Fluid property evaluation method based on characterization gas logging total hydrocarbon form quality factor

Abstract

The invention relates to the technical field of oil field gas logging, in particular to a fluid property evaluation method based on factors representing gas logging total hydrocarbon form quality, which comprises the following steps of: 1, performing well depth homing on gas logging data in a research area according to lithology, drilling time and logging information, and dividing gas logging abnormal sections; 2, constructing a QTG representing gas logging total hydrocarbon form quality factor, and calculating a QTG value of a gas logging abnormal section; and step 3, analyzing data of a tested oil and gas well in the research area, and establishing a QTG discrimination standard for fluid property evaluation according to a characterization relationship between the characterization gas logging total hydrocarbon form quality factor QTG and an oil-gas-water layer. According to the method, the information contained in the gas logging total hydrocarbon form is fully excavated, the fluid property of the oil and gas well is rapidly, visually and efficiently judged on site, and effective technical support is provided for oil testing layer position optimization and regional exploration and development.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield gas logging and well logging, and is a fluid property evaluation method based on a quality factor characterizing the gas logging total hydrocarbon form. Background Art

[0002] Gas logging is an important geological exploration technology, mainly used to detect the distribution and content of underground gas. With the continuous deepening of oil and gas exploration, gas logging technology has also been continuously developed and improved.

[0003] Traditional gas logging methods mainly include gas tracer method, gas chromatography, etc. Gas logging detection parameters include total hydrocarbons, hydrocarbon components (7 items including methane, ethane, propane, isobutane, n-butane, isopentane, and n-pentane), and non-hydrocarbon components (3 items including carbon dioxide, hydrogen sulfide, and hydrogen), totaling 11 items.

[0004] With the rapid development of computer technology and information technology, many new gas logging technologies have emerged, such as digital logging, high-resolution transmission system, laser detection, etc. These technologies have the advantages of high accuracy, high speed, and easy operation, and have been widely used in oil and gas exploration.

[0005] The key technologies in gas logging include data processing and data interpretation. Among them, data processing technologies include data cleaning, feature extraction, pattern recognition, etc.; data interpretation technology needs to combine geological knowledge and experience to analyze and interpret gas logging data. At present, gas logging technology has been continuously developed and improved, such as digital technology, artificial intelligence technology, etc. At the same time, gas logging also pays more attention to the combination with other exploration technologies, such as seismic exploration, drilling fluid, logging, etc., to form a complete geological exploration system. In summary, gas logging is an important geological exploration technology, and its background technology includes traditional methods and new technologies. At the same time, it is also necessary to pay attention to key technologies such as data processing and data interpretation. With the continuous advancement of science and technology, gas logging technology will continue to be improved and developed to provide more accurate data support for oil and gas exploration.

[0006] The existing oil and gas interpretation of gas logging includes Pixler chart, double logarithmic chart, triangle chart, 3H method chart and the multi-parameter interpretation chart of logging that has emerged in recent years. The existing technology has the following shortcomings: ① The traditional Pixler chart, double logarithmic chart, triangle chart and 3H method chart are mainly established based on the ratio between gas logging components, without considering the formation fluid information contained in the total hydrocarbon data. ② Although the multi-parameter interpretation chart of logging takes all hydrocarbons into consideration, there are still some problems with the morphological characterization that is not rigorous enough. For example, for the same box shape, there are factors with different gas logging anomaly amplitudes. ③ The equilateral triangle and inverted triangle shapes of the total hydrocarbon curve cannot be distinguished. Due to the vertical heterogeneity of the reservoir, the positive rhythm of the lithology grain size leads to poor physical properties at the top and good at the bottom, resulting in a positive triangle shape of the total hydrocarbon curve. The total hydrocarbon value of the gas test in the display section increases with the increase of well depth, and the maximum value is at the bottom (or lower part) of the abnormal display section; on the contrary, the negative rhythm of the lithology grain size leads to good physical properties at the top and poor physical properties at the bottom, resulting in an inverted triangle shape of the total hydrocarbon curve. The total hydrocarbon value of the gas test in the display section decreases with the increase of well depth, and the maximum value is at the top (or upper part) of the abnormal display section. These two situations often reflect different fluid characteristics (see Figure 1 Schematic diagram of the quality of gas logging total hydrocarbon morphology). The information resources contained in the gas logging total hydrocarbon morphology have not been fully explored, and the quality of the gas logging total hydrocarbon morphology cannot be accurately reflected by relying solely on the hydrocarbon filling coefficient. The above-mentioned shortcomings lead to a large deviation between the gas logging interpretation results of complex reservoirs and the actual situation, and the interpretation conformity rate is low, which cannot meet the existing oil and gas layer exploration needs.

[0007] Therefore, how to propose a new calculation method to accurately characterize the quality of the total hydrocarbon form of gas measurement, so that it can reasonably reflect the oil, gas and water characteristics under different forms, and make the accuracy of oil and gas layer identification meet the needs of existing oil and gas layer exploration, is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0008] The present invention provides a fluid property evaluation method based on characterizing the quality factor of the total hydrocarbon morphology of gas logging, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem of low gas logging interpretation compliance rate caused by the prior art's inaccurate characterization of gas logging morphology.

[0009] The technical solution of the present invention is achieved by the following measures: A fluid property evaluation method based on characterizing the quality factor of the total hydrocarbon form of gas measurement is carried out according to the following steps:

[0010] The first step is to perform well depth relocation of gas logging data in the study area according to lithology, drilling time and logging data, and divide the gas logging abnormal section;

[0011] The second step is to construct the quality factor QTG that characterizes the total hydrocarbon morphology of gas logging and calculate the QTG value of the abnormal section of gas logging. The expression of QTG is:

[0012]

[0013] Among them, QTG is the quality factor characterizing the total hydrocarbon morphology of gas logging, which is dimensionless; TGmax is the peak value of the total hydrocarbon curve of gas logging, in %; TGbase is the background value of total hydrocarbon of gas logging in the non-reservoir section before the abnormal section of gas logging, in %; TGave is the arithmetic mean of total hydrocarbon in the abnormal section of gas logging, in %; k is the slope of the linear fitting equation of the total hydrocarbon value of the abnormal section of gas logging and the well depth, which is dimensionless.

[0014] The third step is to analyze the data of the tested oil and gas wells in the study area, and establish the QTG discrimination standard for fluid property evaluation based on the relationship between the quality factor QTG characterizing the total hydrocarbon morphology of gas logging and the characterization of oil, gas and water layers.

[0015] The following are further optimizations and / or improvements to the above technical solutions:

[0016] In the second step, TGbase is the average value of all hydrocarbons in the non-reservoir section of 2 m to 10 m before the abnormal section.

[0017] In the second step above, the slope k of the linear fitting equation of the total hydrocarbon value and well depth in the abnormal gas logging section is obtained by the following steps:

[0018] With well depth as the independent variable and total hydrocarbon value of the abnormal gas logging section as the dependent variable, a scatter plot of well depth and total hydrocarbon of the abnormal gas logging section was drawn and a linear fit was performed. The linear fitting equation is as follows:

[0019] TG = k × depth + b Formula 2

[0020] Among them, TG is the total hydrocarbon value of gas logging, depth is the well depth, k is the slope, and b is the coefficient.

[0021] In the second step above, the gas logging total hydrocarbon curve shape categories are divided according to the slope k of the linear fitting equation between the total hydrocarbon value of the gas logging abnormal section and the well depth. The classification criteria are as follows:

[0022] When k<-0.5, the gas logging total hydrocarbon curve is in the shape of an inverted triangle;

[0023] When -0.5≤k≤0.5, the gas logging total hydrocarbon curve is box-shaped;

[0024] When k>0.5, the gas logging total hydrocarbon curve is in the shape of an equilateral triangle.

[0025] The specific operation of the third step is: draw a data distribution line graph of the gas testing total hydrocarbon morphology quality factor QTG of the tested oil and gas wells in the study area, and according to the location of the valuable layer and the non-valuable layer in the QTG data distribution line graph, count the return judgment compliance rate under different QTG values, and select the QTG value with high overall value layer judgment compliance and the maximum return judgment compliance rate as the QTG discrimination standard for fluid property evaluation.

[0026] The above-mentioned valuable layers are oil layers, gas layers or oil-water layers, and the non-valuable layers are oil-water layers, oil-bearing layers, water layers or dry layers.

[0027] The present invention fully exploits the information contained in the total hydrocarbon morphology of gas logging, effectively solves the problems of weak differentiation and low compliance rate in the prior art, and realizes on-site rapid, intuitive and efficient judgment of the fluid properties of oil and gas wells, providing effective technical support for the optimization of test oil layers and regional exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Attached Figure 1 It is a schematic diagram of the quality of total hydrocarbons measured by gas in the present invention.

[0029] Attached Figure 2 This is the comprehensive logging diagram of the SX163 well in Example 7 of the present invention.

[0030] Attached Figure 3 This is a scatter plot of total hydrocarbons in the 4766m-4775m section of the SX163 well and the well depth in Example 7 of the present invention.

[0031] Attached Figure 4 This is a line graph of QTG data distribution in Example 7 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0033] The present invention will be further described below in conjunction with embodiments:

[0034] Example 1: The fluid property evaluation method based on characterizing the gas-measured total hydrocarbon morphology quality factor is carried out according to the following steps:

[0035] The first step is to perform well depth relocation of gas logging data in the study area according to lithology, drilling time and logging data, and divide the gas logging abnormal section;

[0036] The second step is to construct the quality factor QTG that characterizes the total hydrocarbon morphology of gas logging and calculate the QTG value of the abnormal section of gas logging. The expression of QTG is:

[0037]

[0038] Among them, QTG is the quality factor characterizing the total hydrocarbon morphology of gas logging, which is dimensionless; TGmax is the peak value (maximum value) of the total hydrocarbon curve of gas logging, in %; TGbase is the background value of total hydrocarbon of gas logging in the non-reservoir section before the abnormal section of gas logging, in %; TGave is the arithmetic mean of total hydrocarbon in the abnormal section of gas logging, in %; k is the slope of the linear fitting equation of the total hydrocarbon value of the abnormal section of gas logging and the well depth, which is dimensionless.

[0039] The third step is to analyze the data of the tested oil and gas wells in the study area, and establish the QTG discrimination standard for fluid property evaluation based on the relationship between the quality factor QTG characterizing the total hydrocarbon morphology of gas logging and the characterization of oil, gas and water layers.

[0040] Example 2: As an optimization of the above example, in the second step, TGbase is the average value of all hydrocarbons in the non-reservoir section of 2 m to 10 m before the abnormal gas logging section.

[0041] Example 3: As an optimization of the above example, in the second step, the slope k of the linear fitting equation of the total hydrocarbon value and well depth in the abnormal gas logging section is obtained by the following steps:

[0042] With well depth as the independent variable and total hydrocarbon value of the abnormal gas logging section as the dependent variable, a scatter plot of well depth and total hydrocarbon of the abnormal gas logging section was drawn and a linear fit was performed. The linear fitting equation is as follows:

[0043] TG = k × depth + b Formula 2

[0044] Among them, TG is the total hydrocarbon value of gas logging, depth is the well depth, k is the slope, and b is the coefficient.

[0045] Example 4: As an optimization of the above example, the gas logging total hydrocarbon curve shape categories are divided according to the slope k of the linear fitting equation of the total hydrocarbon value of the abnormal gas logging section and the well depth. The classification criteria are as follows:

[0046] When k<-0.5, the gas logging total hydrocarbon curve is in the shape of an inverted triangle;

[0047] When -0.5≤k≤0.5, the gas logging total hydrocarbon curve is box-shaped;

[0048] When k>0.5, the gas logging total hydrocarbon curve is in the shape of an equilateral triangle.

[0049] The box shape in the present invention includes nearly box shape, finger shape, peak shape, wave shape and the like.

[0050] Example 5: As an optimization of the above example, the specific operation of the third step is: draw a data distribution line graph of the gas quality factor QTG of the tested oil and gas wells in the study area, and according to the location of the valuable layer and the non-valuable layer in the QTG data distribution line graph, count the return judgment compliance rate under different QTG values, and select the QTG value with high overall value layer judgment compliance and the maximum return judgment compliance rate as the QTG discrimination standard for fluid property evaluation.

[0051] Embodiment 6: As an optimization of the above embodiment, the valuable layer is an oil layer, a gas layer or an oil-water layer, and the non-valuable layer is an oil-water layer, an oil-containing layer, a water layer or a dry layer.

[0052] The present invention takes the gas logging abnormal section as the research object, firstly calculates the gas logging total hydrocarbon background value TGbase of the non-reservoir section before the gas logging abnormal section appears, and then calculates the total hydrocarbon peak value (maximum value) TGmax and the total hydrocarbon arithmetic mean value TGave of the gas logging abnormal section. With these three items as basic parameters, two new parameters are derived: one is the ratio of the total hydrocarbon peak value to the background value. The first is the peak-to-base ratio (its value range is > 1), which can reflect the magnitude of gas logging anomalies; the second is the ratio between the arithmetic mean of total hydrocarbons and the total hydrocarbon peak value (maximum value). This ratio can reflect the box-shaped degree of the gas logging total hydrocarbon curve. The closer the ratio is to 1, the higher the box-shaped degree is. It is named the box-shaped index.

[0053] At the same time, in order to distinguish the equilateral triangle and inverted triangle of the total hydrocarbon curve, according to the change trend of total hydrocarbon with the increase of well depth, the slope k of the linear fitting equation of total hydrocarbon value and well depth in the abnormal section of gas logging is used to characterize this characteristic. When k < -0.5, the total hydrocarbon of gas logging decreases with the increase of well depth, the total hydrocarbon curve is in an inverted triangle, and the maximum value of total hydrocarbon is at the top (or upper part); when k > 0.5, the total hydrocarbon of gas logging increases with the increase of well depth, the total hydrocarbon curve is in an equilateral triangle, and the maximum value of total hydrocarbon is at the bottom (or lower part). On this basis, the peak-to-base ratio, box index and slope k are used to construct a quality factor QTG to characterize the shape of gas logging total hydrocarbon. This factor QTG integrates three pieces of information: (1) the magnitude of the abnormal amplitude of gas logging total hydrocarbon, which can reflect the quality of oil and gas display; (2) the box degree of gas logging total hydrocarbon, which can reflect the vertical filling degree of oil and gas and the homogeneity of oil and gas display; (3) the positive and negative values ​​of the slope k are used to distinguish whether the shape of the gas logging total hydrocarbon curve is an equilateral triangle or an inverted triangle. In view of the non-ideal characteristics of the actual total hydrocarbon curve, the slope ranges of different curve characteristics are statistically analyzed, and the slope interval standards of regular triangle, box shape, and inverted triangle are defined. The quality factor QTG for characterizing the total hydrocarbon morphology of gas measurement established by the present invention overcomes the shortcomings of the prior art, fully explores the information contained in the total hydrocarbon morphology of gas measurement, and effectively solves the problems of weak distinction and low compliance rate existing in the prior art.

[0054] Example 7: The present invention is applied to the clastic oil and gas reservoirs in Fudong and Shixi areas of Junggar Basin. The fluid properties are quickly determined on site based on the total hydrocarbon morphology quality factor QTG of the characterization gas test. The specific operation is as follows:

[0055] According to the lithology, drilling time and logging data, the gas logging data is returned to the well depth to improve the consistency between the gas logging data and other data, so that the gas logging data shows a relatively uniform response characteristic under the same geological conditions. Generally, this step is done by the on-site logging geologist after the well logging is completed. The logging data after the return is shown in Figure 2 . The gas logging abnormal section is divided according to the comprehensive logging diagram.

[0056] For the abnormal gas logging section 4769m-4775m of Well SX163, the average value of total hydrocarbons in the non-reservoir section 4735m-4740m was first taken as the total hydrocarbon background value TGbase, and then the total hydrocarbon peak value TGmax and the arithmetic mean value TGave of this abnormal gas logging section were calculated (see Table 1 for specific values).

[0057] With well depth as the independent variable and total hydrocarbon (TG) as the dependent variable, a scatter plot of well depth and total hydrocarbon in the gas logging abnormal section was drawn and a linear fit was performed (see Figure 3 ), the slope k of the linear fitting equation of the total hydrocarbon value and well depth in the abnormal gas logging section is -1.22. k<-0.5, the gas logging total hydrocarbon curve shows an inverted triangle feature.

[0058] According to formula 1, the QTG of the abnormal gas logging section 4769m-4775m is calculated to be 31.14.

[0059] Draw a line graph of the QTG data distribution of the wells that have been tested for oil and gas in the well area (see Figure 4 ), according to the location of the value layer and the non-value layer in the QTG data distribution line chart, the return judgment compliance rate when QTG is 20, 30 and 40 is counted respectively. In order to avoid misjudgment of the value layer, the value layer judgment compliance is the best as the first principle, and then the QTG value with the maximum overall compliance rate is selected as the judgment standard for fluid property evaluation. Finally, the QTG judgment standard for fluid property evaluation in this area is determined as follows: QTG ≥ 30 is a value layer, and QTG < 30 is a non-value layer. According to this standard, the return judgment compliance rate of the value layer is 72.7%, and the overall sample return judgment compliance rate is 74.3%. The QTG of the abnormal section 4769m-4775m of the gas test is 31.14, and the gas test is quickly interpreted as a value layer. The oil test of SX163 well 4769m-4775m is oil and water in the same layer, and the interpretation result is consistent with the oil test conclusion.

[0060] According to the method of the present invention, the QTG discrimination of fluid property evaluation was performed on the well sections of SX163 well 4741m-4750m, F54 well 5574m-5581m, F54 well 5650m-5676m and F54 well 5913m-5921m in the well area, and the interpretation results are shown in Table 1. The method of the present invention can evaluate the fluid properties of oil and gas wells quickly, intuitively and efficiently, with a gas logging interpretation compliance rate of 80%, providing effective technical support for the optimization of test oil layers and regional exploration and development.

[0061] In summary, the present invention is based on oil test results and gas logging parameters, and finely analyzes the response characteristics of gas logging total hydrocarbon curves in different fluid types. Through mathematical statistics and combination, an intuitive expression form is used to construct a quality factor QTG characterizing the gas logging total hydrocarbon morphology, and a QTG discrimination standard for fluid property evaluation is established, which realizes on-site rapid, intuitive and efficient judgment of the fluid properties of oil and gas wells, and provides effective technical support for oil test layer optimization and regional exploration and development.

[0062] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

[0063] Table 1

[0064]

Claims

1. A fluid property evaluation method based on characterizing the total hydrocarbon morphology quality factor of gas measurement, characterized in that Follow these steps: The first step is to perform well depth relocation of gas logging data in the study area according to lithology, drilling time and logging data, and divide the gas logging abnormal section; The second step is to construct the quality factor QTG that characterizes the total hydrocarbon morphology of gas logging and calculate the QTG value of the abnormal section of gas logging. The expression of QTG is: Among them, QTG is the quality factor characterizing the total hydrocarbon morphology of gas logging, dimensionless; TGmax is the peak value of the total hydrocarbon curve of gas logging, unit is %; TGbase is the background value of total hydrocarbon of gas logging in the non-reservoir section before the abnormal section of gas logging, unit is %; TGave is the arithmetic mean value of total hydrocarbon in the abnormal section of gas logging, unit is %; k is the slope of the linear fitting equation of total hydrocarbon value and well depth in the abnormal section of gas logging, dimensionless; The third step is to analyze the data of the tested oil and gas wells in the study area, and establish the QTG discrimination standard for fluid property evaluation based on the relationship between the quality factor QTG characterizing the total hydrocarbon morphology of gas logging and the characterization of oil, gas and water layers.

2. The fluid property evaluation method based on characterizing the total hydrocarbon morphology quality factor of gas measurement according to claim 1 is characterized in that In the second step, TGbase is the average value of all hydrocarbons in the non-reservoir section from 2 m to 10 m before the abnormal section in gas logging.

3. The fluid property evaluation method based on characterizing the gas-measured total hydrocarbon morphology quality factor according to claim 1 or 2, characterized in that In the second step, the slope k of the linear fitting equation of total hydrocarbon value and well depth in the abnormal gas logging section is obtained by the following steps: With well depth as the independent variable and total hydrocarbon value of the abnormal gas logging section as the dependent variable, a scatter plot of well depth and total hydrocarbon of the abnormal gas logging section was drawn and a linear fit was performed. The linear fitting equation is as follows: TG = k × depth + b Formula 2 Among them, TG is the total hydrocarbon value of gas logging, depth is the well depth, k is the slope, and b is the coefficient.

4. The method for evaluating fluid properties based on characterizing the total hydrocarbon morphological quality factor of gas measurement according to any one of claims 1 to 3, characterized in that In the second step, the gas logging total hydrocarbon curve shape categories are divided according to the slope k of the linear fitting equation of the total hydrocarbon value and well depth in the gas logging abnormal section. The classification criteria are as follows: When k<-0.5, the gas logging total hydrocarbon curve is in the shape of an inverted triangle; When -0.5≤k≤0.5, the gas logging total hydrocarbon curve is box-shaped; When k>0.5, the gas logging total hydrocarbon curve is in the shape of an equilateral triangle.

5. The fluid property evaluation method based on characterizing the total hydrocarbon morphology quality factor of gas measurement according to any one of claims 1 to 4, characterized in that The specific operation of the third step is: draw a data distribution line graph of the gas testing total hydrocarbon morphology quality factor QTG for the tested oil and gas wells in the study area, and according to the location of the valuable layer and the non-valuable layer in the QTG data distribution line graph, count the return judgment compliance rate under different QTG values, and select the QTG value with high overall value layer judgment compliance and the maximum return judgment compliance rate as the QTG discrimination standard for fluid property evaluation.

6. The method for evaluating fluid properties based on characterizing the total hydrocarbon morphology quality factor of gas measurement according to claim 5, characterized in that The valuable layers are oil layers, gas layers or oil-water layers, and the non-valuable layers are oil-water layers, oil-bearing layers, water layers or dry layers.

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