented as

[0037] (10)

[0038] Substituting equations (4) and (5) into equation (10) respectively, we obtain the expression for the epidermal factor:

[0039] During tubing production, the skin factor expression is:

[0040] (11)

[0041] During casing production, the skin factor expression is:

[0042] (12).

[0043] The present invention has the following advantages due to the adoption of the above technical solutions:

[0044] This invention can quickly calculate the skin factor from a thermodynamic perspective when the thermodynamic parameters are known, without the need for fitting well test curves, which improves the efficiency of well test interpretation to a certain extent. The calculation steps are simple and the method is fast. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0046] Figure 1 It is a wellbore-formation coupling physical model.

[0047] The markings in the attached diagram are as follows:

[0048] 1. Oil pipe

[0049] 2 casings

[0050] 3 Cement ring

[0051] 4. Stratigraphy Detailed Implementation

[0052] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0053] Example 1

[0054] A method for determining the contamination level near a wellbore based on a skin factor derived from thermodynamic parameters includes:

[0055] S1: Collect the basic parameters required for the calculation.

[0056] S2: Establish the pressure and temperature relationship equations near the wellbore.

[0057] S3: Solve for the expression of the epidermal factor based on the established equation.

[0058] Step S1 is as follows:

[0059] Collect the basic parameters required for calculation, including wellbore parameters such as wellbore radius, tubing inner diameter, tubing outer diameter, casing inner diameter, and casing outer diameter; and thermodynamic parameters such as annular thermal conductivity, cement sheath thermal conductivity, and formation thermal conductivity.

[0060] Step S2 is as follows:

[0061] The pressure relationship near the wellbore considering the skin effect is as follows:

[0062] (1)

[0063] The heat flux per unit length of the wellbore (integrated along the circumference of the wellbore) is:

[0064] (2)

[0065] According to the combined thermal conductivity defined by Ramey and Willhite,

[0066] (3)

[0067] Considering the impact of skin factor on effective well diameter, during tubing production

[0068] (4)

[0069] During casing production

[0070] (5)

[0071] Combining equations (2) and (3), the temperature relationship near the wellbore is obtained as follows:

[0072] (6)

[0073] In the formula, Indicates the bottom hole pressure, in Pa; Indicates the bottom hole temperature, in K; represents the radius of the wellbore, m; Indicates the inner diameter of the oil pipe, in meters (m). Indicates the outer diameter of the oil pipe, in meters (m). Indicates the inner diameter of the casing, in meters (m). Indicates the outer diameter of the casing, in meters (m). This refers to epidermal factors, which are dimensionless. This represents the thermal conductivity of the formation, expressed in W / (m·K). The value represents the thermal conductivity of the annulus, W / (m·K); The value represents the thermal conductivity of the cement ring, expressed in W / (m·K). This represents the overall thermal conductivity between the wellbore and the formation, expressed in w / (m²·K). This represents heat flux, in w / m³. 2 .

[0074] Step S3 is as follows:

[0075] According to equations (1) and (6), we can obtain

[0076] (7)

[0077] The Joule-Thomson coefficient is defined as follows:

[0078] (8)

[0079] In the formula, This represents the Joule-Thomson coefficient, in K / Pa.

[0080] Therefore, equation (5) can be written as

[0081] (9)

[0082] Epidermal factors can be represented as

[0083] (10)

[0084] Substituting equations (4) and (5) into equation (10) respectively, we can obtain the expression for the epidermal factor:

[0085] During tubing production, the skin factor expression is:

[0086] (11)

[0087] During casing production, the skin factor expression is:

[0088] (12)

[0089] Figure 1 The wellbore-formation coupling physical model is shown, which shows tubing 1, casing 2, cement sheath 3, and formation 4.

[0090] collect Figure 1 The basic parameters of the display device are shown in Table 1:

[0091] Table 1 Basic Data Table

[0092]

[0093] Calculate the epidermal factor based on the data in Table 1.

[0094]

[0095] The well is being produced using casing, and the skin factor can be calculated to be 0.77 based on the skin factor expression.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the contamination level near a wellbore based on a skin factor using thermodynamic parameters, characterized in that, include: Measure wellbore parameters and thermodynamic parameters; Based on the wellbore parameters and the thermodynamic parameters, establish the pressure relationship equation near the wellbore; Based on the wellbore parameters and the thermodynamic parameters, establish an equation relating the temperature near the wellbore. The skin factor is solved based on the pressure relationship equation and the temperature relationship equation, and the contamination level near the wellbore is determined based on the skin factor; Based on the wellbore parameters and the thermodynamic parameters, the pressure relationship equation near the wellbore is established as follows: (1) in, Indicates the bottom hole pressure, in Pa; represents the radius of the wellbore, m; This refers to epidermal factors, which are dimensionless. Indicates pressure, Indicates radius; The equations relating temperature near the wellbore, based on the wellbore parameters and the thermodynamic parameters, include: Calculate the heat flux per unit length of the wellbore: (2) According to Remy and Wilhelm, the overall thermal conductivity coefficient is defined as follows: (3) Considering the effect of skin factor on effective well diameter, calculate the overall thermal conductivity between the wellbore and formation during tubing production: (4) Calculate the combined thermal conductivity between the wellbore and the formation during casing production: (5) Combining equations (2) and (3), the temperature relationship near the wellbore is obtained as follows: (6) In the formula, Indicates the bottom hole temperature, in K; represents the radius of the wellbore, m; Indicates the inner diameter of the oil pipe, in meters (m). Indicates the outer diameter of the oil pipe, in meters (m). Indicates the inner diameter of the casing, in meters (m). Indicates the outer diameter of the casing, in meters (m). This refers to epidermal factors, which are dimensionless. This represents the thermal conductivity of the formation, expressed in W / (m·K). The value represents the thermal conductivity of the annulus, W / (m·K); The value represents the thermal conductivity of the cement ring, expressed in W / (m·K). This represents the overall thermal conductivity between the wellbore and the formation, expressed in w / (m²·K). This represents heat flux, in w / m³. 2 ; Indicates temperature; Indicates radius; Solving for the skin factor based on the pressure equation and the temperature equation includes: Based on equations (1) and (6), we can obtain (7) The Joule-Thomson coefficient is defined as follows: (8) In the formula, This represents the Joule-Thomson coefficient, expressed in K / Pa. Therefore, equation (5) can be written as (9) Epidermal factors can be represented as (10) Substituting equations (4) and (5) into equation (10) respectively, we obtain the expression for the epidermal factor: During tubing production, the skin factor expression is: (11) During casing production, the skin factor expression is: (12)。 2. The method for determining the contamination level near the wellbore based on the skin factor according to thermodynamic parameters as described in claim 1, characterized in that, The wellbore parameters include at least one of the following references: wellbore radius, tubing inner diameter, tubing outer diameter, casing inner diameter, and casing outer diameter.

3. The method for determining the contamination level near the wellbore based on the skin factor according to thermodynamic parameters as described in claim 1, characterized in that, The thermodynamic parameters include at least one of the following references: annular thermal conductivity, cement annular thermal conductivity, and formation thermal conductivity.

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