Oil-water layer evaluation method based on standard deviation of homologous coefficient

Abstract

The present application relates to oil and gas logging technical field, especially to a kind of oil-water layer evaluation method based on homologous coefficient standard deviation, to solve the problem that reservoir evaluation cannot objectively reflect reservoir fluid properties when relying on single-point analysis component data.The present application includes the following steps: collecting gas logging data and porosity data of tested oil layer and layer to be interpreted;Calculating effective total hydrocarbon fraction and homologous coefficient standard deviation of tested oil layer and layer to be interpreted;Establishing coordinate system with effective total hydrocarbon fraction of tested oil layer as abscissa and porosity of tested oil layer as ordinate, projecting sample points of tested oil layer into coordinate system, and establishing interpretation chart;Projecting effective total hydrocarbon fraction and porosity of layer to be interpreted into interpretation chart for interpretation.The present application establishes interpretation chart by processing in-layer data to comprehensively reflect the characteristics of in-layer multi-point data, effectively solves the shortcomings of traditional single-point interpretation method, and more accurately reflects reservoir fluid properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas logging, and particularly relates to an oil and water layer evaluation method based on homologous coefficient standard deviation. BACKGROUND

[0002] At present, the logging oil and water layer interpretation and evaluation is mainly based on two aspects of reservoir physical property and oiliness for evaluation, wherein the physical property is generally based on porosity and permeability, and the oiliness is mainly based on gas logging data, the reservoir fluid property is evaluated according to the high and low of total hydrocarbon value, the fullness degree of peak type and component characteristics, and the best point data in the interpretation layer is usually used for evaluation, which can make reasonable interpretation for part of the reservoir, but the low-saturation oil layer has the same oil and water output during oil testing, the total hydrocarbon curve shape is full type, the display values are also higher, the logging data response characteristics are similar to the oil layer, and the reservoir evaluation by relying on single-point analysis of component data cannot objectively reflect the reservoir fluid property, which brings difficulties to the logging interpretation, and the evaluation needs to be combined with the change of layer fluid property. That is, the reservoir evaluation by relying on single-point analysis of component data cannot objectively reflect the reservoir fluid property. SUMMARY

[0003] The present application aims to provide an oil and water layer evaluation method based on homologous coefficient standard deviation, so as to solve the problem that the reservoir evaluation by relying on single-point analysis of component data cannot objectively reflect the reservoir fluid property.

[0004] In order to solve the above technical problem, the technical scheme provided by the present application is as follows:

[0005] An oil and water layer evaluation method based on homologous coefficient standard deviation, comprising the following steps:

[0006] Collecting the gas logging data and porosity data of the tested oil layer and the layer to be interpreted; calculating the effective total hydrocarbon fraction and homologous coefficient standard deviation of the tested oil layer and the layer to be interpreted; establishing a coordinate system with the effective total hydrocarbon fraction of the tested oil layer as the horizontal coordinate and the porosity of the tested oil layer as the vertical coordinate, projecting the sample points of the tested oil layer into the coordinate system, and establishing an interpretation graph plate; projecting the effective total hydrocarbon fraction and porosity of the layer to be interpreted into the interpretation graph plate, and interpreting according to the interpretation area where the falling point is located and the size of the homologous coefficient standard deviation.

[0007] Further, the interpretation graph plate comprises the interpretation areas of oil layer, oil and water layer, oil-bearing water layer, poor oil layer and dry layer.

[0008] Further, different symbols are used to mark the sample points with different fluid properties.

[0009] Further, the shape of the symbol is a square, and the side length of the square of the symbol of the layer with the homologous coefficient standard deviation greater than or equal to 1 is twice the homologous coefficient standard deviation less than 1.

[0010] Further, the oil layer data sample point is represented by ; the oil-water layer data sample point is represented by ; the oil-bearing water layer data sample point is represented by ; the difference oil layer data sample point is represented by ; the dry layer data sample point is represented by ; and the layer data point to be interpreted is represented by .

[0011] Further, the method for calculating the effective total hydrocarbon of each point in the tested oil layer and the layer to be interpreted is as follows:

[0012] TG Y = TG - T j .

[0013] TG Y — effective total hydrocarbon, %;

[0014] TG — total hydrocarbon detection value, %;

[0015] T j — total hydrocarbon base value, %.

[0016] Further, the method for calculating the effective total hydrocarbon fraction of each tested oil layer and the layer to be interpreted is as follows:

[0017] TG Z = TG Y1 + TG Y2 + … + TG Yd .

[0018] TG Z — effective total hydrocarbon fraction of the tested oil layer and the layer to be interpreted;

[0019] TG Y1、 TG Y2 , …, TG Yd is the effective total hydrocarbon of the first meter, the second meter, …, the dth meter in the layer.

[0020] Further, the method for calculating the homologous coefficient of each measurement point is as follows:

[0021] TF = (nC4 + nC5) / (iC4 + iC5);

[0022] TF — homologous coefficient, dimensionless;

[0023] nC4 — normal butane content, %;

[0024] nC5 — normal pentane content, %;

[0025] iC4 — isobutane content, %;

[0026] iC5 - isopentane content, %.

[0027] Further, the method for calculating the standard deviation of the isogeny coefficient of each tested oil layer and the layer to be interpreted is as follows:

[0028]

[0029] S TF the standard deviation of the isogeny coefficient in the layer;

[0030] TF i the isogeny coefficient of the i-th meter in the layer, i = 1, 2, 3…, d;

[0031] the average value of the isogeny coefficient in the layer.

[0032] Further, when the drop point of the layer to be interpreted is in the oil layer or the oil-water layer area, if the standard deviation of the isogeny coefficient is greater than or equal to 1, the layer to be interpreted is an oil-water layer; if the standard deviation of the isogeny coefficient is less than 1, the layer to be interpreted is an oil layer.

[0033] The technical effects that can be achieved by the present application based on the above technical solutions are:

[0034] The oil-water layer evaluation method based on the standard deviation of the isogeny coefficient provided by the present application comprises the following steps: collecting the gas logging data and porosity data of the tested oil layer and the layer to be interpreted; calculating the effective total hydrocarbon fraction and the standard deviation of the isogeny coefficient of the tested oil layer and the layer to be interpreted; establishing a coordinate system with the effective total hydrocarbon fraction of the tested oil layer as the horizontal coordinate and the porosity of the tested oil layer as the vertical coordinate, projecting the sample points of the tested oil layer into the coordinate system, and establishing an interpretation plate; projecting the effective total hydrocarbon fraction and the porosity of the layer to be interpreted into the interpretation plate, and interpreting according to the interpretation area where the drop point is located and the size of the standard deviation of the isogeny coefficient.

[0035] Since the present application processes the data in the layer to establish an interpretation plate by comprehensively considering the characteristics of the multiple points in the layer, and interprets according to the interpretation area where the drop point of the layer to be interpreted is located and the size of the standard deviation of the isogeny coefficient, the shortcomings of the traditional single-point interpretation method are effectively solved, and the reservoir fluid properties are more accurately reflected. In addition, the size of the projection point mark is used to represent the size of the standard deviation of the isogeny coefficient, the three-dimensional data is displayed in a plane, which is more intuitive than the traditional three-dimensional plate, improves the interpretation accuracy of the low-saturation oil layer, reduces the difficulty of oil testing layer selection, is conducive to better playing the role of gas logging technology, and is also conducive to improving the success rate of oil testing and the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0037] Figure 1 The effective total hydrocarbon fraction, porosity, and homologous coefficient standard deviation interpretation chart provided for the embodiments of the present application;

[0038] Figure 2 The N521X well logging comprehensive chart provided for the embodiments of the present application;

[0039] Figure 3 The N521X well interpretation chart provided for the embodiments of the present application;

[0040] Figure 4 The N69X well logging comprehensive chart provided for the embodiments of the present application;

[0041] Figure 5 The N69X well interpretation chart provided for the embodiments of the present application. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art on the basis of the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0044] The following will make a detailed description of some embodiments of the present application in combination with the drawings. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

[0045] There is a problem in the prior art that the reservoir evaluation by relying on single-point analysis of component data cannot objectively reflect the reservoir fluid properties, which brings difficulties to well logging interpretation.

[0046] Therefore, the application provides an oil-water layer evaluation method based on homologous coefficient standard deviation, which comprises the following steps: collecting gas logging data and porosity data of tested oil layers and layers to be interpreted; calculating effective total hydrocarbon fractions and homologous coefficient standard deviations of the tested oil layers and the layers to be interpreted; establishing a coordinate system with the effective total hydrocarbon fractions of the tested oil layers as the horizontal coordinates and the porosities of the tested oil layers as the vertical coordinates, projecting sample points of the tested oil layers into the coordinate system, and establishing an interpretation plate; projecting the effective total hydrocarbon fractions and the porosities of the layers to be interpreted into the interpretation plate, and interpreting according to the interpretation areas where the points fall and the sizes of the homologous coefficient standard deviations.

[0047] The application establishes an interpretation plate by processing in-layer data and comprehensively using in-layer multi-point data, interprets according to the interpretation areas where the points of the layers to be interpreted fall and the sizes of the homologous coefficient standard deviations, effectively solves the shortcomings of the traditional single-point interpretation method, more accurately reflects the reservoir fluid properties, and realizes the plane display of three-dimensional data by using the sizes of the projection point marks to represent the sizes of the homologous coefficient standard deviations, which is more intuitive than the traditional three-dimensional plate, improves the interpretation accuracy of low-saturation oil layers, reduces the difficulty of oil testing and layer selection, is beneficial to better play the role of gas logging technology, and is also beneficial to improve the success rate of oil testing and the production efficiency.

[0048] The following Figures 1-5 The oil-water layer evaluation method based on homologous coefficient standard deviation provided in the embodiment is described in detail as follows:

[0049] The oil-water layer evaluation method based on homologous coefficient standard deviation provided in the embodiment is described in detail as follows:

[0050] S100—collecting gas logging data and porosity data of tested oil layers and layers to be interpreted.

[0051] S200—calculating effective total hydrocarbon fractions and homologous coefficient standard deviations:

[0052] a) the method for calculating the effective total hydrocarbon of each point in the tested oil layers and the layers to be interpreted is as follows:

[0053] TG Y = TG - T j ;

[0054] TG Y — effective total hydrocarbon, %;

[0055] TG— total hydrocarbon detection value, %;

[0056] T j — total hydrocarbon base value, %.

[0057] b) the method for calculating the effective total hydrocarbon fractions of the tested oil layers and the layers to be interpreted is as follows:

[0058] TGZ = TG Y1 + TG Y2 +... + TG Yd ;

[0059] TG Z Effective total hydrocarbon fraction of the tested oil layer and the layer to be interpreted;

[0060] TG Y1、 TG Y2 ,..., TG Yd Effective total hydrocarbon of the 1st meter, the 2nd meter,..., the dth meter in the layer.

[0061] c) The method for calculating the homologous coefficient of each tested oil layer and the layer to be interpreted is as follows:

[0062] TF = (nC4 + nC5) / (iC4 + iC5);

[0063] TF - Homologous coefficient, dimensionless;

[0064] nC4 - Normal butane content, %;

[0065] nC5 - Normal pentane content, %;

[0066] iC4 - Isobutane content, %;

[0067] iC5 - Isopentane content, %.

[0068] d) The method for calculating the standard deviation of the homologous coefficient of each tested oil layer and the layer to be interpreted is as follows:

[0069]

[0070] S TF - Standard deviation of the homologous coefficient in the layer;

[0071] TF i - Homologous coefficient of the ith meter in the layer, i = 1, 2, 3,..., d;

[0072] - Average value of the homologous coefficient in the layer.

[0073] It should be noted that the sampling interval can be determined according to the situation. For example, gas logging data and porosity are collected at intervals of 0.1 meters, 0.2 meters, etc. At this time, i is only used for counting, indicating the sampling point number. Usually, it is collected at intervals of 1 meter, and the maximum value of the collected data within 1 meter is selected.

[0074] In addition, it is necessary to ensure that the sampling interval of the tested oil layer and the layer to be interpreted is consistent.

[0075] S300—Establishing a coordinate system with the effective full hydrocarbon fraction of the tested oil layer as the abscissa and the porosity of the tested oil layer as the ordinate, projecting the sample points of the tested oil layer into the coordinate system, and establishing an interpretation plate.

[0076] As shown in Figure 1 , the interpretation regions of oil layer, oil-water layer, oil-bearing water layer, poor oil layer and dry layer are determined according to the landing points of each sample point. Different symbols are used to mark different fluid properties on the interpretation plate. Specifically, square symbols filled with different lines are used for marking, and oil layer data sample points are represented by ; oil-water layer data sample points are represented by ; oil-bearing water layer data sample points are represented by ; poor oil layer data sample points are represented by ; dry layer data sample points are represented by ; and to-be-interpreted layer data points are represented by . At the same time, the length of the square of the layer with a homologous coefficient standard deviation greater than or equal to 1 on the interpretation plate is twice that of the layer with a homologous coefficient standard deviation less than 1.

[0077] S400—Projecting the effective full hydrocarbon fraction and porosity of the to-be-interpreted layer into the interpretation plate, and interpreting according to the interpretation region where the landing point is located and the size of the homologous coefficient standard deviation:

[0078] It should be noted that when multiple hydrocarbons are dissolved in water, the solubility of isoparaffin and n-paraffin in water is different, so the ratio of the two, i.e. the homologous coefficient, can be used to determine whether the formation contains water. The standard deviation reflects the dispersion degree of a group of data, so when the formation contains two or more fluids, the homologous coefficients of different points in the layer will have a large difference, and the value of the standard deviation will also be relatively high. When the formation is a single fluid, the data is more concentrated, and the standard deviation is also smaller. Therefore, the homologous coefficient standard deviation can be used to finely divide oil layers and oil-water layers.

[0079] That is, when the landing point of the to-be-interpreted layer is in the oil layer or oil-water layer region, if the homologous coefficient standard deviation is greater than or equal to 1, the to-be-interpreted layer is an oil-water layer; if the homologous coefficient standard deviation is less than 1, the to-be-interpreted layer is an oil layer.

[0080] The oil-water layer evaluation method based on the homologous coefficient standard deviation provided in this embodiment is applied as follows:

[0081] An interpretation plate is established according to the data of the tested oil layer, and an interpretation plate as shown in Figure 1 is obtained. For the to-be-interpreted layer, gas logging data and porosity are collected at intervals of 1 meter, and the effective full hydrocarbon fraction and the homologous coefficient standard deviation are calculated, and the effective full hydrocarbon fraction and the porosity of the to-be-interpreted layer are projected into the interpretation plate, and an interpretation plate as shown in Figure 3 , Figure 5 is obtained.

[0082] Layer 1 to be interpreted: Layer 4 of well N521X, well depth 2718-2729m, layer thickness 11m, logging data shown in Table 1, baseline value 0.68%, if... Figure 2 The middle lead 1 points to; calculate the effective total hydrocarbons, such as Figure 2 The middle lead 2 indicates that the porosity, as obtained from collected data, is 18.3%, and the calculated effective total hydrocarbon fraction is 24.429%. Figure 3 The explanatory chart shown depicts the oil layer and the oil-water co-layer area, as... Figure 3 superior The marked location. The calculated standard deviation of the homology coefficient is 1.07, therefore it is interpreted as an oil-water co-layer. Oil testing of this layer yielded 8.5 m³ of oil per day. 3 Daily water production 4.7m 3 The explanation and conclusion are consistent with the oil test results.

[0083] Table 1: Logging data of well N521X, layer 4

[0084]

[0085]

[0086] Layer 2 to be interpreted: Layer 2 of well G69X, depth 2640-2648m, thickness 8m, logging data shown in Table 2, baseline value 0.593%, if... Figure 4 The middle lead 3 points to; calculate the effective total hydrocarbons. Figure 4 The middle lead 4 points to the data. The collected data shows a porosity of 19.5%, and the calculated effective total hydrocarbon fraction is 26.449%. Figure 5 The explanatory chart shown depicts the oil layer and the oil-water co-layer area, as... Figure 5 superior The marked location, with a calculated homology coefficient standard deviation of 0.44, is therefore interpreted as an oil layer. Oil testing of this layer yielded a daily oil production of 10.27 m³. 3 It is a pure oil layer, and the interpretation conclusion is consistent with the oil test conclusion.

[0087] Table 2: Logging data of layer 4 in well G69X

[0088]

[0089] By processing the data within the layer and integrating the characteristics of multi-point data within the layer, the shortcomings of traditional single-point interpretation methods are effectively solved. The size of the projection point marker is used to represent the standard deviation of the homogeneous coefficient, realizing a planar display of three-dimensional data, which is more intuitive than traditional three-dimensional charts. This improves the interpretation accuracy of low-saturation oil layers, reduces the difficulty of oil testing and layer selection, and is conducive to better leveraging the role of gas testing technology. It is also conducive to improving the success rate of oil testing and production efficiency.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating oil-water reservoirs based on the standard deviation of the homogeneity coefficient, characterized in that, Includes the following steps: Collect gas logging data and porosity data of tested oil layers and layers to be interpreted; Calculate the effective total hydrocarbon fraction and the standard deviation of the homology coefficient for the tested and uninterpreted oil layers; A coordinate system is established with the effective total hydrocarbon fraction of the tested oil layer as the abscissa and the porosity of the tested oil layer as the ordinate. The sample points of the tested oil layer are projected onto the coordinate system to create an interpretation chart. The effective total hydrocarbon fraction and porosity of the layer to be interpreted are projected onto the interpretation chart, and the interpretation is performed based on the interpretation region where the landing point is located and the magnitude of the standard deviation of the homology coefficient. The interpretation panel includes interpretation areas for oil layers, oil-water co-layers, oil-water-containing layers, poor oil layers, and dry layers; The method for calculating the homology coefficient of each measurement point is as follows: TF = (nC4 + nC5) / (iC4 + iC5); TF—homology coefficient, dimensionless; nC4—n-Butane content, % nC5—n-pentane content, % iC4—isobutane content, % iC5—isopentane content, % The method for calculating the standard deviation of the homology coefficients of each tested oil layer and the layer to be interpreted is as follows: ； S TF —Standard deviation of the homology coefficient within the layer; TF i — Homology coefficients at the i-th meter within the layer, i=1,2,3¼,d; —The average value of the homology coefficients within the layer; When the layer to be interpreted falls in the oil layer or the oil-water co-layer region, if the standard deviation of the homogeneity coefficient is greater than or equal to 1, then the layer to be interpreted is an oil-water co-layer. If the standard deviation of the homology coefficient is less than 1, then the layer to be interpreted is an oil layer.

2. The method for evaluating oil-water reservoirs based on the standard deviation of the homogeneity coefficient according to claim 1, characterized in that... Different symbols are used to label sample points with different fluid properties.

3. The oil-water layer evaluation method based on the standard deviation of the homogeneity coefficient according to claim 2, characterized in that, The symbol is square in shape, and for layers with a standard deviation of homology coefficient greater than or equal to 1, the side length of the square of the symbol is twice that of layers with a standard deviation of homology coefficient less than 1.

4. The oil-water layer evaluation method based on the standard deviation of the homogeneity coefficient according to claim 1, characterized in that, The method for calculating the effective total hydrocarbons at each point within the tested and uninterpreted reservoirs is as follows: TG Y =TG-T j ; TG Y —Effective total hydrocarbons, % TG—Total hydrocarbons, % T j —Total hydrocarbon value, %.

5. The oil-water layer evaluation method based on the standard deviation of the homogeneity coefficient according to claim 4, characterized in that, The method for calculating the effective total hydrocarbon fraction of each tested and uninterpreted oil layer is as follows: TG Z =TG Y1 +TG Y2 +…+TG Yd ; TG Ｚ —Effective total hydrocarbon fraction of tested and uninterpreted reservoirs; TG Y1、 TG Y2 , ..., TG Yd The effective total hydrocarbons in the 1st meter, 2nd meter, ..., dth meter of the layer.

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