A method of evaluating properties of a formation fluid

Abstract

This invention provides a method for evaluating formation fluid properties, comprising the following steps: S1, obtaining multiple samples from different layers within a predetermined area and extracting the peak area of ​​each component peak; S2, collecting oil testing data from each layer within the predetermined area and establishing a corresponding summary table of pyrolysis gas chromatographic component peak areas; S3, calculating the component distortion coefficients of each sample based on the summary table; S4, establishing a reservoir water-cutting indicator chart based on the distortion coefficients; S5, calculating the component distortion coefficient Kz value of the sample from the well to be evaluated; S6, plotting the component distortion coefficient Kz value of the sample from the well to be evaluated onto the reservoir water-cutting indicator chart to determine the water-cutting of the well to be evaluated. This method establishes a reservoir water-cutting indicator chart based on the calculated component distortion coefficient Kz, enabling an objective and accurate evaluation of the water-cutting of the formation in the well to be evaluated.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration geochemistry, and more specifically to a method for evaluating formation fluid properties using the pyrolysis component distortion coefficient. Background Technology

[0002] Well logging technology is the most fundamental technology in oil and gas exploration and development activities. It is the most timely and direct means of discovering and evaluating oil and gas reservoirs, characterized by timely and diverse acquisition of subsurface information and rapid analysis and interpretation. Evaluation well logging techniques mainly include pyrolysis analysis and pyrolysis gas chromatography. The former is an important parameter for evaluating the oil abundance of a formation, while the latter, due to its wider carbon number detection range, obtains more parameters and can reflect changes in formation fluid properties from multiple perspectives, especially in assessing the degree of secondary alteration of crude oil. Its effect on evaluating water content through peak shape changes is particularly significant. However, peak shape changes are affected by many factors, making the subjective opinions of interpreters highly susceptible to influencing the accuracy of the evaluation.

[0003] Therefore, systematically analyzing the peak parameters of each component and establishing a quantitative index to reflect changes in peak shape, while forming a new standard and evaluation method for fluid property identification, is of great significance for improving the accuracy of oil and gas display interpretation and assisting oilfield exploration and development. Summary of the Invention

[0004] The purpose of this invention is to provide a method for evaluating formation fluid properties to solve the aforementioned problems in the prior art. This method involves summing and calculating the ratios of the peak areas of the corresponding pyrolysis gas chromatographic components. Based on the calculated component distortion coefficient Kz and regional oil testing data, points are plotted on a chart according to the derived parameters of the pyrolysis chromatography of the well to be evaluated, thereby evaluating the water-bearing capacity of the formation.

[0005] According to the present invention, a method for evaluating formation fluid properties is provided, comprising the following steps:

[0006] S1, obtain multiple samples from different layers within the predetermined area, and extract the peak area of ​​each component peak in the pyrolysis gas chromatography parameters of the multiple samples;

[0007] S2, collect oil test data for each layer within the predetermined area, determine the fluid properties of multiple samples based on the oil test data, and use the peak area obtained in step S1 to establish a corresponding summary table of pyrolysis gas chromatography component peak areas for different fluid properties.

[0008] S3. Calculate the component distortion coefficients for each of the multiple samples based on the summary table of peak areas in pyrolysis gas chromatography. The formula for calculating the component distortion coefficients is as follows:

[0009]

[0010] Where Kz is the component distortion coefficient, in dimensionless form; C max Carbon area of ​​the main peak, unit: uV.s; ∑C18 - The sum of the peak areas before C18, in µV·s;

[0011] S4. A reservoir water content indicator board is established with the component distortion coefficient Kz value of each of the multiple samples as the abscissa and the sample number of the multiple samples as the ordinate. The reservoir water content indicator board is divided into different regions along the ordinate based on the water content of the fluid properties to which the multiple samples belong.

[0012] S5, obtain the peak area of ​​each component in the pyrolysis gas chromatography parameters of the sample from the well to be evaluated, establish a summary table of the peak areas of the pyrolysis gas chromatography components of the well to be evaluated, and calculate the component distortion coefficient Kz value of the sample from the well to be evaluated; and

[0013] S6. Plot the component distortion coefficient Kz value of the sample from the well to be evaluated onto the reservoir water-cut indicator chart to determine the water-cut of the well to be evaluated.

[0014] According to one embodiment of the present invention, the summary table of peak areas of pyrolysis gas chromatographic components in step S2 includes:

[0015] Table 1 summarizes the peak areas of components from the gas chromatography of oil layer pyrolysis.

[0016] Table 2. Summary of peak areas of components in gas chromatography of oil-water co-layer pyrolysis;

[0017] Table 3 summarizes the peak areas of components from the gas chromatography analysis of oil-bearing aqueous layer pyrolysis; and

[0018] Table 4 summarizes the peak areas of components from aqueous pyrolysis gas chromatography.

[0019] According to one embodiment of the present invention, the reservoir water content indicator board is divided into oil zone, weak water content zone, strong water content zone and water zone from top to bottom along the vertical axis based on the water content of the fluid properties of multiple samples.

[0020] According to one embodiment of the present invention, the method further includes:

[0021] S7. Calculate the dominant peak area of ​​each heavy component in multiple samples according to the following formula:

[0022]

[0023] Among them, C h The area of ​​the dominant peak of the heavy component is expressed in μV·s; nC26…nC33 represents the peak area of ​​the corresponding carbon group component, expressed in μV·s; G: sample weight, expressed in mg; 100: standard substance sample weight, expressed in mg.

[0024] S8, with the component distortion coefficient Kz value of each of the multiple samples as the abscissa and the dominant peak area C of the heavy component as the ordinate. h The values ​​are used as the ordinate to create a component distortion coefficient evaluation chart;

[0025] S9, Calculate the dominant peak area C of the heavy components in the sample from the well to be evaluated. h Value; and

[0026] S10, the component distortion coefficient Kz value and the dominant peak area C of the heavy component in the well to be evaluated. h The values ​​are plotted on the component distortion coefficient evaluation chart to determine the formation fluid properties of the well to be evaluated.

[0027] According to one embodiment of the present invention, step S1 includes: calculating and processing the component peaks of the pyrolysis gas chromatography of multiple samples using a normalization method.

[0028] According to one embodiment of the present invention, components that cannot be identified in the pyrolysis gas chromatography of multiple samples do not participate in ∑C18. - The calculation.

[0029] Because of the above technical solution, the method for evaluating formation fluid properties according to the present invention can accurately evaluate formation fluid properties using pyrolysis and pyrolysis gas chromatography analysis techniques. Based on the peak shape and parameters, interpreters can quickly determine the formation's water content. A component distortion coefficient Kz is established to reflect the degree of secondary alteration of crude oil and the change in peak shape after alteration, reducing subjective differences in human judgment and leading to correct interpretation conclusions, thus solving the problem of difficulty in water content identification. Based on the dominant peak area C of the aforementioned heavy components... h A component distortion coefficient evaluation chart is established to quickly determine the formation fluid properties of the well to be evaluated. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a flowchart of a method for evaluating formation fluid properties according to an embodiment of the present invention;

[0032] Figure 2 This is a flowchart of a method for evaluating formation fluid properties according to another embodiment of the present invention;

[0033] Figure 3 Table 1 shows a summary table of peak areas of gas chromatographic components from oil layer pyrolysis according to an embodiment of the present invention;

[0034] Figure 4Table 2 shows a summary table of peak areas of components from oil-water co-layer pyrolysis gas chromatography according to an embodiment of the present invention;

[0035] Figure 5 Table 3 shows a summary table of peak areas of components in the gas chromatography of oil-containing aqueous layer pyrolysis according to an embodiment of the present invention;

[0036] Figure 6 Table 4 shows a summary table of peak areas of gas chromatographic components from aqueous pyrolysis according to an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of a reservoir water content indicator panel according to an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of a component distortion coefficient evaluation chart according to an embodiment of the present invention;

[0039] Figure 9 A summary table of pyrolysis gas chromatographic component peak areas of a well to be evaluated according to an embodiment of the present invention is shown;

[0040] Figure 10 A summary table of pyrolysis gas chromatographic component peak areas of a well to be evaluated according to another embodiment of the present invention is shown;

[0041] Figure 11 It is a schematic diagram of a reservoir water content indicator board that includes the well deployment points to be evaluated;

[0042] Figure 12 It is a schematic diagram of the component distortion coefficient evaluation chart containing the well drop points to be evaluated. Detailed Implementation

[0043] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0044] Figure 1 This is a flowchart of a method for evaluating formation fluid properties according to an embodiment of the present invention. The method generally includes the following steps:

[0045] S1. Multiple samples are obtained from different layers within a predetermined region, and the peak area of ​​each component peak in the pyrolysis gas chromatography parameters of the multiple samples is extracted. Specifically, the predetermined region can be a certain zone where the well to be evaluated is located. For example, multiple samples are obtained from wells that have already been tested within this zone, and their respective pyrolysis gas chromatograms are obtained to facilitate the collection of testing data for each sample. Preferably, a normalization method can be used to calculate and process the component peaks of the pyrolysis gas chromatograms of the multiple samples.

[0046] S2, collect oil test data for each layer within the predetermined area, determine the fluid properties of multiple samples based on the oil test data, and use the peak area obtained in step S1 to establish a corresponding summary table of pyrolysis gas chromatography component peak areas for different fluid properties. For example, the water content of multiple samples can be determined based on the oil test data and classified into corresponding categories of fluid properties. The peak areas of pyrolysis gas chromatography components of the samples corresponding to each category of fluid properties can be compiled to obtain multiple summary tables.

[0047] S3. Calculate the component distortion coefficients for each of the multiple samples based on the summary table of peak areas of pyrolysis gas chromatography components. The formula for calculating the component distortion coefficients is as follows.

[0048]

[0049] Where Kz is the component distortion coefficient, in dimensionless form; C max Carbon area of ​​the main peak, unit: uV.s; ∑C18 - This is the sum of the peak areas before C18, in µV·s. Specifically, components that cannot be identified in the pyrolysis gas chromatography of multiple samples may be excluded from ∑C18. - The calculation.

[0050] S4. A reservoir water content indicator board is established with the component distortion coefficient Kz value of each of the multiple samples as the x-axis and the sample number of the multiple samples as the y-axis. The reservoir water content indicator board is divided into different regions along the y-axis based on the water content of the fluid properties to which the multiple samples belong.

[0051] S5. Obtain the peak area of ​​each component peak in the pyrolysis gas chromatography parameters of the sample of the well to be evaluated, establish a summary table of the peak areas of the pyrolysis gas chromatography components of the well to be evaluated, and calculate the component distortion coefficient Kz value of the sample of the well to be evaluated.

[0052] S6. Plot the component distortion coefficient Kz value of the sample from the well to be evaluated onto the reservoir water-cut indicator chart to determine the water-cut of the well to be evaluated.

[0053] Preferably, the method for evaluating formation fluid properties according to the present invention may further include, for example: Figure 2 The following steps are shown:

[0054] S7. Calculate the dominant peak area of ​​each heavy component in multiple samples according to the following formula:

[0055]

[0056] Among them, C hThe area of ​​the dominant peak of the heavy component is expressed in μV·s; nC26…nC33 is the area of ​​the corresponding carbon group component peaks, expressed in μV·s; G: sample weight, expressed in mg; 100: standard substance sample weight, expressed in mg.

[0057] S8, the component distortion coefficient Kz value of each of the multiple samples is the abscissa, and the dominant peak area C of the heavy component is the scalar. h The values ​​are used as the ordinate to create a component distortion coefficient evaluation chart;

[0058] S9, Calculate the dominant peak area C of the heavy components in the sample from the well to be evaluated. h Value; and

[0059] S10, the component distortion coefficient Kz value and the dominant peak area C of the heavy component in the well to be evaluated. h The values ​​are plotted on the component distortion coefficient evaluation chart to determine the formation fluid properties of the well to be evaluated.

[0060] In the examples of this invention, formation fluid properties can be classified according to reservoir water content into water-free oil layers, weakly water-bearing oil-water co-layers, strongly water-bearing and fully water-bearing oil-water layers, and water-free water layers. Correspondingly, samples are numbered sequentially based on their fluid properties determined by oil testing data, and corresponding pyrolysis gas chromatography component peak area summary tables are established for different fluid properties: Samples 1-16 belong to oil layers, and the pyrolysis gas chromatography component peak area summary table can include Oil Layer Pyrolysis Gas Chromatography Component Peak Area Summary Table 1 (see...). Figure 3 Samples 17-32 were classified as oil-water homolayers. A summary table of peak areas of the components from the oil-water homolayer pyrolysis gas chromatography was established (see Table 2). Figure 4 Samples 34-46 belong to the oil-water layer. A summary table of peak areas for the pyrolysis gas chromatographic components of the oil-water layer is established (see Table 3). Figure 5 Samples 47-54 belong to the oil-bearing aqueous layer. A summary table of peak areas of aqueous layer pyrolysis gas chromatography components is established (see Table 4). Figure 6 The summary tables 1-4 above mainly include the peak areas of the components that can be identified in the pyrolysis gas chromatography of the samples. They may also include other parameters related to the samples, such as, but not limited to: well depth, sample weight, daily oil production, daily water production, oil test results, lithology, etc.

[0061] Figure 7 A reservoir water-bearing indicator chart based on summary tables 1-4 is shown. The horizontal axis represents the component distortion coefficient Kz values ​​of multiple samples, and the vertical axis represents the sample number related to fluid properties, dividing the vertical axis from top to bottom into oil-bearing, weakly aquifer, strongly aquifer, and water-bearing zones. The approximate range along the horizontal axis can be defined based on the degree of sample aggregation. Figure 8A panel for evaluating component distortion coefficients based on summary tables 1-4 is shown. The horizontal axis represents the area C of the dominant peak of each heavy component in multiple samples. h The vertical axis represents the component distortion coefficient Kz value for each of the multiple samples. In this component distortion coefficient evaluation chart, samples with different fluid properties cluster in different regions.

[0062] In an embodiment of the present invention, five samples were obtained from layer 2 of well X1 and six samples were obtained from layer 5 of well X2. A summary table of the peak areas of the pyrolysis gas chromatographic components of wells X1 and X2 is shown below. Figure 9 and Figure 10 As shown. Based on the summary tables of peak areas of pyrolysis gas chromatography components from well X1 and well X2, the component distortion coefficient Kz value and the dominant peak area C of heavy components from well X1 and well X2 were calculated respectively. h The values ​​were then used to compare the component distortion coefficient Kz and the dominant peak area C of the heavy components in wells X1 and X2. h The values ​​are respectively plotted onto the already obtained reservoir water content indicator chart and component distortion coefficient evaluation chart. For example... Figure 11 As shown, the X1 well samples all fall within the oil-bearing zone on the reservoir water-bearing indicator chart, while the X2 well samples all fall within the strong water-bearing zone. Figure 12 As shown, the sample from well X1 coincides with the accumulation area of ​​the oil-bearing reservoir sample in the component distortion coefficient evaluation chart, and the sample from well X2 coincides with the accumulation area of ​​the oil-bearing water-bearing reservoir sample in the same chart. Verification showed that the daily oil production from the No. 2 layer of well X1 was 6.27 t, indicating it is an oil-bearing reservoir. The daily oil production from the No. 5 layer of well X2 was 0.03 t, with 3.12 m³ of water. 3 The conclusion is that it is an oil-water-bearing layer, which is consistent with the conclusions of the reservoir water content indicator chart and the component distortion coefficient evaluation chart.

[0063] In summary, based on the analysis of component peak parameters, new component distortion coefficients Kz and dominant peak areas C of heavy components were established according to the peak areas of pyrolysis gas chromatography. h The value reflects the degree of secondary alteration of crude oil, the changes in peak shape after alteration, and the changes in the abundance of heavy hydrocarbon components. It reduces the subjective differences in human judgment, provides a new approach for evaluating formation fluid properties using pyrolysis gas chromatography, improves the interpretation accuracy, and enhances the application level of evaluation logging technology.

[0064] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0065] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately. Furthermore, various different embodiments of this disclosure can also be combined arbitrarily, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for evaluating formation fluid properties, characterized in that, Includes the following steps: S1, obtain multiple samples from different layers within the predetermined area, and extract the peak area of ​​each component peak in the pyrolysis gas chromatography parameters of the multiple samples; S2, collect oil test data of each layer in the predetermined area, determine the fluid properties of the multiple samples based on the oil test data, and use the peak area obtained in step S1 to establish a corresponding summary table of pyrolysis gas chromatography component peak areas for different fluid properties. S3. Calculate the component distortion coefficients of each of the multiple samples based on the summary table of peak areas of the pyrolysis gas chromatography components. The formula for calculating the component distortion coefficients is as follows: Where Kz is the component distortion coefficient, in dimensionless form; C max Carbon area of ​​the main peak, unit: uV.s; ∑C18 - The sum of the peak areas before C18, in µV·s; S4, a reservoir water content indicator chart is established with the component distortion coefficient Kz value of each of the multiple samples as the abscissa and the sample number of the multiple samples as the ordinate. The reservoir water content indicator chart is divided into different regions along the ordinate based on the water content of the fluid properties to which the multiple samples belong. S5, obtain the peak area of ​​each component peak in the pyrolysis gas chromatography parameters of the sample from the well to be evaluated, establish a summary table of the peak areas of the pyrolysis gas chromatography components of the well to be evaluated, and calculate the distortion coefficient Kz value of the components of the sample from the well to be evaluated; and S6, Plot the component distortion coefficient Kz value of the sample from the well to be evaluated onto the reservoir water-cut indicator chart to determine the water-cut of the well to be evaluated.

2. The method according to claim 1, characterized in that, The summary table of peak areas of pyrolysis gas chromatographic components in step S2 includes: Table 1 summarizes the peak areas of components from the gas chromatography of oil layer pyrolysis. Table 2. Summary of peak areas of components in gas chromatography of oil-water co-layer pyrolysis; Table 3 summarizes the peak areas of components in the gas chromatography of oil-containing aqueous pyrolysis. as well as Table 4 summarizes the peak areas of components from aqueous pyrolysis gas chromatography.

3. The method according to claim 2, characterized in that, The reservoir water content indicator chart is divided into oil zone, weak water content zone, strong water content zone, and water zone from top to bottom along the vertical axis based on the water content of the fluid properties of the multiple samples.

4. The method according to claim 3, characterized in that, The method further includes: S7, calculate the dominant peak area of ​​each of the multiple samples according to the following formula: Among them, C h The area of ​​the dominant peak of the heavy component is expressed in μV·s; nC26…nC33 represents the peak area of ​​the corresponding carbon group component, expressed in μV·s; G: sample weight, expressed in mg; 100: standard substance sample weight, expressed in mg. S8, using the component distortion coefficient Kz value of each of the multiple samples as the abscissa and the dominant peak area C of the heavy component as the ordinate. h The values ​​are used as the ordinate to create a component distortion coefficient evaluation chart; S9, Calculate the dominant peak area C of the heavy component in the sample of the well to be evaluated. h Value; and S10, the component distortion coefficient Kz value and the dominant peak area C of the heavy component in the well to be evaluated are... h The values ​​are plotted on the component distortion coefficient evaluation chart to determine the formation fluid properties of the well to be evaluated.

5. The method according to claim 1, characterized in that, Step S1 includes: calculating and processing the component peaks of the pyrolysis gas chromatography of the plurality of samples using a normalization method.

6. The method according to claim 1, characterized in that, In step S3, components that cannot be identified in the pyrolysis gas chromatography of the multiple samples do not participate in ∑C18. - The calculation.

7. The method according to claim 4, characterized in that, The reservoir water content indicator chart and the component distortion coefficient evaluation chart can be continuously updated by introducing new samples and new oil test data.

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