A method for identifying dolomite reservoirs and a computer-readable storage medium

Abstract

The present invention relates to a method for identifying dolomite reservoirs and a computer-readable storage medium. The method for identifying dolomite reservoirs comprises: 1) collecting compensated neutron, natural gamma, and deep lateral resistivity data; 2) reconstructing compensated neutron, natural gamma, and deep lateral resistivity to obtain an indicator curve; 3) intercepting the indicator curve according to the threshold value of the indicator curve in the region; 4) the position corresponding to the intercepted indicator curve is the dolomite reservoir. The computer-readable storage medium stores a program for implementing the method for identifying dolomite reservoirs, and implements the steps of data acquisition and processing in the method for identifying dolomite reservoirs.

Description

Technical Field

[0001] The present invention relates to a method for identifying dolomite reservoirs, belonging to the technical field of geological exploration of oil and gas reservoirs in dolomite reservoirs. Background Art

[0002] Dolomite is a sedimentary carbonate rock. Carbonate reservoirs are widely distributed in China with rich reserves and great potential for increasing reserves and production. During the exploration and development of dolomite reservoirs in the Ma 5 section, effective and accurate reservoir identification is an important task in oil and gas reservoir exploration. When identifying dolomite reservoirs, conventional methods mostly use five logging curves, namely natural gamma, acoustic travel time, total hydrocarbon in gas logging, compensated neutron, and deep lateral resistivity, as well as porosity, permeability, and gas saturation calculated from natural gamma, acoustic travel time, and deep lateral resistivity to determine the location of reservoir development. However, this method requires comprehensive utilization of multiple logging curve data and the establishment of calculation formulas for porosity, permeability, and gas saturation. The calculation process requires too many logging curves and is complex.

[0003] The patent document with publication number CN111751905A discloses a method for identifying the effectiveness of carbonate reservoirs based on a rock triple porosity model. This method first calculates porosity φ N , porosity φ D , φ b using compensated density, compensated neutron, and acoustic travel time. Then, using φ N and φ D to calculate the total porosity φ T . Then, based on the total porosity φ T and acoustic porosity φ b , three porosities of the carbonate rock are obtained, namely connected fracture-vug porosity φ2, unconnected fracture-vug porosity φ nc , and matrix porosity φ m . According to the total porosity φ T and connected fracture-vug porosity φ2, unconnected fracture-vug porosity φ n c, and matrix porosity φ m , the formation cementation index m is obtained; according to the sum of the connected fracture-vug porosity φ2 and the unconnected fracture-vug porosity φ nc , the secondary porosity is obtained. The effectiveness of the reservoir is quantitatively judged through the standard graph of the ratio BZ of the secondary porosity to the total porosity and the cementation index m. When the ratio BZ of the secondary porosity to the total porosity is greater than 0.02 and the cementation index m is between 1 and 2.18, the reservoir is determined to be effective and belongs to the productive layer. Although the present invention can achieve the determination of the reservoir, this method requires a large amount of calculation process and is relatively complex to implement. Summary of the Invention

[0004] The objective of the present invention is to provide a method for identifying dolomite reservoirs and a computer-readable storage medium, so as to solve the problems of excessive demand for logging curve data and complex calculation process in the process of identifying dolomite reservoirs.

[0005] To achieve the above objective, the solution of the present invention includes:

[0006] A method for identifying dolomite reservoirs of the present invention, the method for identifying dolomite reservoirs includes:

[0007] 1) Collect compensated neutron, natural gamma, and deep lateral resistivity data;

[0008] 2) Substitute the compensated neutron, natural gamma, and deep lateral resistivity into the reconstruction formula to obtain an indicator curve;

[0009] 3) Intercept the indicator curve according to the indicator curve threshold value of the region where it is located;

[0010] 4) The depth corresponding to the intercepted indicator curve is the dolomite reservoir;

[0011] The method for obtaining the indicator curve threshold value is as follows:

[0012] a) Collect logging data of the region where it is located, and the logging data includes: deep lateral resistivity, acoustic travel time, compensated neutron, gas logging total hydrocarbon, natural gamma value;

[0013] b) Substitute the compensated neutron curve, natural gamma curve, and deep lateral resistivity data into the reconstruction formula to obtain an indicator curve;

[0014] c) Determine the development position of the dolomite reservoir according to the natural gamma, deep lateral resistivity, compensated density, gas logging total hydrocarbon, and acoustic travel time curves;

[0015] d) Compare the development position of the dolomite reservoir with the indicator curve, and retain the part of the indicator curve corresponding to the reservoir development position. The minimum value of the part of the indicator curve is the above-mentioned indicator curve threshold value.

[0016] The beneficial effect of doing so is: superimpose the indicator curve with the parameter curves for routinely judging the reservoir development position to determine the threshold value, and then better determine the development position of the entire Majiagou Formation Member 5 reservoir through the threshold value. Solve the problems of many logging curves required for identifying the dolomite reservoir in the Majiagou Formation Member 5 and complex calculation process, and simply and quickly judge the development position of the dolomite reservoir in the Majiagou Formation Member 5, providing effective support for the exploration and development of oil and gas layers in dolomite reservoirs.

[0017] Further, in step 2), the reconstruction formula is:

[0018]

[0019] Where A is the indicator curve, CNL is the compensated neutron parameter, GR is the natural gamma curve parameter, and LLD is the deep lateral resistivity parameter.

[0020] Further, in step d), the method of comparing the development position of the dolomite reservoir with the indicator curve is overlay display.

[0021] The beneficial effect of doing this is: obtaining the threshold value of the indicator curve more straightforwardly and clearly through overlay display.

[0022] Further, a computer-readable storage medium for identifying a dolomite reservoir, characterized in that the storage medium stores instructions capable of implementing the following method:

[0023] 1) Collect compensated neutron, natural gamma, and deep lateral resistivity data;

[0024] 2) Substitute the compensated neutron, natural gamma, and deep lateral resistivity into the reconstruction formula to obtain the indicator curve;

[0025] 3) Intercept the indicator curve according to the threshold value of the indicator curve in the area;

[0026] 4) The depth corresponding to the intercepted indicator curve is the dolomite reservoir;

[0027] The method for obtaining the threshold value of the indicator curve is as follows:

[0028] a) Collect well logging data in the area, and the well logging data includes: deep lateral resistivity, acoustic travel time, compensated neutron, gas logging total hydrocarbon, and natural gamma value;

[0029] b) Substitute the compensated neutron curve, natural gamma curve, and deep lateral resistivity data into the reconstruction formula to obtain the indicator curve;

[0030] c) Determine the development position of the dolomite reservoir according to the natural gamma, deep lateral resistivity, compensated density, gas logging total hydrocarbon, and acoustic travel time curves;

[0031] d) Compare the development position of the dolomite reservoir with the indicator curve, and retain the part of the indicator curve corresponding to the reservoir development position. The minimum value of the part of the indicator curve is the above-mentioned threshold value of the indicator curve.

[0032] Further, in step 2), the reconstruction formula is:

[0033]

[0034] Where A is the indicator curve, CNL is the compensated neutron parameter, GR is the natural gamma curve parameter, and LLD is the deep lateral resistivity parameter.

[0035] Further, in step d), the method of comparing the development position of the dolomite reservoir with the indicator curve is superimposed display. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flowchart of a method for identifying a dolomite reservoir according to the present invention;

[0037] Figure 2 is an effect diagram of identifying the development position of a dolomite reservoir according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Method Embodiment:

[0040] As Figure 1 shown, a method for identifying a dolomite reservoir according to the present invention is implemented through the following steps:

[0041] 1) Collect compensated neutron data, natural gamma data, and deep lateral resistivity data;

[0042] 2) Substitute the collected compensated neutron data, natural gamma data, and deep lateral resistivity data into the reconstruction formula to obtain an indicator curve;

[0043] 3) Intercept the indicator curve according to the indicator curve threshold value in the area where the dolomite is located;

[0044] 4) The depth corresponding to the intercepted indicator curve is the dolomite reservoir;

[0045] The method for obtaining the above-mentioned indicator curve threshold value is as follows:

[0046] a) Collect well logging data in the area where the dolomite is located. The well logging data includes: deep lateral resistivity data, acoustic travel time data, compensated neutron data, gas logging total hydrocarbon data, and natural gamma value data;

[0047] b) Substitute the collected compensated neutron data, natural gamma data, and deep lateral resistivity data into the reconstruction formula to obtain an indicator curve;

[0048] c) According to the method in the prior art (such as the method described in CN111751905A), determine the development position of the dolomite reservoir based on the collected natural gamma data, deep lateral resistivity data, compensated density data, gas logging total hydrocarbon data, and acoustic travel time data;

[0049] d) Superimpose and display the development position of the dolomite reservoir obtained according to the prior art and the indicator curve to determine the indicator curve threshold value.

[0050] The concept of the present invention is as follows: for a region, first, according to the well logging data obtained by the prior art, the natural gamma data in the well logging data can reflect the lithology under certain circumstances, the compensated neutron data can reflect the reservoir development status under certain circumstances, and the deep lateral resistivity data can reflect the gas-bearing status of the reservoir under certain circumstances. Therefore, the present invention obtains these three groups of data, namely natural gamma, compensated neutron, and deep lateral resistivity, reconstructs these three groups of data to form an indicator curve, compares the dolomite reservoir position curve obtained by the prior art method with the indicator curve, and intercepts the indicator curve after comparison, retaining the part corresponding to the reservoir position on the indicator curve. The value corresponding to the intercept position is the threshold value.

[0051] For the identification of the dolomite reservoir positions at other locations in this area, only the compensated neutron data, natural gamma data, and deep lateral resistivity data can be collected and reconstructed to obtain an indicator curve, and the indicator curve is intercepted according to the threshold value of the area position obtained above. The position (depth) corresponding to the remaining part after interception is determined as the dolomite reservoir position.

[0052] After obtaining the threshold value for a region by the method of the present invention, for other positions, only the compensated neutron data, natural gamma data, and deep lateral resistivity data need to be collected and reconstructed to identify the dolomite reservoir, which greatly reduces the amount of well logging data collection and calculation, and reduces the complexity of identifying the dolomite reservoir.

[0053] Taking the reservoir of the fifth member of the Majiagou Formation in the Daniudi Gas Field in Ordos as an example, first collect the well logging data of the fifth member of the Majiagou Formation in the Daniudi Gas Field in Ordos: natural gamma data, deep lateral resistivity data, gas logging total hydrocarbon data, compensated neutron data, and acoustic travel time data.

[0054] To better reflect the reservoir development position, the collected compensated neutron (CNL), natural gamma curve (GR), and deep lateral resistivity (LLD) data are reconstructed and processed:

[0055]

[0056] The indicator curve A is obtained.

[0057] The reservoir development position obtained by the prior art is superimposed and displayed with the indicator curve to determine the threshold value of the indicator curve for the developed dolomite reservoir.

[0058] The method for judging the reservoir development position in the prior art is: using four logging curves, namely, gas logging total hydrocarbon logging curve (QT), natural gamma curve (GR), acoustic transit time (AC), and deep lateral resistivity (LLD), and using three curves, namely, natural gamma curve (GR), acoustic transit time (AC), and deep lateral resistivity (LLD), to calculate porosity (φ), permeability (K), mud content (SH), and gas saturation (Sg), thereby judging the reservoir development position.

[0059] Usually, the lower limits of parameters for reservoir development in the fifth member of the Mawu Formation are: AC ≥ 157μS / M, QT ≥ 2%, 45Ω·m ≤ LLD ≤ 1300Ω·m, Φ ≥ 2.5%, K ≥ 0.03mD, SH ≤ 13.0%, and Sg ≥ 50.0%.

[0060] The method for determining the threshold value of the indicator curve is: superimpose the reservoir development position with the indicator curve and retain the overlapping part of the indicator curve and the reservoir development position. Since the reservoir is discontinuous, the overlapping part is not a continuous curve. In theory, the overlapping positions of the remaining curve segments should correspond to a fixed value, which is the threshold value of the indicator curve.

[0061] If the actual value fluctuates within a small range, those skilled in the art should understand that the curve threshold value can be calculated by using statistical methods, such as a data processing method for calculating the average value, for the data within the floating area.

[0062] The indicator curve is adjusted (cut) according to the threshold value, and only the part that coincides with the reservoir development position is retained. This part is the location where the entire Mawu dolomite reservoir is developed.

[0063] like Figure 2 As shown, the indicator curve of the dolomite of the Mawu section of the Daniudi gas field is superimposed with the parameter curve of the reservoir development position, and the threshold value of the indicator curve is 0.8. The indicator curve is adjusted according to the threshold value, and only the part of the indicator curve greater than 0.8 is retained, and the depth corresponding to the part is the reservoir development position. When the development position of the dolomite of the Mawu section of the Daniudi gas field is identified later, it is not necessary to calculate and determine the dolomite position again using conventional methods. It is only necessary to adjust the indicator curve according to 0.8, which is the reservoir development position of the entire dolomite of the Mawu section of the Daniudi gas field. If it is necessary to identify the development position of dolomite in other areas of the place, it is only necessary to obtain the threshold value of the indicator curve of the place according to the method of the present invention during the first identification, and determine the reservoir development position of the entire dolomite section according to the threshold value of the indicator curve. In the subsequent identification, it is only necessary to use the threshold value of the indicator curve obtained for the first time in combination with the indicator curve to determine the reservoir development position of the entire dolomite of the Mawu section.

[0064] Computer readable storage medium embodiment:

[0065] A computer-readable storage medium stores a program for implementing a method for identifying a dolomite reservoir, and implements the steps of data acquisition and processing in the method for identifying a dolomite reservoir.

[0066] The medium referred to in this embodiment is a programmable data processing device storing computer program instructions. The above medium may also be one or more computer-readable storage media containing computer-usable program code.

Claims

1. A method for identifying dolomite reservoirs, characterized in that, The method for identifying dolomite reservoirs includes: 1) Collect compensated neutron, natural gamma, and deep lateral resistivity data; 2) Substitute the compensated neutron, natural gamma, and deep lateral resistivity into the reconstruction formula to obtain an indicator curve; 3) Intercept the indicator curve according to the indicator curve threshold value in the area; 4) The position corresponding to the intercepted indicator curve is the dolomite reservoir; The method for obtaining the indicator curve threshold value is as follows: a) Collect well logging data in the area, and the well logging data includes: deep lateral resistivity, acoustic travel time, compensated neutron, total hydrocarbon in gas logging, natural gamma value; b) Substitute the compensated neutron curve, natural gamma curve, and deep lateral resistivity data into the reconstruction formula to obtain an indicator curve; c) Determine the development position of the dolomite reservoir according to the natural gamma, deep lateral resistivity, compensated density, total hydrocarbon in gas logging, and acoustic travel time curves; d) Compare the development position of the dolomite reservoir with the indicator curve, and retain the part of the indicator curve corresponding to the reservoir development position. The minimum value of this part is the above-mentioned indicator curve threshold value; In step 2), the reconstruction formula is: ， where A is the indicator curve, CNL is the compensated neutron parameter, GR is the natural gamma curve parameter, and LLD is the deep lateral resistivity parameter.

2. The method for identifying a dolomite reservoir according to claim 1, wherein In step d), the method for comparing the development position of the dolomite reservoir with the indicator curve is overlay display.

3. A computer-readable storage medium for identifying dolomite reservoirs, characterized in that, The storage medium stores instructions that can implement the following method: 1) Collect compensated neutron, natural gamma, and deep lateral resistivity data; 2) Substitute the compensated neutron, natural gamma, and deep lateral resistivity into the reconstruction formula to obtain an indicator curve; 3) Intercept the indicator curve according to the indicator curve threshold value in the area; 4) The depth corresponding to the intercepted indicator curve is the dolomite reservoir; The method for obtaining the indicator curve threshold value is as follows: a) Collect well logging data in the area, and the well logging data includes: deep lateral resistivity, acoustic travel time, compensated neutron, total hydrocarbon in gas logging, natural gamma value; b) Substitute the compensated neutron curve, natural gamma curve, and deep lateral resistivity data into the reconstruction formula to obtain an indicator curve; c) Determine the development position of the dolomite reservoir according to the natural gamma, deep lateral resistivity, compensated density, total hydrocarbon in gas logging, and acoustic travel time curves; d) Compare the development position of the dolomite reservoir with the indicator curve, and retain the part of the indicator curve corresponding to the reservoir development position. The minimum value of this part is the above-mentioned indicator curve threshold value; The reconstruction formula is: , where A is the indicator curve, CNL is the compensated neutron parameter, GR is the natural gamma ray curve parameter, and LLD is the deep laterolog resistivity parameter.

4. The computer-readable storage medium for identifying a dolomite reservoir according to claim 3, wherein In step d), the method for comparing the development position of the dolomite reservoir with the indicator curve is overlay display.

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