Fluid property identification method based on reservoir anisotropy

Abstract

The invention discloses a fluid property identification method based on reservoir anisotropy, which belongs to the technical field of logging data evaluation and comprises the following steps: S1: obtaining cross-dipole acoustic wave data and three-component induction logging data of a known reservoir, and obtaining fast shear wave time difference, slow shear wave time difference, longitudinal resistivity and transverse resistivity of the reservoir after processing; S2: calculating acoustic wave anisotropy and resistivity anisotropy respectively according to the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity and transverse resistivity information obtained in S1; S3: obtaining a relationship factor between acoustic wave anisotropy and resistivity anisotropy according to S2, and obtaining a relationship between the relationship factor and reservoir fluid properties; S4: identifying the fluid properties of the reservoir to be measured using the relationship factor obtained in step S3, thereby solving the problem of fluid property identification under complex oil and gas reservoir conditions such as low contrast and low resistivity in the prior art and effectively identifying gas and water layers in the reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of well logging data evaluation, and in particular to a fluid property identification method based on reservoir anisotropy. Background Art

[0002] Reservoir fluid property evaluation is the most important task in reservoir evaluation. This evaluation using well logging data is influenced by factors such as reservoir lithology, physical properties, and anisotropy. Reservoir fluid property evaluation has always been a key and challenging area in the field of well logging data evaluation technology. The continuous development of new methods and technologies is crucial for this purpose.

[0003] At present, there are many methods for identifying reservoir fluid properties in the field of logging data evaluation: such as the methods mentioned in the patent "Method for Distinguishing Reservoir Fluid Types Using Resistivity Data (CN101930082B)", the patent "Method for Distinguishing Reservoir Fluid Types by Using the Difference Between Acoustic Porosity and Neutron Porosity (CN101787884B)", the patent "Method for Distinguishing Reservoir Fluid Types by Using the Difference Between Density Porosity and Neutron Porosity (CN101832133B)", and the patent "A Reservoir Fluid Identification Method (CN102913240B)".

[0004] These methods are generally calibrated using regional empirical data and experimental results. However, in some new exploration wells, where there are no corresponding reference results, the accuracy of fluid property identification using these methods is reduced. Furthermore, existing fluid property identification methods are difficult to identify in complex oil and gas reservoir environments, such as low contrast and low resistivity. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for identifying fluid properties based on reservoir anisotropy to solve the limitations and shortcomings of existing methods for identifying reservoir fluid properties using logging data. The method of using three-component induction data and cross-dipole acoustic wave data to identify reservoir fluid properties in this scheme can solve the difficulties of existing technologies in identifying fluid properties under complex oil and gas reservoir conditions such as low contrast and low resistivity.

[0006] Currently, well logging data can be used to evaluate acoustic anisotropy using cross-dipole acoustic data, and resistivity anisotropy using three-component induction data. Reservoir anisotropy can be manifested as: acoustic anisotropy caused by structural anisotropy and resistivity anisotropy caused by fluid distribution. The correlation and difference between the two can be used to evaluate reservoir fluid properties, especially solving the problem of the inability of existing fluid property identification methods to accurately identify gas and water layers in the reservoir.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for identifying fluid properties based on reservoir anisotropy comprises the following steps:

[0009] S1: Obtain cross-dipole acoustic wave data and three-component induction logging data of a known reservoir, and after processing, obtain the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity, and transverse resistivity of the reservoir;

[0010] S2: Calculate the acoustic anisotropy based on the fast shear wave time difference and slow shear wave time difference information obtained in S1; calculate the resistivity anisotropy based on the longitudinal resistivity and transverse resistivity information obtained in S1;

[0011] S3: Based on the acoustic anisotropy and resistivity anisotropy obtained in S2, a relationship factor between the acoustic anisotropy and resistivity anisotropy is obtained, and a relationship between the relationship factor and reservoir fluid properties is obtained;

[0012] S4: Identify the fluid properties of the reservoir to be measured using the relationship factors obtained in step S3.

[0013] Furthermore, in step S2, the method for calculating the acoustic anisotropy includes the following steps:

[0014] a1. Calculate the absolute anisotropy of the acoustic wave based on the fast shear wave time difference and slow shear wave time difference information obtained in step S1. The calculation formula for the absolute anisotropy of the acoustic wave is: ,in is the absolute anisotropy of the sound wave, is the slow shear wave time difference, is the fast shear wave time difference;

[0015] b1. Then calculate the standard anisotropy of the acoustic wave based on the absolute anisotropy of the acoustic wave. The calculation formula for the standard anisotropy of the acoustic wave is: , For the The standard anisotropy of acoustic waves at each depth point; For the Absolute anisotropy of sound waves at each depth point; is the minimum value of absolute anisotropy of acoustic waves within the processing depth segment; It is the maximum value of the absolute anisotropy of the acoustic wave within the processing depth segment.

[0016] Furthermore, in step S2, the method for calculating resistivity anisotropy includes the following steps:

[0017] a2. Calculate the absolute resistivity anisotropy according to the longitudinal resistivity and transverse resistivity information obtained in step S1. The absolute resistivity anisotropy is defined as: , where is the absolute anisotropy of resistivity, is the longitudinal resistivity, is the transverse resistivity;

[0018] b2. The standard anisotropy of resistivity is calculated based on the absolute anisotropy of resistivity in a2. The standard anisotropy of resistivity is defined as: , where For the The standard anisotropy of resistivity at each depth point, For the The absolute anisotropy of resistivity at each depth point, To process the minimum value of absolute resistivity anisotropy within the depth section, is the maximum value of absolute resistivity anisotropy within the processing depth section.

[0019] Furthermore, in step S3, the relationship factor between acoustic anisotropy and resistivity anisotropy is the anisotropic fluid identification factor , The formula is: , >0.

[0020] Furthermore, in step S4, the relationship between the relationship factor and the reservoir fluid properties is: When , the reservoir fluid property is gas-water layer; when When , the reservoir fluid properties are gas layer, water layer or dry layer.

[0021] Furthermore, in step S4, the method for identifying the fluid properties of the reservoir to be measured using the relationship factors includes the following steps:

[0022] a3. Obtain cross-dipole acoustic data and three-component induction logging data of the reservoir to be measured, and after processing, obtain fast shear wave time difference, slow shear wave time difference, longitudinal resistivity and transverse resistivity of the reservoir to be measured;

[0023] b3. Substitute the fast shear wave time difference and slow shear wave time difference information of the reservoir to be measured obtained in step a3 into the formula:

[0024] , Get the reservoir to be tested ANIAS i ＇ Value; Substitute the longitudinal resistivity and transverse resistivity information of the reservoir to be measured obtained in step a3 into the formula: , Get the reservoir to be tested RVHS i ＇ value;

[0025] c3. Calculate the reservoir to be measured δ' , δ' = RVHS i ＇ - ANIAS i ＇ ,according to δ' The value of is used to determine the fluid properties of the reservoir to be tested.

[0026] Furthermore, the fast shear wave time difference and the slow shear wave time difference are information obtained by using the waveform inversion method using cross-dipole acoustic logging data.

[0027] Furthermore, the longitudinal resistivity and the transverse resistivity are information obtained by using three-component induction logging data through a resistivity inversion method.

[0028] Furthermore, the cross-dipole acoustic logging data is obtained by any one of XMAC, WAVESONIC, and SonicScanner instruments.

[0029] Furthermore, the three-component sensing data is obtained by any one of Rt_Scanner, MCI, and 3DIT instruments.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] 1. In the present invention, a new fluid property identification method is adopted to identify the reservoir, which increases the identification method of the reservoir property and broadens the identification scheme of the reservoir property.

[0032] Second, the present invention applies the newer three-component induction logging data and combines it with the more mature cross-dipole acoustic data technology in the existing technology, and then conducts research to provide more effective and stable data information. This method is not easily affected by other logging data and has good independence.

[0033] 3. In the present invention, when this solution is used for fluid identification, independent operations can be performed on the logging data of a single well, and there is no need to establish a unified fluid identification standard based on the logging data of multiple wells. It has broad application prospects in new exploration areas without reference logging data.

[0034] 4. In the present invention, the anisotropic fluid identification factor proposed combines the acoustic field and the electric field to improve the accuracy of reservoir fluid property identification.

[0035] 5. In the present invention, this method is not affected by the survey lithology and reservoir type and has wide practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1This is the fluid property identification result diagram of well A.

[0037] Figure 2 yes Figure 1 Enlarged view of the “conventional logging curve” part.

[0038] Figure 3 yes Figure 1 Enlarged view of the "Acoustic Anisotropy" section.

[0039] Figure 4 yes Figure 1 Enlarged view of the "Electrical Anisotropy" part.

[0040] Figure 5 yes Figure 1 Enlarged view of the "standard anisotropy" part.

[0041] Figure 6 yes Figure 1 Enlarged view of the "fluid identification factor" part. DETAILED DESCRIPTION

[0042] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0043] Example 1

[0044] A method for identifying fluid properties based on reservoir anisotropy, belonging to the technical field of well logging data evaluation, comprises the following steps:

[0045] S1: Obtain cross-dipole acoustic wave data and three-component induction logging data of a known reservoir, and after processing, obtain the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity, and transverse resistivity of the reservoir;

[0046] S2: Calculate the acoustic anisotropy based on the fast shear wave time difference and slow shear wave time difference information obtained in S1; calculate the resistivity anisotropy based on the longitudinal resistivity and transverse resistivity information obtained in S1;

[0047] S3: Based on the acoustic anisotropy and resistivity anisotropy obtained in S2, a relationship factor between the acoustic anisotropy and resistivity anisotropy is obtained, and a relationship between the relationship factor and reservoir fluid properties is obtained;

[0048] S4: Identify the fluid properties of the reservoir to be measured using the relationship factors obtained in step S3.

[0049] This most basic implementation combines the currently mature cross-dipole acoustic wave technology with the newer three-component induction logging technology to identify fluid properties in the target reservoir. This is particularly suitable for new exploration areas where reference logging data is unavailable. Cross-dipole acoustic wave data primarily detects reservoir wall information, while three-component induction logging data primarily detects reservoir wall and fluid information. This combination of technologies yields more accurate reservoir fluid property information than that obtained using existing technologies.

[0050] Example 2

[0051] A method for identifying fluid properties based on reservoir anisotropy comprises the following steps:

[0052] S1: Obtain cross-dipole acoustic wave data and three-component induction logging data of a known reservoir, and after processing, obtain the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity, and transverse resistivity of the reservoir;

[0053] S2: Calculate the acoustic anisotropy based on the fast shear wave time difference and slow shear wave time difference information obtained in S1; calculate the resistivity anisotropy based on the longitudinal resistivity and transverse resistivity information obtained in S1;

[0054] S3: Based on the acoustic anisotropy and resistivity anisotropy obtained in S2, a relationship factor between the acoustic anisotropy and resistivity anisotropy is obtained, and a relationship between the relationship factor and reservoir fluid properties is obtained;

[0055] S4: Identify the fluid properties of the reservoir to be measured using the relationship factors obtained in step S3.

[0056] Furthermore, in step S2, the method for calculating the acoustic anisotropy includes the following steps:

[0057] a1. Calculate the absolute anisotropy of the acoustic wave based on the fast shear wave time difference and slow shear wave time difference information obtained in step S1. The calculation formula for the absolute anisotropy of the acoustic wave is: ,in is the absolute anisotropy of the sound wave, is the slow shear wave time difference, is the fast shear wave time difference;

[0058] b1. Then calculate the standard anisotropy of the acoustic wave based on the absolute anisotropy of the acoustic wave. The calculation formula for the standard anisotropy of the acoustic wave is: , For the The standard anisotropy of acoustic waves at each depth point; For the Absolute anisotropy of sound waves at each depth point; is the minimum value of absolute anisotropy of acoustic waves within the processing depth segment; It is the maximum value of the absolute anisotropy of the acoustic wave within the processing depth segment.

[0059] Furthermore, in step S2, the method for calculating resistivity anisotropy includes the following steps:

[0060] a2. Calculate the absolute resistivity anisotropy according to the longitudinal resistivity and transverse resistivity information obtained in step S1. The absolute resistivity anisotropy is defined as: , where is the absolute anisotropy of resistivity, is the longitudinal resistivity, is the transverse resistivity;

[0061] b2. The standard anisotropy of resistivity is calculated based on the absolute anisotropy of resistivity in a2. The standard anisotropy of resistivity is defined as: , where For the The standard anisotropy of resistivity at each depth point, For the The absolute anisotropy of resistivity at each depth point, To process the minimum value of absolute resistivity anisotropy within the depth section, is the maximum value of absolute resistivity anisotropy within the processing depth section.

[0062] Furthermore, in step S3, the relationship factor between acoustic anisotropy and resistivity anisotropy is the anisotropic fluid identification factor , The formula is: , >0.

[0063] Furthermore, in step S4, the relationship between the relationship factor and the reservoir fluid properties is: When , the reservoir fluid property is gas-water layer; when When , the reservoir fluid properties are gas layer, water layer or dry layer.

[0064] Using the above method, we use an existing actual well (well A, the reservoir information of which is known) as an example to further illustrate this technical solution. The specific operation steps are as follows:

[0065] a3. First, using the aforementioned method, obtain cross-dipole acoustic data and three-component induction logging data from Well A. After processing, the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity, and lateral resistivity of the reservoir to be measured are obtained.

[0066] b3. Substitute the fast shear wave time difference and slow shear wave time difference information of the reservoir to be measured obtained in step a3 into the formula:

[0067] , , and obtain the reservoir to be measured Value; Substitute the longitudinal resistivity and transverse resistivity information of the reservoir to be measured obtained in step a3 into the formula: , , and obtain the reservoir to be measured value;

[0068] c3. Calculate the reservoir to be measured δ , δ = RVHS - ANIAS , the various parameters involved refer to Figure 1 . According to Figure 1 middle δ The value of is used to determine the fluid properties of the reservoir to be tested.

[0069] Reference Attachment Figure 1-6 , Figure 1 This is the fluid property identification result diagram of well A. Figure 2-6 yes Figure 1 Partially enlarged diagrams of “conventional logging curves”, “acoustic anisotropy”, “electrical anisotropy”, “standard anisotropy” and “fluid identification factor”. Figure 6 It can be seen that the 1# reservoir The value is between -0.16 and 0.81. δ The value is higher than 0.2 in some sections, indicating that gas and water coexist in the reservoir, and the comprehensive interpretation is that it is a gas-water layer; δ The value is between -0.45 and 0.36. δ The value is higher than 0.2 in some sections of the well, indicating that the reservoir also contains gas and water layers. The oil test results show that the 1# and 2# reservoirs in the well are indeed gas and water layers, which is consistent with the interpretation results. Therefore, the method is reliable.

[0070] Preferably, the fast shear wave time difference and slow shear wave time difference in this embodiment are information obtained by waveform inversion method using cross-dipole acoustic logging data; preferably, the longitudinal resistivity and transverse resistivity in this embodiment are information obtained by resistivity inversion method using three-component induction logging data.

[0071] Furthermore, the instrument recommended for collecting cross-dipole acoustic wave data is XMAC, and other cross-dipole acoustic wave instruments such as WAVESONIC and SonicScanner that can invert the time difference between fast and slow shear waves can also be used; the instrument recommended for collecting three-component induction data is Rt_Scanner, and other three-component induction instruments such as MCI and 3DIT that can invert the longitudinal and transverse resistivity can also be used.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A fluid property identification method based on reservoir anisotropy, characterized in that: The following steps are involved: S1: Obtain cross-dipole acoustic wave data and three-component induction logging data of a known reservoir, and after processing, obtain the fast shear wave time difference, slow shear wave time difference, longitudinal resistivity, and transverse resistivity of the reservoir; S2: Calculate the acoustic standard anisotropy based on the fast shear wave time difference and slow shear wave time difference information obtained in S1; calculate the resistivity standard anisotropy based on the longitudinal resistivity and transverse resistivity information obtained in S1; S3: Based on the acoustic wave standard anisotropy and resistivity standard anisotropy obtained in S2, a relationship factor between the acoustic wave standard anisotropy and the resistivity standard anisotropy is obtained, and a relationship between the relationship factor and reservoir fluid properties is obtained; In this step, the relationship factor between the acoustic wave standard anisotropy and the resistivity standard anisotropy is the anisotropic fluid identification factor. , The formula is: , >0, where: RVHS represents the standard anisotropy of resistivity, ANIAS represents the standard anisotropy of acoustic waves; S4: Using the relationship factors obtained in step S3 to identify the fluid properties of the reservoir to be measured, In this step, the relationship between the relationship factor and the reservoir fluid properties is: When , the reservoir fluid property is gas-water layer; when When , the reservoir fluid properties are gas layer, water layer or dry layer.

2. The method for identifying fluid properties based on reservoir anisotropy according to claim 1, characterized in that: In step S2, the method for calculating the standard anisotropy of the acoustic wave comprises the following steps: a1. Calculate the absolute anisotropy of the acoustic wave based on the fast shear wave time difference and slow shear wave time difference information obtained in step S1. The calculation formula for the absolute anisotropy of the acoustic wave is: ,in is the absolute anisotropy of the sound wave, is the slow shear wave time difference, is the fast shear wave time difference; b1. Then calculate the standard anisotropy of the acoustic wave based on the absolute anisotropy of the acoustic wave. The calculation formula for the standard anisotropy of the acoustic wave is: , For the The standard anisotropy of acoustic waves at each depth point; For the Absolute anisotropy of sound waves at each depth point; is the minimum value of absolute anisotropy of acoustic waves within the processing depth segment; It is the maximum value of the absolute anisotropy of the acoustic wave within the processing depth segment.

3. The method for identifying fluid properties based on reservoir anisotropy according to claim 2, characterized in that: In step S2, the method for calculating the standard anisotropy of resistivity includes the following steps: a2. Calculate the absolute resistivity anisotropy according to the longitudinal resistivity and transverse resistivity information obtained in step S1. The absolute resistivity anisotropy is defined as: , where is the absolute anisotropy of resistivity, is the longitudinal resistivity, is the transverse resistivity; b2. The standard anisotropy of resistivity is calculated based on the absolute anisotropy of resistivity in a2. The standard anisotropy of resistivity is defined as: , where For the The standard anisotropy of resistivity at each depth point, For the The absolute anisotropy of resistivity at each depth point, To process the minimum value of absolute resistivity anisotropy within the depth section, is the maximum value of absolute resistivity anisotropy within the processing depth section.

4. The method for identifying fluid properties based on reservoir anisotropy according to claim 3, characterized in that: In step S4, the method for identifying the fluid properties of the reservoir to be measured using the relationship factor includes the following steps: a3. Obtain cross-dipole acoustic data and three-component induction logging data of the reservoir to be measured, and after processing, obtain fast shear wave time difference, slow shear wave time difference, longitudinal resistivity and transverse resistivity of the reservoir to be measured; b3. Substitute the fast shear wave time difference and slow shear wave time difference information of the reservoir to be measured obtained in step a3 into the formula: , Get the reservoir to be tested ANIAS i ＇ Value; Substitute the longitudinal resistivity and transverse resistivity information of the reservoir to be measured obtained in step a3 into the formula: , Get the reservoir to be tested RVHS i ＇ value; c3. Calculate the reservoir to be measured , ,according to The value of is used to determine the fluid properties of the reservoir to be tested.

5. The method for identifying fluid properties based on reservoir anisotropy according to any one of claims 1 to 4, characterized in that: The fast shear wave time difference and the slow shear wave time difference are information obtained by using the waveform inversion method using cross-dipole acoustic logging data.

6. The method for identifying fluid properties based on reservoir anisotropy according to any one of claims 1 to 4, characterized in that: The longitudinal resistivity and the transverse resistivity are information obtained by using three-component induction logging data through a resistivity inversion method.

7. The method for identifying fluid properties based on reservoir anisotropy according to claim 5, characterized in that: The cross-dipole acoustic logging data is obtained by using any one of the instruments including XMAC, WAVESONIC and SonicScanner.

8. The method for identifying fluid properties based on reservoir anisotropy according to claim 6, characterized in that: The three-component sensing data is obtained by any one of the instruments Rt_Scanner, MCI, and 3DIT.

Images