A method for judging the fluid properties of oil and gas layers based on gas logging

Abstract

The present invention provides a method for judging the fluid properties of oil and gas layers according to gas logging, comprising: step one, downhole fluid sampling; step two, determining the fluid properties of the oil and gas reservoir where the fluid sample is located; step three, performing gas logging method identification parameters on the same fluid sample; step four, constructing a gas logging identification chart: using cp5 as the horizontal coordinate and wh as the vertical coordinate; corresponding the gas logging parameter wh to the fluid properties corresponding to cp5; dividing the gas logging identification chart into the following areas: dry gas and water layer, wet gas and water layer, light oil and water layer, light oil and water layer, residual oil and water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer; step five, obtaining gas logging data of the well to be tested, and judging the fluid type of the oil and gas reservoir of the well to be tested by the area where it is located. Based on the gas logging correction, the present invention uses the combination of cp5 and wh parameters to establish an oil and gas layer identification chart, thereby improving the accuracy of oil and gas layer identification.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to the technical field of a method for judging the type of oil and gas reservoirs by using gas measurement data. Background Art

[0002] The fluid properties of the oil and gas fields in the Xihu Sag of the East China Sea are relatively complex, with condensate gas, volatile oil, light oil and residual oil distributed vertically. Especially when the stratum is buried deep, the temperature and pressure are high (160°C, 40Mpa), the reservoir properties are poor, and the fluid signal in the pores is weak in the logging response, resulting in no obvious difference in the neutron density response of the oil and gas layers. It is difficult to identify the fluid properties of the oil and gas layers based on the logging curve alone.

[0003] At present, the oil and gas layer type is mainly determined by gas logging triangle plates and component distribution curves, but these methods have strong regional characteristics and great limitations, and the identification error is large; in addition, in the existing patent document CN108894778A, the gas logging plate made by Bh*10+sz-wh and C1 / (C2+C3+C4+C5) is not accurate in the classification of oil and gas reservoirs, and requires a lot of data processing. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for determining the fluid properties of oil and gas layers based on gas logging, so as to solve the problem of determining the fluid properties of oil and gas layers through gas logging charts in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a method for determining the properties of oil and gas layer fluids based on gas logging, comprising:

[0006] Step 1: Downhole fluid sampling;

[0007] Step 2: determining the type of the fluid sample and the fluid properties of the oil and gas reservoir where the fluid sample is located;

[0008] Step 3: Perform gas logging method identification parameters on the same fluid sample, and obtain gas logging parameters wh and cp5;

[0009] Step 4, construct a gas measurement identification chart: use wh as the horizontal coordinate and cp5 as the vertical coordinate; correspond the gas measurement parameter wh to the fluid property corresponding to cp5; divide the gas measurement identification chart into the following areas: dry gas and water layer, wet gas and water layer, light oil and water layer, light oil and water layer, residual oil and water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer;

[0010] Step 5: Obtain the gas measurement data of the well to be measured, project the gas measurement data to the gas measurement identification plate, and determine the fluid type of the oil and gas reservoir of the well to be measured based on the area where the data is located.

[0011] Preferably, in step 3, the calculation formulas of wh and cp5 are:

[0012] wh=C2%+C3%+C4%+C5%

[0013]

[0014] In the formula, C1% is the methane content, C2% is the ethane content, C3% is the propane content, C4% is the butane content, and C5% is the pentane content.

[0015] Preferably: the methane content is C1%=C1 / Tg*100; the ethane content C2%=C2 / Tg*100; the propane content C3%=C3 / Tg*100; the butane content C4%=C4 / Tg*100; the pentane content C5%=C5 / Tg*100; Tg=C1%+C2%+C3%+C4%+C5%.

[0016] Preferably: the step 1 obtains fluid sample data through oil and gas layer testing and sampling in exploration wells and production well commissioning.

[0017] Preferably: in the step 2, based on the high-pressure physical property experimental analysis, the fluid properties of the oil and gas reservoir are determined according to the gas-oil ratio, crude oil density, and heavy component content parameters.

[0018] As described above, the method of judging the properties of oil and gas layer fluids based on gas logging of the present invention has the following beneficial effects:

[0019] Based on the gas logging correction, the present invention uses the cp5 and wh parameter combination to establish the oil and gas layer identification chart for the first time. For the first time, the ratio of the alkane component to the total hydrocarbon (TG) is calculated, which plays a role of standardization. According to the application situation, the chart has a good application effect, improves the accuracy of oil and gas layer identification, improves the application scope of gas logging and the accuracy of oil and gas layer identification, and meets the requirements of oil and gas seismic exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a first gas layer identification diagram of a method for judging the fluid properties of oil and gas layers according to gas logging of the present invention;

[0021] Figure 2 It is a schematic diagram of a second gas layer identification diagram of a method for judging the fluid properties of oil and gas layers according to gas logging of the present invention;

[0022] Figure 3 It shows a schematic diagram of the third gas layer identification plate of a method for determining the fluid properties of oil and gas layers based on gas logging according to the present invention. DETAILED DESCRIPTION

[0023] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0024] See also Figures 1 to 3 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0025] like Figure 1 As shown, the present invention provides a method for determining the properties of oil and gas layer fluids based on gas logging, comprising:

[0026] Step 1: Downhole fluid sampling;

[0027] Step 2: determining the type of the fluid sample and the fluid properties of the oil and gas reservoir where the fluid sample is located;

[0028] Step 3: Perform gas logging method identification parameters on the same fluid sample, and obtain gas logging parameters wh and cp5;

[0029] Step 4, construct a gas measurement identification chart: use wh as the horizontal coordinate and cp5 as the vertical coordinate; correspond the gas measurement parameter wh to the fluid property corresponding to cp5; divide the gas measurement identification chart into the following areas: dry gas and water layer, wet gas and water layer, light oil and water layer, oil and water layer, residual oil and water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer;

[0030] Step 5: Obtain the gas measurement data of the well to be measured, project the gas measurement data onto the gas measurement identification plate, and determine the fluid type of the oil and gas reservoir of the well to be measured based on the area where the data is located.

[0031] The present invention accurately determines the fluid properties of the oil and gas reservoir where the fluid is located (i.e., dry gas-water layer, wet gas-water layer, light oil-water layer, oil-water layer, residual oil-water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer) by downhole fluid sampling; then, the gas measurement data of the fluid sample is obtained by gas logging, and the gas measurement data is sorted to obtain wh and cp5 gas measurement maps, and the fluid properties determined by downhole fluid sampling are divided on the gas measurement map. When it is necessary to judge the properties of the fluid to be measured, it is necessary to use gas logging to obtain wh and cp5 to determine its fluid properties. Although the downhole fluid sampling method is accurate, it is very expensive, so directly measuring the fluid properties by gas logging can save considerable exploration costs.

[0032] In addition, in step 1 of the present invention, in a specific embodiment, gas logging data and test data are collected in the current exploration area. Specifically, fluid sample data is obtained through oil and gas layer testing and sampling of exploration wells and production wells.

[0033] In order to determine the liquid properties of the oil and gas reservoir where the fluid sample is located, the fluid properties of the oil and gas reservoir are determined based on the gas-oil ratio, crude oil density, and heavy component content parameters on the basis of high-pressure physical property experimental analysis.

[0034] In order to minimize the influence of residual components in the gas logging method, the effective components are now standardized according to the gas logging component table to analyze the gas logging data and test data. At the same time, based on the standardized gas logging component data, the distinguishing parameters, cp5 heavy hydrocarbon ratio and wh wet gas ratio are calculated:

[0035] wh=C2%+C3%+C4%+C5%

[0036]

[0037] In the formula, C1% is the methane content, C2% is the ethane content, C3% is the propane content, C4% is the butane content, and C5% is the pentane content.

[0038] The methane content is C1%=C1 / Tg*100; the ethane content is C2%=C2 / Tg*100; the propane content is C3%=C3 / Tg*100; the butane content is C4%=C4 / Tg*100; the pentane content is C5%=C5 Tg*100; Tg=C1%+C2%+C3%+C4%+C5%.

[0039] In order to establish a new gas logging identification chart, improve the application scope of gas logging and the accuracy of oil and gas layer identification, and meet the requirements of oil and gas seismic exploration. Now wh is used as the horizontal coordinate and cp5 is used as the vertical coordinate; the gas logging parameters wh and cp5 are graphed; specifically, the gas logging data and test data are analyzed to determine the gas content data; the gas logging data and test data are analyzed to determine the oil content data; the gas logging data and test data are analyzed to determine the water content data.

[0040] Pure gas layer Oil, gas and water layer 0～15％ 15～30％

[0041] Finally, according to Table 1 and the gas-bearing data and oil-bearing data, the first gas layer identification chart is obtained, as shown in Figure 1 As shown;

[0042] Dry gas moisture Light oil General oil layer Residual oil 0～5％ 5～15％ 15～25％ 25～50％ 50～100％

[0043] Table 2

[0044] Based on the oil content data and condensate gas data, Table 2 is summarized and the second gas layer identification chart is obtained, as shown in Figure 2 Finally, the first gas layer identification plate and the second gas layer identification plate are superimposed to form a new oil and gas layer identification plate, as shown in Figure 3 shown.

[0045] In order to confirm that the same corresponding fluid properties correspond to each other; the gas measurement identification plate is divided into the following areas: dry gas and water layer, wet gas and water layer, light oil and water layer, oil and water layer, residual oil and water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer; the first gas layer identification plate and the second gas layer identification plate are overlapped to obtain the oil and gas layer identification plate. In addition, by calculating and fitting a large number of critical data points of the gas-water boundary, it can be obtained Figure 3 Middle curve.

[0046] In summary, the present invention, based on the gas logging correction, uses the cp5 and wh parameter combination to establish a gas logging identification chart, performs ratio calculation on the alkane component and the total hydrocarbon (TG), and plays a role of standardization; through the application situation, the application effect of the chart is good, the accuracy of oil and gas layer identification is improved, the application scope of gas logging and the accuracy of oil and gas layer identification are improved, and the requirements of oil and gas seismic exploration are met. In addition, it can reduce the expensive cost caused by the original high-pressure physical property experimental analysis, and the actual fluid type can be determined only by gas testing the fluid sample.

[0047] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for determining the fluid properties of oil and gas layers based on gas logging, characterized in that: include: Step 1: Downhole fluid sampling, obtaining fluid sample data through oil and gas layer testing and sampling of exploration wells and production well commissioning; Step 2: Determine the type of the fluid sample, determine the fluid properties of the oil and gas reservoir where the fluid sample is located, and determine the fluid properties of the oil and gas reservoir based on the gas-oil ratio, crude oil density, and heavy component content parameters on the basis of high-pressure physical property experimental analysis; Step 3: Perform gas logging method identification parameters on the same fluid sample, and obtain gas logging parameters wh and cp5; Step 4: Construct a gas measurement identification chart: use wh as the horizontal axis and cp5 as the vertical axis; The gas measurement parameter wh corresponds to the fluid property corresponding to cp5; the gas measurement identification plate is divided into the following areas: dry gas water layer, wet gas water layer, light oil and water layer, oil and water layer, residual oil and water layer, dry gas layer, wet gas layer, light oil layer, general oil layer and residual oil layer; Step 5: Obtain gas testing data of the well to be tested, project the gas testing data to the gas testing identification plate, and determine the fluid type of the oil and gas reservoir of the well to be tested based on the area where the data is located; In step 3, the calculation formulas for wh and cp5 are: wh=C2%+C3%+C4%+C5% In the formula, C1% is the methane content, C2% is the ethane content, C3% is the propane content, C4% is the butane content, and C5% is the pentane content; The methane content is C1%=C1 / Tg*100; the ethane content C2%=C2 / Tg*100; the propane content C3%=C3 / Tg*100; the butane content C4%=C4 / Tg*100; the pentane content C5%=C5 / Tg*100; Tg=C1%+C2%+C3%+C4%+C5%.

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