Method for establishing interpretation and evaluation chart of unconventional reservoir based on hydrocarbon ratio

Abstract

The invention relates to the technical field of interpretation chart establishment, in particular to a method for establishing an unconventional reservoir interpretation and evaluation chart based on hydrocarbon ratios, which comprises the following steps of: obtaining a hydrocarbon ratio parameter combination of a well put into production in a research area; determining an oil-water boundary judgment parameter combination based on the hydrocarbon ratio parameter combination and the total hydrocarbon rise coefficient of the well put into production; based on the oil-water boundary determination parameter combination, constructing an oil-water identification chart corresponding to the target reservoir in the research area; obtaining an oil-water boundary judgment parameter combination of a to-be-measured well in the research area; and based on the oil-water boundary determination parameter combination interpretation oil-water identification chart of the to-be-logged well, drawing an unconventional reservoir interpretation evaluation chart. According to the method, oil-water boundary judgment parameters are constructed by utilizing a gas logging technology and a hydrocarbon ratio method, key parameters are screened out by utilizing a gas logging hydrocarbon ratio optimization method, unconventional reservoir interpretation charts and standards are established, the accurate recognition rate of unconventional reservoirs is improved, and technical guarantee is provided for oilfield exploration and development and optimal and fast drilling.

Description

Technical Field

[0001] This invention relates to the field of interpretation chart creation technology, and is a method for creating interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios. Background Technology

[0002] As oil exploration and development deepen, reservoirs are gradually shifting from conventional sandstone reservoirs to unconventional reservoirs such as tight rocks and shale, exhibiting complexity and concealment. Currently, the discovery, interpretation, and evaluation of unconventional reservoirs face several challenges: First, near-bit resistivity and natural gamma ray changes are minimal, making accurate identification and interpretation of low-resistivity oil layers difficult. Second, conventional logging interpretation of oil-water layers in such reservoirs is challenging and slow. Third, the logging response characteristics of these oil layers are not significantly different from those of water layers, often leading to misidentification. Fourth, when high-resistivity and low-resistivity oil layers coexist in the same interval, they are more easily overlooked. Fifth, objective factors such as drilling fluid intrusion and the conductivity of the rock skeleton can also cause low resistivity in oil layers, making them appear equivalent to water layers. Any of these reasons can lead to missed reservoir intervals or increase the difficulty of interpretation and evaluation. Summary of the Invention

[0003] This invention provides a method for establishing interpretation and evaluation charts of unconventional reservoirs based on hydrocarbon ratios, which overcomes the shortcomings of the prior art and can effectively solve the problem of low accuracy in identifying existing unconventional reservoirs.

[0004] One of the technical solutions of this invention is achieved through the following measures: a method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios, comprising the following steps:

[0005] Obtain the hydrocarbon ratio parameter combination of the wells already in production within the study area;

[0006] The combination of parameters for determining the oil-water boundary is determined based on the combination of hydrocarbon ratio parameters and the total hydrocarbon rise coefficient of the wells already in production.

[0007] Based on the combination of oil-water boundary determination parameters, an oil-water identification map corresponding to the target reservoir in the study area is constructed.

[0008] Obtain the combination of parameters for determining the oil-water boundary of the wells to be logged within the study area;

[0009] Based on the combination of oil-water boundary determination parameters of the well to be logged, interpret the oil-water identification chart and draw the interpretation and evaluation chart of unconventional reservoirs;

[0010] The hydrocarbon ratio parameter combination includes a first hydrocarbon ratio parameter and a second hydrocarbon ratio parameter, and the oil-water boundary determination parameter combination includes a first oil-water boundary determination parameter and a second oil-water boundary determination parameter.

[0011] The above-mentioned combinations of hydrocarbon ratio parameters for wells already in production within the study area include:

[0012] Based on the C1, C2, C3, C4 and C5 data from the logging gas data of the wells that have been put into production, the hydrocarbon ratio parameter database is obtained by alternating and non-repeating combinations, where C4 includes iC4 and nC4, and C5 includes iC5 and nC5.

[0013] The correlation between each hydrocarbon ratio parameter in the hydrocarbon ratio parameter database and changes in reservoir fluid properties is arranged from high to low.

[0014] Select the two hydrocarbon ratio parameters with the highest correlation as the hydrocarbon ratio parameter combination.

[0015] The above-mentioned combination of parameters for determining the oil-water boundary, based on the hydrocarbon ratio parameter combination and the total hydrocarbon increase coefficient of the wells already in production, includes: the oil-water boundary determination parameters calculated according to the following formula:

[0016] F1 = Q1K

[0017] F2=Q2K

[0018] Where Q1 is the first hydrocarbon ratio parameter, Q2 is the second hydrocarbon ratio parameter; F1 is the first oil-water boundary determination parameter, F2 is the second oil-water boundary determination parameter, and K is the total hydrocarbon increase coefficient.

[0019] The above-mentioned total hydrocarbon increase coefficient K is obtained according to the following formula:

[0020] K = 1 - (T1 / T2) / 100

[0021] Where K is the total hydrocarbon increase coefficient; T1 is the total hydrocarbon outlier; and T2 is the total hydrocarbon base value.

[0022] The above-mentioned combination of oil-water boundary determination parameters constructs an oil-water identification map corresponding to the target reservoir in the study area, including:

[0023] Using the first oil-water boundary determination parameter as the abscissa of the oil-water identification map and the second oil-water boundary determination parameter as the ordinate of the oil-water identification map, an oil-water identification map corresponding to the target reservoir in the study area is constructed.

[0024] The values ​​of the first oil-water boundary determination parameter and the second oil-water boundary determination parameter indicate that the fluid type of the target reservoir in the study area is the same as the fluid type of the reservoir where the first oil-water boundary determination parameter and the second oil-water boundary determination parameter are located.

[0025] The fluid types include oil reservoirs, oil-bearing water reservoirs, and water reservoirs.

[0026] The aforementioned unconventional reservoirs include tight sandstone reservoirs, metamorphic rocks, shale reservoirs, and low-resistivity reservoirs.

[0027] The aforementioned combinations of hydrocarbon ratio parameters for tight sandstone reservoirs include iC4 / nC5 and iC4 / nC4.

[0028] The hydrocarbon ratio parameter combinations of the above-mentioned metamorphic rock reservoirs include C1 / C4 and C1 / nC5.

[0029] The aforementioned hydrocarbon ratio parameter combinations for shale reservoirs include iC4 / nC4 and C4 / C3.

[0030] The hydrocarbon ratio parameter combinations for the aforementioned low-resistivity reservoirs include C1 / C2 and (C4+C5) / C3.

[0031] This invention utilizes gas logging technology and hydrocarbon ratio method to construct parameters for determining the oil-water boundary. It also uses the gas logging hydrocarbon ratio optimization method to screen out key parameters, establish interpretation charts and standards for unconventional reservoirs, improve the accuracy of unconventional reservoir identification, and provide technical support for oilfield exploration and development and efficient drilling. Attached Figure Description

[0032] Appendix Figure 1 This is a schematic diagram of the interpretation and evaluation of tight sandstone reservoirs according to the present invention.

[0033] Appendix Figure 2 This is a schematic diagram of the interpretation and evaluation of metamorphic rock reservoirs according to the present invention.

[0034] Appendix Figure 3 This is a schematic diagram of the interpretation and evaluation of shale reservoirs according to the present invention.

[0035] Appendix Figure 4 This is a schematic diagram of the wells already in production and those currently being drilled within the study area in Embodiment 11 of the present invention.

[0036] Appendix Figure 5 This is a schematic diagram of the total hydrocarbon outlier replacement and total hydrocarbon base value taking points in Example 11 of the present invention.

[0037] Appendix Figure 6 This is a schematic diagram of the interpretation and evaluation of low-resistivity reservoirs in Embodiment 11 of the present invention. Detailed Implementation

[0038] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0039] The present invention will be further described below with reference to embodiments:

[0040] Example 1: The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios includes the following steps:

[0041] Obtain the hydrocarbon ratio parameter combination of the wells already in production within the study area;

[0042] The combination of parameters for determining the oil-water boundary is determined based on the combination of hydrocarbon ratio parameters and the total hydrocarbon rise coefficient of the wells already in production.

[0043] Based on the combination of oil-water boundary determination parameters, an oil-water identification map corresponding to the target reservoir in the study area is constructed.

[0044] Obtain the combination of parameters for determining the oil-water boundary of the wells to be logged within the study area;

[0045] Based on the combination of oil-water boundary determination parameters of the well to be logged, interpret the oil-water identification chart and draw the interpretation and evaluation chart of unconventional reservoirs;

[0046] The hydrocarbon ratio parameter combination includes a first hydrocarbon ratio parameter and a second hydrocarbon ratio parameter, and the oil-water boundary determination parameter combination includes a first oil-water boundary determination parameter and a second oil-water boundary determination parameter.

[0047] In this invention, the wells that have been put into production and the wells to be tested are located within the same oil and gas reservoir trap and the same stratigraphic trap.

[0048] Example 2: As an optimization of the above example, a combination of hydrocarbon ratio parameters for wells already in production within the study area was obtained, including:

[0049] Based on the C1, C2, C3, C4 and C5 data from the logging gas data of the wells that have been put into production, the hydrocarbon ratio parameter database is obtained by alternating and non-repeating combinations, where C4 includes iC4 and nC4, and C5 includes iC5 and nC5.

[0050] The correlation between each hydrocarbon ratio parameter in the hydrocarbon ratio parameter database and changes in reservoir fluid properties is arranged from high to low.

[0051] Select the two hydrocarbon ratio parameters with the highest correlation as the hydrocarbon ratio parameter combination.

[0052] Example 3: As an optimization of the above examples, the oil-water boundary determination parameter combination is determined based on the hydrocarbon ratio parameter combination and the total hydrocarbon increase coefficient of the wells already in production, including: calculating the oil-water boundary determination parameters according to the following formula:

[0053] F1 = Q1K

[0054] F2=Q2K

[0055] Where Q1 is the first hydrocarbon ratio parameter, Q2 is the second hydrocarbon ratio parameter; F1 is the first oil-water boundary determination parameter, F2 is the second oil-water boundary determination parameter, and K is the total hydrocarbon increase coefficient.

[0056] Hydrocarbon ratio Where Xa is any combination of C1, C2, C3, C4 (including iC4 and nC4), and C5 (including iC5 and nC5); Xn is any remaining combination after Xa has been selected. This yields a total of 125 hydrocarbon ratio parameters. These are then used as the two hydrocarbon ratio parameters with the highest correlation to changes in reservoir fluid properties in the hydrocarbon ratio parameter database: the first hydrocarbon ratio parameter and the second hydrocarbon ratio parameter.

[0057] Example 4: As an optimization of the above examples, the total hydrocarbon increase coefficient K is obtained according to the following formula:

[0058] K = 1 - (T1 / T2) / 100

[0059] Where K is the total hydrocarbon increase coefficient; T1 is the total hydrocarbon outlier; and T2 is the total hydrocarbon base value.

[0060] Example 5: As an optimization of the above examples, an oil-water identification map corresponding to the target reservoir in the study area is constructed based on the combination of oil-water boundary determination parameters, including:

[0061] Using the first oil-water boundary determination parameter as the abscissa of the oil-water identification map and the second oil-water boundary determination parameter as the ordinate of the oil-water identification map, an oil-water identification map corresponding to the target reservoir in the study area is constructed.

[0062] The values ​​of the first oil-water boundary determination parameter and the second oil-water boundary determination parameter indicate that the fluid type of the target reservoir in the study area is the same as the fluid type of the reservoir where the first oil-water boundary determination parameter and the second oil-water boundary determination parameter are located.

[0063] The fluid types include oil reservoirs, oil-bearing water reservoirs, and water reservoirs.

[0064] Example 6: As an optimization of the above examples, unconventional reservoirs include tight sandstone reservoirs, metamorphic rocks, shale reservoirs, and low-resistivity reservoirs.

[0065] Example 7: As an optimization of the above examples, the hydrocarbon ratio parameter combination for tight sandstone reservoirs includes iC4 / nC5 and iC4 / nC4. A schematic diagram of the interpretation and evaluation chart for tight sandstone reservoirs is shown below. Figure 1 .

[0066] Example 8: As an optimization of the above examples, the hydrocarbon ratio parameter combination for the metamorphic reservoir includes C1 / C4 and C1 / nC5. A schematic diagram of the interpretation and evaluation chart for the metamorphic reservoir is shown below. Figure 2 .

[0067] Example 9: As an optimization of the above examples, the hydrocarbon ratio parameter combination for shale reservoirs includes iC4 / nC4 and C4 / C3. A schematic diagram of the interpretation and evaluation chart for metamorphic reservoirs is shown below. Figure 3 .

[0068] Example 10: As an optimization of the above examples, the hydrocarbon ratio parameter combination for low-resistivity reservoirs includes C1 / C2 and (C4+C5) / C3.

[0069] Gas logging data directly reflects the oil-bearing properties of formations and has a high degree of parameter quantification, offering advantages in identifying unconventional oil-bearing layers. While gas logging component values ​​are generally relatively complete in unconventional oil-bearing layers, some variability still exists. This invention uses gas logging data as a foundation, combining gas logging hydrocarbon ratios and total hydrocarbon rise coefficients to establish an oil-water identification boundary calculation model, establish evaluation parameters, and construct interpretation charts and standards for hydrocarbon ratios during drilling for different unconventional reservoirs, thereby achieving accurate identification of unconventional oil-bearing layers.

[0070] Example 11: Taking the establishment of low-resistivity reservoir maps as an example, the specific implementation of this method for establishing maps for interpreting and evaluating unconventional reservoirs based on hydrocarbon ratios is as follows:

[0071] Select at least 10 completed wells within the area to establish an oil-water identification chart. For example... Figure 4 As shown, this embodiment selects reservoir gas logging data from 11 wells already in production in the study area; the logging data from these 11 wells are C1, C2, C3, C4, and C5 (C4 includes iC4 and nC4, and C5 includes iC5 and nC5), which are alternately combined without repetition, and a preferred hydrocarbon ratio parameter database is selected. From the hydrocarbon ratio parameter database, the C1 / C2 and (C4+C5) / C3 ratios are selected as having the highest correlation with changes in reservoir fluid properties, and therefore are used as key parameters, denoted as the first hydrocarbon ratio parameter Q1 (C1 / C2) and the second hydrocarbon ratio parameter Q2 ((C4+C5) / C3), respectively.

[0072] The total hydrocarbon uplift coefficient K is calculated using K = 1 - (T1 / T2) / 100. In this invention, the total hydrocarbon anomaly is taken as the component value of the group consisting of the highest total hydrocarbon value and the highest C1 value for each layer; the total hydrocarbon base value is taken as the minimum value at the forefront of the anomaly, see... Figure 5 .

[0073] Based on F1 = Q1K and F2 = Q2K, the first oil-water boundary determination parameter F1(C1 / C2) and the second oil-water boundary determination parameter F2((C4+C5) / C3) are calculated, and an oil-water identification chart is drawn. Figure 6 .

[0074] Gas logging data from up to 11 completed wells in the region were calculated and plotted on the oil-water identification chart.

[0075] Based on the reservoir fluid properties reflected in the oil-water identification chart, a threshold range is set:

[0076] The oil zone range is F1≤Y1, and F2≤R1;

[0077] The range of the oil-bearing water zone is Y1 < F1 ≤ Y2 or R1 < (F2 ≤ R2;

[0078] The range of the water zone is F1 > Y2 or F2 > R2;

[0079] Among them, Y1 is the upper limit value of the oil zone of the first oil-water boundary determination parameter; Y2 is the upper limit value of the oil-bearing water zone of the first oil-water boundary determination parameter; R1 is the upper limit value of the oil zone of the second oil-water boundary determination parameter; R2 is the upper limit value of the oil-bearing water zone of the second oil-water boundary determination parameter.

[0080] The oil layer, oil-bearing water layer and water layer are divided according to the above range values ( Figure 6 ), and the values of these two parameters of the well being drilled are put into this chart, and the nature of the fluid is confirmed according to the landing point, so as to realize the establishment of the interpretation and evaluation chart of low-resistivity oil layers based on hydrocarbon ratios.

[0081] To sum up, the present invention uses gas logging technology and hydrocarbon ratio method to optimize the key parameters in the region, establishes the hydrocarbon ratio interpretation charts of different unconventional reservoirs according to the key parameters, establishes the oil-water identification boundary according to the fitting relationship of the charts, takes this chart as the regional standard chart, puts the values of these two key parameters of the new well or the well being drilled into this chart, and confirms the nature of the fluid according to the landing point, realizes the rapid identification of different unconventional reservoirs, solves the existing problems, improves the accurate identification rate of unconventional reservoirs such as low resistivity, and provides technical support for oilfield exploration and development and efficient drilling.

[0082] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effects. Non-essential technical features can be added or subtracted according to actual needs to meet the requirements of different situations.

Claims

1. A method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios, characterized in that... Includes the following steps: Obtain the hydrocarbon ratio parameter combination of the wells already in production within the study area; The combination of parameters for determining the oil-water boundary is determined based on the combination of hydrocarbon ratio parameters and the total hydrocarbon rise coefficient of wells already in production. Based on the combination of oil-water boundary determination parameters, an oil-water identification map corresponding to the target reservoir in the study area is constructed. Obtain the combination of parameters for determining the oil-water boundary of the wells to be logged within the study area; Based on the combination of oil-water boundary determination parameters of the well to be logged, interpret the oil-water identification chart and draw the interpretation and evaluation chart of unconventional reservoirs; The hydrocarbon ratio parameter combination includes a first hydrocarbon ratio parameter and a second hydrocarbon ratio parameter, and the oil-water boundary determination parameter combination includes a first oil-water boundary determination parameter and a second oil-water boundary determination parameter.

2. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to claim 1, characterized in that... Obtain the hydrocarbon ratio parameter combination of the wells already in production within the study area, including: Based on the C1, C2, C3, C4 and C5 data from the logging gas data of the wells that have been put into production, the hydrocarbon ratio parameter database is obtained by alternating and non-repeating combinations, where C4 includes iC4 and nC4, and C5 includes iC5 and nC5. The correlation between each hydrocarbon ratio parameter in the hydrocarbon ratio parameter database and changes in reservoir fluid properties is arranged from high to low. Select the two hydrocarbon ratio parameters with the highest correlation as the hydrocarbon ratio parameter combination.

3. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to claim 1 or 2, characterized in that... The oil-water boundary determination parameter combination is determined based on the hydrocarbon ratio parameter combination and the total hydrocarbon rise coefficient of the wells already in production. This includes: the oil-water boundary determination parameters are calculated according to the following formula: F1 = Q1K F2=Q2K Where Q1 is the first hydrocarbon ratio parameter, Q2 is the second hydrocarbon ratio parameter; F1 is the first oil-water boundary determination parameter, F2 is the second oil-water boundary determination parameter, and K is the total hydrocarbon increase coefficient.

4. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to claim 3, characterized in that... The total hydrocarbon rise coefficient K is obtained according to the following formula: K = 1 - (T1 / T2) / 100 Where K is the total hydrocarbon increase coefficient; T1 is the total hydrocarbon outlier; and T2 is the total hydrocarbon base value.

5. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to any one of claims 1 to 4, characterized in that... Based on the combination of oil-water boundary determination parameters, an oil-water identification map corresponding to the target reservoir in the study area is constructed, including: Using the first oil-water boundary determination parameter as the abscissa of the oil-water identification map and the second oil-water boundary determination parameter as the ordinate of the oil-water identification map, an oil-water identification map corresponding to the target reservoir in the study area is constructed. The values ​​of the first oil-water boundary determination parameter and the second oil-water boundary determination parameter indicate that the fluid type of the target reservoir in the study area is the same as the fluid type of the reservoir where the first oil-water boundary determination parameter and the second oil-water boundary determination parameter are located. The fluid types include oil reservoirs, oil-bearing water reservoirs, and water reservoirs.

6. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to any one of claims 1 to 5, characterized in that... Unconventional reservoirs include tight sandstone reservoirs, metamorphic rocks, shale reservoirs, and low-resistivity reservoirs.

7. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to claim 6, characterized in that... The hydrocarbon ratio parameter combinations for tight sandstone reservoirs include iC4 / nC5 and iC4 / nC4.

8. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to claim 6 or 7, characterized in that... The hydrocarbon ratio parameter combinations for metamorphic rock reservoirs include C1 / C4 and C1 / nC5.

9. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to any one of claims 6 to 8, characterized in that... The hydrocarbon ratio parameter combinations for shale reservoirs include iC4 / nC4 and C4 / C3.

10. The method for establishing interpretation and evaluation charts for unconventional reservoirs based on hydrocarbon ratios according to any one of claims 6 to 9, characterized in that... The hydrocarbon ratio parameter combinations for low-resistivity reservoirs include C1 / C2 and (C4+C5) / C3.

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