CO2 fluid identification method and device

Abstract

The invention belongs to the field of geophysical exploration methods, and discloses a CO2 fluid identification method and device, and the method comprises the steps: obtaining an angle gather data set based on the existing drilling and logging information; carrying out longitudinal wave frequency dispersion gradient calculation to obtain frequency dispersion gradient data under different reservoir fluid conditions; extracting a frequency dispersion gradient value of a pickup horizon I at the top of the main reservoir section; performing unified standardization processing according to the frequency dispersion gradient value to obtain a regional fluid template; based on the regional fluid template, performing pre-stack longitudinal wave velocity dispersion gradient attribute operation on the actual seismic data to obtain a longitudinal wave dispersion gradient body; and calculating a frequency dispersion gradient attribute mean value to obtain a gradient planar graph. The method is suitable for exploration of an early exploration area, can assist in identifying the distribution condition of CO2 fluid in the area, reduces the CO2 drilling risk of subsequent drilling, and improves the exploration benefits of operators.

Description

Technical Field

[0001] This application belongs to the field of geophysical exploration methods, and particularly relates to a method and device for identifying CO 2 fluids. Background Art

[0002] During the domestic and international oil and gas exploration practices, the risk of carbon dioxide accumulation has always troubled petroleum geologists; the research on carbon dioxide accumulation has never stopped. Due to the occurrence characteristics of carbon dioxide under conventional oil reservoir conditions, it is more difficult to identify carbon dioxide. Currently, most of the research on accumulated carbon dioxide focuses on the discussion of the origin of carbon dioxide; the main view is that the accumulated carbon dioxide comes from two directions: mantle origin and crustal origin; by studying the origin and migration channels, indirectly judge the expectation of carbon dioxide accumulation and reduce the risk of petroleum exploration; through geophysical exploration techniques to directly detect and identify carbon dioxide, no obvious effect has been achieved yet. Summary of the Invention

[0003] In order to overcome the defects of the above-mentioned existing technologies, the purpose of this application is to provide a method and device for identifying CO 2 fluids. By establishing reservoir fluid models of different fluids and different saturations, performing oil, gas, and water fluid substitution, and combining AVO (Amplitude Versus Offset) forward modeling, clarify the seismic response characteristics of different fluids; secondly, based on the forward angle gather data set, calculate the longitudinal wave dispersion gradient to obtain the dispersion gradient data under different reservoir fluid conditions, make a regional fluid template, and clarify the CO 2 dispersion gradient characteristics; finally, perform pre-stack longitudinal wave velocity dispersion gradient attribute calculation on the actual seismic data, calibrate the obtained attributes in combination with the regional fluid template, calculate the mean value of the dispersion gradient attributes, obtain the gradient plane map, and finally realize the identification of CO 2 .

[0004] To achieve the above purpose, this application provides the following technical solutions:

[0005] A method for identifying CO 2 fluids, comprising:

[0006] Obtaining an angle gather data set based on existing well logging data;

[0007] Using the angle gather data set to calculate the longitudinal wave dispersion gradient to obtain the dispersion gradient data under different reservoir fluid conditions;

[0008] According to the dispersion gradient data, pick up horizon I at the top of the main reservoir section, and then extract the dispersion gradient value of horizon I;

[0009] According to the dispersion gradient values, trend curves are generated respectively for the water saturation of different fluids, and unified standardization processing is carried out to obtain a regional fluid template;

[0010] Based on the regional fluid template, pre-stack P-wave velocity dispersion gradient attribute calculation is performed on the actual seismic data to obtain a P-wave dispersion gradient volume;

[0011] According to the reservoir thickness, corresponding time windows are opened downward along the P-wave dispersion gradient volume to calculate the mean value of the dispersion gradient attribute, and a gradient plan view is obtained.

[0012] Furthermore, the existing drilling well logging data includes acoustic travel time curves, density curves, mineral composition curves, and fluid content curves.

[0013] Furthermore, based on the existing drilling well logging data, an angle gather data set is obtained, including:

[0014] Based on the existing drilling well logging data, elastic parameters of the reservoir under different fluid fillings are calculated and elastic curves are generated;

[0015] Based on the elastic curves, AVO forward modeling is carried out to generate water-CO 2 , water-natural gas and water-oil two-phase fluid reservoir models and a reservoir model containing single-phase fluid, and corresponding AVO forward angle gather data sets are generated.

[0016] Furthermore, the elastic curves include Vp curves, Vs curves, and Den curves.

[0017] Furthermore, the angle range of the angle gather data set is 0 - 45°, and the range of different water saturations is 10% - 90%.

[0018] Furthermore, using the angle gather data set to calculate the P-wave dispersion gradient, dispersion gradient data under different reservoir fluid conditions are obtained, including:

[0019] Using the angle gather data set, data at multiple preset angles are extracted, arranged in order to form near, middle, and far trace gathers, and P-wave dispersion gradient calculation is carried out to obtain dispersion gradient data under different reservoir fluid conditions.

[0020] Furthermore, according to the dispersion gradient values, trend curves are generated respectively for the water saturation of different fluids, and unified standardization processing is carried out to obtain a regional fluid template, including:

[0021] According to the dispersion gradient values, trend curves are generated respectively for the water saturation of natural gas, oil, and CO 2 , and unified standardization processing is carried out to obtain a regional fluid template.

[0022] In a second aspect, the present application discloses a CO 2Device for fluid identification, comprising:

[0023] An angular gather data set acquisition unit, configured to acquire an angular gather data set based on existing drilling logging data;

[0024] A dispersion gradient data acquisition unit, configured to perform P-wave dispersion gradient calculation using the angular gather data set to obtain dispersion gradient data under different reservoir fluid conditions;

[0025] A P-wave dispersion gradient volume acquisition unit, configured to perform pre-stack P-wave velocity dispersion gradient attribute operation on actual seismic data based on a regional fluid template to obtain a P-wave dispersion gradient volume;

[0026] A gradient plan view acquisition unit, configured to calculate the mean value of the dispersion gradient attribute by opening a corresponding time window downward along the P-wave dispersion gradient volume according to the reservoir thickness to obtain a gradient plan view.

[0027] In a third aspect, the present application discloses an electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for identifying a certain type of fluid when executing the program. 2

[0028] In a third aspect, the present application discloses a computer-readable storage medium, on which a computer program is stored, and the computer program implements the steps of the above-mentioned method for identifying a certain type of fluid when executed by a processor. 2

[0029] Technical effects and advantages of the present application:

[0030] In the present application, a reservoir fluid model with different fluids and different saturations is established, fluid substitution of oil, gas, and water is performed, and combined with AVO (Amplitude Versus Offset) forward modeling to obtain an angular gather data set; secondly, P-wave dispersion gradient calculation is performed based on the angular gather data set to obtain dispersion gradient data under different reservoir fluid conditions, a regional fluid template is made to clarify the characteristics of the dispersion gradient; finally, pre-stack P-wave velocity dispersion gradient attribute operation is performed on actual seismic data, the obtained attributes are calibrated in combination with the regional fluid template, the mean value of the dispersion gradient attribute is calculated to obtain a gradient plan view, and finally the identification of a certain type of fluid is realized. 2 2

[0031] The method of the present application is applicable to exploration areas in the early stage of exploration, can assist in identifying the distribution status of a certain type of fluid in the area, reduce the drilling encounter risk in subsequent drilling, and improve the exploration efficiency of operators. 2 2

[0032] Other features and advantages of the present application will be described in the following specification, and in part will be obvious from the specification, or can be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the structures pointed out in the specification, claims and drawings. Description of the Drawings

[0033] Figure 1 A CO 2 Flowchart of the method for fluid identification

[0034] Figure 2 Model after fluid substitution in the reservoir development section of the embodiment

[0035] Figure 3 Schematic diagram of forward AVO simulation of the AVO gather in the embodiment

[0036] Figure 4 Forward AVO angle gather of different fluids under different saturation conditions in the embodiment

[0037] Figure 5 Reservoir longitudinal wave dispersion gradient response under different saturation fluid fillings in the embodiment

[0038] Figure 6 Data picking profile of the reservoir longitudinal wave dispersion gradient response in the embodiment

[0039] Figure 7 Regional fluid template M in the embodiment

[0040] Figure 8 Longitudinal wave dispersion gradient volume P calculated from the actual seismic data in the embodiment

[0041] Figure 9 Gradient plan view in the embodiment Detailed Description of the Embodiments

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0043] As Figure 1 shown, the present application provides a CO 2 method for fluid identification, including:

[0044] Obtaining an angle gather data set based on existing drilling logging data;

[0045] Calculate the longitudinal wave dispersion gradient using the angle gather dataset to obtain the dispersion gradient data under different reservoir fluid conditions;

[0046] Based on the dispersion gradient data, pick the horizon I at the top of the main reservoir section, and then extract the dispersion gradient value of horizon I;

[0047] Based on the dispersion gradient value, generate trend curves for the water saturation of different fluids respectively, and perform unified standardization processing to obtain the regional fluid template;

[0048] Perform pre-stack longitudinal wave velocity dispersion gradient attribute calculation on the actual seismic data based on the regional fluid template to obtain the longitudinal wave dispersion gradient volume;

[0049] According to the reservoir thickness, open corresponding time windows downward along the longitudinal wave dispersion gradient volume to calculate the mean value of the dispersion gradient attribute, and obtain the gradient plan view.

[0050] In some embodiments of the present application, the existing drilling well logging data includes acoustic travel time curve, density curve, mineral composition curve and fluid content curve.

[0051] In some embodiments of the present application, obtaining the angle gather dataset based on the existing drilling well logging data includes:

[0052] Calculate the elastic parameters of the reservoir under different fluid fillings based on the existing drilling well logging data and generate elastic curves;

[0053] Perform AVO forward modeling based on the elastic curves to generate water-CO 2 , water-natural gas and water-oil two-phase fluid reservoir models and reservoir models containing single-phase fluids under different water saturation conditions, and generate corresponding AVO forward angle gather datasets.

[0054] In some embodiments of the present application, the elastic curves include Vp curve, Vs curve and Den curve.

[0055] In some embodiments of the present application, the angle range of the angle gather dataset is 0-45°, and the range of different water saturations is 10%-90%.

[0056] In some embodiments of the present application, calculating the longitudinal wave dispersion gradient using the angle gather dataset to obtain the dispersion gradient data under different reservoir fluid conditions includes:

[0057] Using the angle gather dataset, extract data at multiple preset angles, such as data at 5°, 20° and 35°, arrange them in order to form near, middle and far trace gathers, and perform longitudinal wave dispersion gradient calculation to obtain the dispersion gradient data under different reservoir fluid conditions.

[0058] In some embodiments of the present application, trend curves are generated for the water saturation of different fluids respectively according to the dispersion gradient value, and unified standardization processing is performed to obtain a regional fluid template, including:

[0059] According to the dispersion gradient value, trend curves are generated for the water saturation of natural gas, oil and CO 2 , and unified standardization processing is performed to obtain a regional fluid template.

[0060] In a second aspect, the present application also discloses a device for CO 2 fluid identification, including:

[0061] An angular gather data set acquisition unit, configured to acquire an angular gather data set based on existing well logging data;

[0062] A dispersion gradient data acquisition unit, configured to perform longitudinal wave dispersion gradient calculation using the angular gather data set to obtain dispersion gradient data under different reservoir fluid conditions;

[0063] A longitudinal wave dispersion gradient volume acquisition unit, configured to perform pre-stack longitudinal wave velocity dispersion gradient attribute calculation on actual seismic data based on the regional fluid template to obtain a longitudinal wave dispersion gradient volume;

[0064] A gradient plan view acquisition unit, configured to calculate the mean value of the dispersion gradient attribute by opening a corresponding time window downward along the longitudinal wave dispersion gradient volume according to the reservoir thickness to obtain a gradient plan view.

[0065] In a third aspect, the present application also discloses an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the above-mentioned method for CO 2 fluid identification are implemented.

[0066] In a fourth aspect, the present application also discloses a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method for CO 2 fluid identification are implemented.

[0067] To better illustrate the present solution, the following embodiments are also provided.

[0068] Embodiment

[0069] Step 1: Perform fluid substitution using curves such as the acoustic travel time curve, density curve, and mineral composition of existing well logging data, calculate the elastic parameters of the reservoir under different fluid filling conditions, and generate corresponding elastic curves; Figure 2For the comparison of the differences in the longitudinal and transverse wave velocities and density curves after different fluid replacements in the reservoir development section, the porosity curve is on the far right. The vertical axis of the attached figure represents the reservoir depth, and the horizontal axis indicates the dynamic range of each curve. It can be seen that the longitudinal wave velocity and density reach their maximum values when the reservoir contains water, and the difference in the transverse wave velocity is relatively small under different fluid fillings.

[0070] Step 2: Based on Step 1, select the target layer range of 5300 - 5800 m, conduct AVO forward modeling for the target layer range, and synthesize the gather records using the Zoeppritz equation according to the elastic curves. Figure 3 For the AVO gather forward modeling Figure 3 The left curves in the figure are the original longitudinal and transverse wave velocities, density, and the corresponding Poisson's ratio and impedance curves. The right sides are respectively the AVO forward angle gather, the synthetic record of vertical incidence, and the actual gather data of the well-side trace. The left vertical axis represents time, and the right indicates the depth of the target layer. The horizontal axis of each curve indicates the dynamic range of the curve. The horizontal axis of the AVO forward gather represents different incident angles, and the horizontal axis of the actual gather data represents the offset size.

[0071] Step 3: Based on Steps 1 and 2, generate the AVO forward angle gather data sets S of the water - CO 2 , water - natural gas, and water - oil two - phase fluid reservoir models and the reservoir model containing single - phase fluid under different water saturation conditions. Figure 4 For the AVO forward angle gather of different fluids under different saturations, the vertical axis of the AVO forward angle gather is time, the horizontal axis is the incident angle, the angle range is 0 - 45 degrees, the angle interval is 5, the water saturation range is 10% - 90%, and the interval is 10%.

[0072] Step 4: According to the angle gather data set S generated in Step 3, extract the data at 5°, 20°, and 35° respectively, arrange them in a certain order to form near, middle, and far trace gathers, and calculate the longitudinal wave dispersion gradient to obtain the dispersion gradient data D under different reservoir fluid conditions. Figure 5 For the longitudinal wave dispersion gradient response of the reservoir filled with fluids of different saturations, the horizontal axis is the water saturation of 10% - 90%, and the color indicates the dispersion gradient value.

[0073] Step 5: Based on the dispersion gradient data D calculated in Step 4, pick the horizon I at the top of the main reservoir section, and then extract the dispersion gradient value V of horizon I, as Figure 6 shown Figure 6 For the picking profile of the longitudinal wave dispersion gradient response data of the reservoir, the upper vertical axis represents time, the horizontal axis represents water saturation, the waveform amplitude indicates the longitudinal wave dispersion gradient value, and the lower part shows the picking gradient result of the target layer, showing the characteristic that the dispersion gradient gradually weakens with the increase of water saturation.

[0074] Step 6: Based on the dispersion gradient value V obtained in Step 5, generate trend curves for the water saturation of different fluids (such as natural gas, oil, CO 2 ), and perform unified standardization processing to obtain the regional fluid template M, as Figure 7 shown, Figure 7 The vertical axis indicates the normalized gradient value of different fluid dispersions, the horizontal axis indicates the fluid water saturation, and the curve represents the longitudinal wave dispersion gradient value of different fluids under different water saturation conditions.

[0075] Step 7: Based on the regional fluid template M, perform dispersion gradient attribute calculation on the actual seismic data to obtain the longitudinal wave dispersion gradient volume P, as Figure 8 shown, Figure 8 Showing the longitudinal wave dispersion gradient profile, the vertical axis represents time, and the horizontal axis indicates the gradient attribute trace; the black dashed line in the figure represents the top surface T of the target reservoir, the bright color represents the high value of the dispersion gradient, and the gray color represents the relatively low value of the dispersion gradient. The profile shows the lateral variation of the longitudinal wave dispersion gradient caused by fluid differences.

[0076] Step 8: According to the reservoir thickness, open a corresponding time window downward along the longitudinal wave dispersion gradient volume P to calculate the average value of the dispersion gradient attribute, and obtain the gradient plan view, as Figure 9 shown. According to the regional fluid template M obtained in Step 6, combined with the structural drilling situation, after normalization, it shows that the middle part of the structure is a high-dispersion gradient CO 2 fluid, and the bright-colored annular fluid in the wing is predicted to be an oil-water mixed fluid.

[0077] Finally, it should be noted that the above are only the preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for identifying a CO 2 fluid It is characterized in that it includes: acquiring an angle gather data set based on existing drilling and logging data; calculating the longitudinal wave dispersion gradient by using the angle gather data set to obtain dispersion gradient data under different reservoir fluid conditions; selecting the top picking horizon I of the main reservoir section according to the dispersion gradient data, and then extracting the dispersion gradient value of horizon I; generating trend curves for the water saturation of different fluids respectively according to the dispersion gradient value, and performing unified standardization processing to obtain a regional fluid template; performing pre-stack longitudinal wave velocity dispersion gradient attribute operation on actual seismic data based on the regional fluid template to obtain a longitudinal wave dispersion gradient volume; calculating the mean value of the dispersion gradient attribute by opening a corresponding time window downward along the longitudinal wave dispersion gradient volume according to the reservoir thickness to obtain a gradient plan view.

2. A method for identifying a CO 2 fluid, It is characterized in that the existing drilling and logging data includes acoustic travel time curve, density curve, mineral composition curve and fluid content curve.

3. A method for identifying a CO 2 fluid, It is characterized in that the acquiring of the angle gather data set based on existing drilling and logging data includes: calculating the elastic parameters of the reservoir under different fluid fillings based on existing drilling and logging data and generating elastic curves; Based on the elastic curve, AVO forward modeling is carried out to generate water-CO 2 , water-natural gas and water-oil two-phase fluid reservoir models and a reservoir model containing single-phase fluid, and the corresponding AVO forward angle gather data sets are generated.

4. A method for identifying a CO 2 fluid, It is characterized in that the elastic curves include Vp curve, Vs curve and Den curve.

5. A method for identifying a CO 2 fluid, It is characterized in that the angle range of the angle gather data set is 0 - 45°, and the range of different water saturations is 10% - 90%.

6. A method for identifying a CO 2 fluid, It is characterized in that the calculating of the longitudinal wave dispersion gradient by using the angle gather data set to obtain dispersion gradient data under different reservoir fluid conditions includes: using the angle gather data set, extracting data of multiple preset angles, arranging them in order to form near, middle and far trace gathers, and performing longitudinal wave dispersion gradient calculation to obtain dispersion gradient data under different reservoir fluid conditions.

7. A method for identifying a CO 2 fluid, It is characterized in that the generating of trend curves for the water saturation of different fluids respectively according to the dispersion gradient value and performing unified standardization processing to obtain a regional fluid template includes: According to the dispersion gradient value, trend curves are respectively generated for the water saturation of natural gas, oil, and CO 2 , and unified standardization processing is carried out to obtain a regional fluid template.

8. A CO 2 fluid identification device, It is characterized in that it includes: an angle gather data set obtaining unit for acquiring an angle gather data set based on existing drilling and logging data; a dispersion gradient data obtaining unit for calculating the longitudinal wave dispersion gradient by using the angle gather data set to obtain dispersion gradient data under different reservoir fluid conditions; a longitudinal wave dispersion gradient volume obtaining unit for performing pre-stack longitudinal wave velocity dispersion gradient attribute operation on actual seismic data based on the regional fluid template to obtain a longitudinal wave dispersion gradient volume; a gradient plan view obtaining unit for calculating the mean value of the dispersion gradient attribute by opening a corresponding time window downward along the longitudinal wave dispersion gradient volume according to the reservoir thickness to obtain a gradient plan view.

9. An electronic device, including a memory, a processor and a computer program stored on the memory and executable on the processor, It is characterized in that When the processor executes the program, it implements the steps of a method for identifying a CO fluid according to any one of claims 1-7. 2 ​ 10. A computer-readable storage medium, on which a computer program is stored, It is characterized in that When the computer program is executed by a processor, it implements the steps of a method for identifying a CO 2 fluid as described in any one of claims 1-7. 2 fluid.

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