An oil source correlation method

Abstract

The present invention relates to an oil-source correlation method, belonging to the technical field of oil and gas exploration and development. The oil-source correlation method includes: obtaining the current biomarker parameters, current maturity of potential source rocks, and the biomarker parameters of crude oil; obtaining the biomarker parameters of the current residual oil in the potential source rocks according to the current maturity and the residual oil biomarker parameter model; obtaining the restored biomarker parameters of the current residual oil in the potential source rocks according to the current maturity and the restored biomarker parameter model; and then obtaining the biomarker parameters of the current expelled oil in the potential source rocks; obtaining the change in biomarker parameters according to the biomarker parameters of the current expelled oil and the biomarker parameters of the crude oil; correcting the current biomarker parameters of the potential source rocks according to the change in biomarker parameters, and then conducting oil-source correlation. The present invention takes into account the changes in biomarker parameters during the subsidence process of source rocks and the changes in biomarker parameters during the hydrocarbon expulsion process, obtains accurate biomarker parameters of source rocks, and improves the accuracy of oil-source correlation with crude oil.

Description

Technical Field

[0001] The present invention relates to an oil source correlation method, belonging to the technical field of oil and gas exploration and development. Background Art

[0002] Oil source correlation is an important link in the process of oil and gas exploration and development for finding reservoirs from sources or finding sources from reservoirs, and is an important technical means for determining the source of oil and gas, analyzing the migration direction of oil and gas, and predicting the distribution of oil and gas reservoirs.

[0003] The existing oil source correlation methods are mainly realized by comparing the chromatograms, chromatogram-mass spectrometry fingerprint patterns and biomarker compound parameters of soluble organic matter in source rocks and crude oil. First, chromatographic and chromatogram-mass spectrometric analyses are carried out on the soluble organic matter in source rocks and the saturated hydrocarbons and aromatics in crude oil, and the comparison of the spectral patterns between the source rocks and the crude oil is carried out. Samples with similar spectral patterns are considered to have a genetic relationship. Secondly, representative biomarker compounds are selected for parameter calculation, and source rocks and crude oil with similar biomarker compound parameters are treated as homologous (that is, the crude oil is generated by hydrocarbon expulsion from the source rock). Finally, comprehensive analysis is carried out to complete the final oil source correlation analysis.

[0004] The above oil source correlation methods are already very mature. However, due to the usually large differences in the burial depths of oil and gas reservoirs and source rocks in geological bodies, and the source rocks will continue to be deeply buried with the subsidence of the strata after hydrocarbon expulsion, the thermal evolution degree of the source rocks is usually higher than that of the crude oil in the oil and gas reservoirs, resulting in the maturity of the source rocks being higher than the maturity of the generated crude oil. In different thermal evolution stages of maturity, there are large differences in the contents of biomarker compounds in the soluble organic matter of the source rocks, which in turn leads to corresponding changes in the biomarker compound parameters (abbreviated as biomarker parameters). At the same time, during the process of hydrocarbon expulsion from the source rock to generate crude oil, there will also be a phenomenon that there are differences in the biomarker compounds between the crude oil in the oil reservoir and the originally generated hydrocarbons, ultimately resulting in large errors in the oil source correlation results. Summary of the Invention

[0005] The purpose of the present application is to provide an oil source correlation method to solve the problem of inaccurate existing oil source correlation results.

[0006] To achieve the above purpose, the present application proposes a technical solution for an oil source correlation method, including the following steps:

[0007] 1) Obtain the current biomarker parameters, current maturity of potential source rocks, and the biomarker parameters of crude oil;

[0008] 2) Obtain the biomarker parameters of the current residual oil in the potential source rock based on the current maturity and the residual oil biomarker parameter model; obtain the restored biomarker parameters of the current residual oil in the potential source rock based on the current maturity and the restored biomarker parameter model; the residual oil biomarker parameter model is the first correspondence between maturity and biomarker parameters; the restored biomarker parameter model is the second correspondence between maturity and the restored amount of biomarker parameters;

[0009] 3) Obtain the biomarker parameters of the current expelled oil in the potential source rock based on the biomarker parameters of the current residual oil and the restored biomarker parameters of the current residual oil;

[0010] 4) Obtain the change in biomarker parameters based on the biomarker parameters of the current expelled oil and the biomarker parameters of the crude oil;

[0011] 5) Correct the current biomarker parameters of the potential source rock according to the change in biomarker parameters to obtain the corrected biomarker parameters of the potential source rock; conduct oil-source correlation using the corrected biomarker parameters of the potential source rock and the biomarker parameters of the crude oil.

[0012] The beneficial effects of the technical solution of the oil-source correlation method of the present invention are as follows: The present invention obtains the biomarker parameters and the restored biomarker parameters of the current residual oil in the potential source rock through the current maturity of the potential source rock, the established residual oil biomarker parameter model and the restored biomarker parameter model, and then obtains the biomarker parameters of the current expelled oil, reducing the difference in biomarker parameters during the hydrocarbon expulsion process; and then, the change in biomarker parameters is obtained by using the biomarker parameters of the crude oil and the biomarker parameters of the current expelled oil. This change represents the change in biomarker parameters of the potential source rock during the subsidence process based on the assumption that the crude oil belongs to the potential source rock. Therefore, the current biomarker parameters of the potential source rock are corrected according to this change to obtain the accurate biomarker parameters of the potential source rock when generating the crude oil, and then the oil-source correlation is completed. If the difference in oil-source correlation is small after correction, it is determined that the crude oil and the potential source rock are of the same origin. If, under this assumption, the difference in the corrected biomarker parameters is still large after oil-source correlation, then the crude oil and the potential source rock are not of the same origin. The present invention takes into account the change in biomarker parameters during the subsidence process of the source rock and the change in biomarker parameters during the hydrocarbon expulsion process, obtains the accurate biomarker parameters of the source rock, and improves the accuracy of oil-source correlation with the crude oil.

[0013] Further, the maturity is the vitrinite reflectance.

[0014] Furthermore, in order to accurately obtain the residual oil biomarker parameter model and the restored biomarker parameter model, the residual oil biomarker parameter model and the restored biomarker parameter model are obtained based on a hydrocarbon generation and expulsion simulation experiment on the source rock: during the experiment, the residual oil and expelled oil of the source rock at different stages are collected to obtain the biomarker parameters of the residual oil, the biomarker parameters of the expelled oil and the maturity of the different stages. The first correspondence between the maturity and the biomarker parameters is obtained by fitting the biomarker parameters and maturity of the residual oil at different stages, and then the residual oil biomarker parameter model is obtained; the second correspondence between the maturity and the biomarker parameter recovery amount is obtained by fitting the difference between the biomarker parameters of the residual oil and the expelled oil at different stages, and the maturity, and the restored biomarker parameter model is obtained.

[0015] Furthermore, the residual oil biomarker parameter model is:

[0016] Y 残 =a1R n +b1R n-1 +c1R n-2 +······+k1;

[0017] Where: Y 残 is the bio-standard parameter of residual oil; R is the maturity of residual oil; a1, b1, c1... are the polynomial coefficients of the bio-standard parameter model of residual oil; k1 is the constant of the bio-standard parameter model of residual oil; n is the degree of polynomial.

[0018] Furthermore, the biomarker parameter model is restored:

[0019] Z 恢复 =a2R n +b2R n-1 +c2R n-2 +······+k2;

[0020] Where: Z 恢复 is the bio-standard parameter recovery amount; R is the maturity of the residual oil; a2, b2, c2... are the polynomial coefficients of the bio-standard parameter recovery model; k2 is the constant of the bio-standard parameter recovery model; n is the polynomial degree.

[0021] Furthermore, in step 1), the bio-standard parameters of the crude oil are obtained according to actual measurements or according to a bio-standard parameter model of the crude oil maturity and residual oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the oil source comparison method of the present invention;

[0023] Figure 2 It is a flow chart for establishing the residual oil biomarker parameter model and the recovery biomarker parameter model of the present invention. DETAILED DESCRIPTION

[0024] Embodiment of the oil-source correlation method:

[0025] The main concept of the oil-source correlation method proposed by the present invention lies in that after the hydrocarbon source rock expels hydrocarbons and continues to subside, the thermal evolution degree of the hydrocarbon source rock is different from that of the crude oil, resulting in different maturities of the hydrocarbon source rock and the crude oil. Furthermore, there are significant differences in the biomarker parameters of the homologous hydrocarbon source rock and crude oil, and the problem of inaccurate oil-source correlation. After assuming that the crude oil and the potential hydrocarbon source rock are homologous, the present invention obtains the changes in the biomarker parameters of the hydrocarbon source rock during the subsidence process through the evolution of the biomarker parameters of the crude oil and the currently expelled oil. Then, based on the current biomarker parameters of the potential hydrocarbon source rock and the changes in the biomarker parameters during the subsidence process, the biomarker parameters of the potential hydrocarbon source rock corresponding to the crude oil stage are obtained, making the comparison result with the homologous crude oil more accurate. Of course, if under this homologous assumption, the difference between the biomarker parameters of the hydrocarbon source rock corresponding to the crude oil and the biomarker parameters of the crude oil is still very large, then it is determined as a non-homologous situation.

[0026] Specifically, the oil-source correlation method is as Figure 1 shown, and includes the following steps:

[0027] 1) Obtain the current biomarker parameters, current maturity of the potential hydrocarbon source rock, and the biomarker parameters of the crude oil.

[0028] In this embodiment, the current maturity R of the potential hydrocarbon source rock is the vitrinite reflectance Ro of the current residual oil of the potential hydrocarbon source rock measured according to the industry standard SY / T 5124-2012 Determination Method of Vitrinite Reflectance in Sedimentary Rocks.

[0029] The potential hydrocarbon source rock is the hydrocarbon source rock in the target area, and the crude oil here is the crude oil around the target area. The method of the present invention is realized based on the assumption that the crude oil is expelled from the potential hydrocarbon source rock. The current biomarker parameters of the potential hydrocarbon source rock and the biomarker parameters of the crude oil are the biomarker fingerprint data of the soluble organic matter of the potential hydrocarbon source rock and the saturated hydrocarbons and aromatics of the crude oil obtained according to the current industry standards GB / T 18340.5-2010 and GB / T 18606-2001.

[0030] 2) Obtain the biomarker parameters of the current residual oil in the potential hydrocarbon source rock according to the current maturity in step 1) and the pre-established residual oil biomarker parameter model; obtain the restored biomarker parameters of the current residual oil in the potential hydrocarbon source rock according to the current maturity and the pre-established restored biomarker parameter model.

[0031] The establishment process of the residual oil biomarker parameter model and the restored biomarker parameter model is as Figure 2 shown:

[0032] a. Collect potential source rock samples from different wells in a certain area. The potential source rock is the possible origin of crude oil. According to industry standards, obtain the biomarker parameters of the soluble organic matter in the source rock. The relevant parameters are shown in Table 1:

[0033] Table 1 Statistical Table of Biomarker Parameters

[0034]

[0035] As can be seen from Table 1, the biomarker parameters include Pr / Ph, C 30 * / C 30 H, C 19 TT / C 23 TT, C 20 TT / C 23 TT, Ts / (Ts + Tm), C 29 -ββ / (ββ + αα), C 29 -20S / (20S + 20R), rearranged sterane / regular sterane. The values of the biomarker parameters corresponding to different potential source rock samples are different. Due to the different types of potential source rock samples, according to the above biomarker parameters, perform finite-space hydrocarbon generation and expulsion simulation experiments on each potential source rock sample respectively, and collect the residual oil and expelled oil at different thermal simulation stages. In this embodiment, take the experimental process of a certain potential source rock sample as an example to describe the establishment process of the residual oil biomarker parameter model and the restored biomarker parameter model.

[0036] b. Perform chromatography and chromatography-mass spectrometry analysis on the residual oil and expelled oil at different thermal simulation stages, calculate the biomarker parameters of the residual oil and historical expelled oil, and simultaneously measure the vitrinite reflectance Ro of the residual oil at each thermal simulation stage.

[0037] c. Establish a correlation chart of the residual oil biomarker parameters and the vitrinite reflectance based on the residual oil biomarker parameters and the vitrinite reflectance obtained in step b, and perform data fitting to establish a polynomial numerical model of the relationship between the residual oil biomarker parameters and the vitrinite reflectance Ro, and obtain the following residual oil biomarker parameter model:

[0038] Y 残 =a1R o n +b1R o n-1 +c1R o n-2 +······+k1;

[0039] Where: Y 残They are the biomarker parameters of residual oil; Ro is the vitrinite reflectance of residual oil, representing the maturity index, %; a1, b1, c1... are the polynomial coefficients of the biomarker parameter model of residual oil; k1 is the constant of the biomarker parameter model of residual oil; n is the polynomial degree.

[0040] The established biomarker parameter model of residual oil is shown in Table 2:

[0041] Table 2 Mathematical models of different biomarker parameters

[0042] Serial number Biogenic marker parameter Mathematical model Fitting coefficient 1 Pr / Ph <![CDATA[Y = 0.6158x 2 - 0.9408x + 0.4793]]> <![CDATA[R 2 = 0.9914]]> 2 <![CDATA[C 30 * / C 30 H]]> <![CDATA[Y = 0.1193x 2 - 0.2197x + 0.1024]]> <![CDATA[R 2 = 0.9783]]> 3 <![CDATA[C 19 TT / C 23 TT]]> <![CDATA[Y = 0.0634x 2 -0.1188x + 0.0805]]> <![CDATA[R 2 = 0.9401]]> 4 <![CDATA[C 20 TT / C 23 TT]]> <![CDATA[Y = -0.7891x 3 + 2.5209x 2 - 2.4538x + 0.9391]]> <![CDATA[R 2 = 0.995]]> 5 Ts / (Ts+Tm) <![CDATA[Y = 0.6034x 2 - 1.2392x + 0.7861]]> <![CDATA[R 2 = 0.9203]]> 6 <![CDATA[C 29 -ββ / (ββ + αα)]]> <![CDATA[Y = 0.0832x 2 -0.1456x + 0.2431]]> <![CDATA[R 2 = 0.951]]> 7 <![CDATA[C 29 -20S / (20S + 20R)]]> Y = 0.0999x + 0.0975 <![CDATA[R 2 = 0.9363]]> 8 Rearranged sterane / Regular sterane <![CDATA[Y = 0.0294x 2 + 0.0121x + 0.0979]]> <![CDATA[R 2 = 0.9513]]>

[0043] Similarly, the difference between the biomarker parameters of the residual oil and expelled oil obtained in step b is used to obtain the recovery amount of biomarker parameters for the residual oil to be restored to the expelled oil. A correlation chart of the recovery amount of biomarker parameters and the vitrinite reflectance of residual oil is established, and data fitting is performed to obtain the recovery biomarker parameter model:

[0044] Z 恢复 = a2R o n + b2R o n-1 + c2R o n-2 + ······ + k2;

[0045] Among them: Z 恢复 is the recovery amount of biomarker parameters; Ro is the vitrinite reflectance of residual oil, %; a2, b2, c2... are the polynomial coefficients of the recovery biomarker parameter model; k2 is the constant of the recovery biomarker parameter model; n is the polynomial degree.

[0046] In this step, the recovery amount of biomarker parameters = the biomarker parameters of expelled oil - the biomarker parameters of residual oil, or the recovery amount of biomarker parameters = the biomarker parameters of residual oil - the biomarker parameters of expelled oil. For different formulas, the subsequent calculation formulas for the biomarker parameters of the current expelled oil are different.

[0047] The finally obtained recovery mathematical models of different biomarker parameters are shown in Table 3:

[0048] Table 3 Recovery biomarker parameter model

[0049] Serial number Biogenic marker parameter Mathematical model Fitting coefficient 1 Pr / Ph <![CDATA[Z = 0.5483x 2 - 1.5758x + 0.3511]]> <![CDATA[R 2 = 0.9885]]> 2 <![CDATA[C 30 * / C 30 H]]> <![CDATA[Z = 0.1709x 3 - 0.5359x 2 + 0.5276x - 0.1919]]> <![CDATA[R 2 = 0.9123]]> 3 <![CDATA[C 19 TT / C 23 TT]]> <![CDATA[Z = -0.2868x 3 + 1.272x 2 - 1.7721x + 0.6506]]> <![CDATA[R 2 = 0.8531]]> 4 <![CDATA[C 20 TT / C 23 TT]]> <![CDATA[Z = -0.1469x 3 + 0.6389x 2 - 0.8703x + 0.311]]> <![CDATA[R 2 = 0.9517]]> 5 Ts / (Ts+Tm) <![CDATA[Z = 0.4243x 3 -1.3373x 2 +1.3209x - 0.4582]]> <![CDATA[R 2 = 0.9901]]> 6 <![CDATA[C 29 -ββ / (ββ+αα)]]> <![CDATA[Z = -0.0099x 2 + 0.045x - 0.1248]]> <![CDATA[R 2 = 0.9838]]> 7 <![CDATA[C 29 -20S / (20S + 20R)]]> <![CDATA[Z = 0.0475x 2 - 0.1104x - 0.0649]]> <![CDATA[R 2 = 0.9246]]> 8 Rearranged sterane / Regular sterane <![CDATA[Z = -0.1985x 3 + 0.6218x 2 - 0.5117x + 0.004]]> <![CDATA[R 2 = 0.9655]]>

[0050] In Table 2 and Table 3 above, x in the expression represents the vitrinite reflectance Ro. After obtaining the above-mentioned biomarker parameter model of residual oil and recovery biomarker parameter model, the current residual oil vitrinite reflectance of the potential hydrocarbon source rock is substituted into the biomarker parameter model of residual oil to obtain the biomarker parameters of the current residual oil, and the current residual oil vitrinite reflectance of the potential hydrocarbon source rock is substituted into the recovery biomarker parameter model to obtain the recovery biomarker parameters of the current residual oil.

[0051] The residual oil biomarker parameter model represents the first corresponding relationship between vitrinite reflectance and biomarker parameters, and the restored biomarker parameter model represents the second corresponding relationship between vitrinite reflectance and the restored amount of biomarker parameters. It is not only applicable to residual oil, but can be applied to the calculation of biomarker parameters of different samples at different vitrinite reflectances.

[0052] For different types of source rocks, the residual oil biomarker parameter model and the restored biomarker parameter model are not the same. To ensure the accuracy of the model, the present invention conducts hydrocarbon generation and expulsion simulation experiments on various types of source rocks to obtain the residual oil biomarker parameter model and the restored biomarker parameter model corresponding to various types of source rocks, and substitutes the current maturity of the potential source rock in step 1) into each model of the same type as the potential source rock type to obtain the corresponding biomarker parameters of the current residual oil and the restored biomarker parameters of the current residual oil.

[0053] 3) Obtain the biomarker parameters of the current expelled oil based on the biomarker parameters of the current residual oil and the restored biomarker parameters of the current residual oil in step 2).

[0054] If, when establishing the restored biomarker parameter model, the restored amount of biomarker parameters = the biomarker parameters of the expelled oil - the biomarker parameters of the residual oil, then the biomarker parameters of the current expelled oil = the biomarker parameters of the current residual oil + the restored biomarker parameters of the current residual oil; if, when establishing the restored biomarker parameter model, the restored amount of biomarker parameters = the biomarker parameters of the residual oil - the biomarker parameters of the expelled oil, then the biomarker parameters of the current expelled oil = the biomarker parameters of the current residual oil - the restored biomarker parameters of the current residual oil.

[0055] 4) Obtain the change in biomarker parameters based on the biomarker parameters of the current expelled oil in step 3) and the biomarker parameters of the crude oil in step 1).

[0056] Since it is assumed that the crude oil is expelled from the potential source rock, the change in biomarker parameters represents the change in biomarker parameters of the potential source rock during the crude oil generation stage and the current stage. The change in biomarker parameters = the biomarker parameters of the current residual oil - the biomarker parameters of the crude oil.

[0057] 5) Correct the current biomarker parameters of the potential source rock in step 1) based on the change in biomarker parameters to obtain the corrected biomarker parameters of the potential source rock.

[0058] The corrected biomarker parameters of the potential source rock are the biomarker parameters of the potential source rock during the crude oil generation stage. The corrected biomarker parameters of the potential source rock = the measured biomarker parameters of the current source rock - the change in biomarker parameters.

[0059] 6) Use the biomarker parameters of the corrected potential hydrocarbon source rock and the biomarker parameters of the crude oil for oil-source correlation. If the biomarker parameters differ little, it indicates that the crude oil is generated from the hydrocarbon expulsion of the potential hydrocarbon source rock. If the biomarker parameters differ greatly, it indicates that the crude oil is not generated from the hydrocarbon expulsion of the potential hydrocarbon source rock.

[0060] In the above embodiments, the biomarker parameters of the crude oil in step 1) are calculated according to the methods of the prior art. As other embodiments, the biomarker parameters of the crude oil can also be obtained through the maturity of the crude oil and the biomarker parameter model of the residual oil. The present invention does not limit this.

[0061] In the above embodiments, the vitrinite reflectance is used as the maturity index for the establishment of each model and the corresponding calculations. As other embodiments, the thermal alteration index or the bioclast reflectance can also be used as the maturity index. The present invention does not limit this.

[0062] The present invention corrects the thermal evolution of the biomarker parameters of the potential hydrocarbon source rock and restores the hydrocarbon expulsion process to obtain the biomarker parameters of the potential hydrocarbon source rock when generating the crude oil, thereby reducing the error of oil-source correlation. The present invention mainly eliminates the error of oil-source correlation between the crude oil and the potential hydrocarbon source rock that belong to the same source. However, according to experiments, even under the assumptions of the present invention, the difference between the biomarker parameters of the corrected potential hydrocarbon source rock and the biomarker parameters of the crude oil that do not belong to the same source is still very large. Therefore, this assumption holds and can be used as the basis for oil-source correlation.

Claims

1. An oil source comparison method, characterized in that: The following steps are involved: 1) Obtain the current biogenic parameters and maturity of potential source rocks and the biogenic parameters of crude oil; 2) Obtaining the bio-index parameters of the current residual oil in the potential source rock according to the current maturity and the residual oil bio-index parameter model; obtaining the restored bio-index parameters of the current residual oil in the potential source rock according to the current maturity and the restored bio-index parameter model; the residual oil bio-index parameter model is a first corresponding relationship between maturity and the bio-index parameter; the restored bio-index parameter model is a second corresponding relationship between maturity and the restored amount of the bio-index parameter; the residual oil bio-index parameter model and the restored bio-index parameter model are obtained by conducting a hydrocarbon generation and expulsion simulation experiment on the source rock: during the experiment, the residual oil and expelled oil of the source rock at different stages are collected to obtain the bio-index parameters of the residual oil, the bio-index parameters of the expelled oil and the maturity at different stages, and the first corresponding relationship between maturity and the bio-index parameter is obtained according to the bio-index parameters and maturity of the residual oil at different stages, thereby obtaining the residual oil bio-index parameter model; the second corresponding relationship between maturity and the restored amount of the bio-index parameter is obtained according to the difference between the bio-index parameters of the residual oil and the bio-index parameters of the expelled oil at different stages and the maturity, thereby obtaining the restored bio-index parameter model; 3) Obtaining bio-index parameters of the currently discharged oil in the potential source rock based on the bio-index parameters of the current residual oil and the bio-index parameters of the restored current residual oil; 4) Obtaining a bio-standard parameter change amount based on the bio-standard parameters of the currently discharged oil and the bio-standard parameters of the crude oil; 5) Correcting the current bio-index parameters of the potential source rock according to the variation of the bio-index parameters to obtain the corrected bio-index parameters of the potential source rock; and performing oil source comparison using the corrected bio-index parameters of the potential source rock and the bio-index parameters of crude oil.

2. The oil source comparison method according to claim 1, characterized in that: The maturity is vitrinite reflectance.

3. The oil source comparison method according to claim 1, characterized in that: The residual oil biomarker parameter model is: Y 残 =a1R n +b1R n-1 +c1R n-2 +······+k1; Where: Y 残 is the bio-standard parameter of residual oil; R is the maturity of residual oil; a1, b1, c1... are the polynomial coefficients of the bio-standard parameter model of residual oil; k1 is the constant of the bio-standard parameter model of residual oil; n is the degree of polynomial.

4. The oil source comparison method according to claim 1, characterized in that: The recovery parameter model: WITH 恢复 =a2R n +b2R n-1 +c2R n-2 +······+k2; Where: Z 恢复 is the bio-standard parameter recovery amount; R is the maturity of the residual oil; a2, b2, c2... are the polynomial coefficients of the bio-standard parameter recovery model; k2 is the constant of the bio-standard parameter recovery model; n is the polynomial degree.

5. The oil source comparison method according to claim 1, characterized in that: In step 1), the bio-standard parameters of the crude oil are obtained through actual measurement or through a bio-standard parameter model based on the maturity of the crude oil and the residual oil.

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