阅读说明：本技术 一种低勘探新区断陷湖盆烃源岩sastf预测方法 (Method for predicting SASTF (Source rock of hydrocarbon) of fractured lake basin in low exploration new area ) 是由 李磊 龚广传 剧永涛 张威 刘豪 于 2021-01-12 设计创作，主要内容包括：一种低勘探新区断陷湖盆烃源岩SASTF预测方法,先在钻井已证实富烃洼陷,计算各烃源岩发育层系的洼陷总沉降量,求取最小值作为可发育深湖-半深湖环境总沉降量的下限；总结发育深湖-半深湖烃源岩地层的地震相,建立深湖-半深湖烃源岩地震相识别标准；然后在低勘探待证实洼陷,计算洼陷总沉降量,寻找潜在可发育深湖-半深湖的洼陷；在潜在可发育深湖-半深湖的洼陷,依据洼陷可容空间与沉积物供给关系寻找发育深湖-半深湖泥岩的洼陷；最后综合考虑湖盆类型,结合深湖-半深湖相烃源岩地震相识别标准,预测烃源岩空间展布；本发明能够准确预测优质烃源岩发育的富烃洼陷,降低油气勘探风险,提高钻井成功率,降低油气勘探成本。(A SASTF prediction method for source rocks of a fractured-subsided lake basin in a new low exploration area comprises the steps of firstly drilling wells to prove that hydrocarbon-rich depressions are formed, calculating the total depression settlement of each hydrocarbon source rock development layer system, and calculating the minimum value to serve as the lower limit of the total settlement of the developable deep lake-semi-deep lake environment; summarizing the seismic facies of the hydrocarbon source rock stratum of the developing deep lake and the semi-deep lake, and establishing a seismic facies identification standard of the hydrocarbon source rock of the deep lake and the semi-deep lake; then, in low exploration to-be-confirmed depressions, calculating the total depression amount of the depressions, and searching for the depressions of the potential developable deep lake-semi-deep lake; in the depression of the potential developable deep lake-semi-deep lake, finding the depression of the mudstone of the developable deep lake-semi-deep lake according to the relation between the depression accommodating space and the sediment supply; finally, comprehensively considering the types of the lakes and basins, and predicting the spatial distribution of the source rocks by combining the seismic facies identification standards of the source rocks in the deep lake-semi-deep lake facies; the method can accurately predict the hydrocarbon-rich depression developed by the high-quality hydrocarbon source rock, reduce the risk of oil-gas exploration, improve the success rate of well drilling and reduce the cost of oil-gas exploration.)

1. A SASTF prediction method for a hydrocarbon source rock of a fractured lake basin in a low exploration new area is characterized by comprising the following steps:

1) calculating the total subsidence S of each hydrocarbon source rock development layer depression by using the formulas (1) to (3) in the n drilled hydrocarbon-rich depressions_m(TotalSubsidence)：S_m1,S_m2,S_m3,……,S_mnAnd find the minimum value S₀＝min{S_m1,S_m2,S_m3……S_mnThe lower limit of the standard sedimentation quantity of the environment of the developable deep lake-semi-deep lake is taken as;

S_m＝S_T+S_Th (1)

wherein S is_m: total sedimentation, m; s_T: construction settling amount, m; s_Th: thermal settling amount, m; rho_m: mantle density of 3.33g/cm³；ρ_s: average density of deposit, 2.30g/cm³；ρ_wLake water density, 1.00g/cm³；H_cCompaction corrected deposit fill thickness, m; w_d: depth of ancient lake water, m; delta S_L: relative to the present ancient lake plane variation, m; beta: the tensile coefficient is 1.1-1.7, and the drawing die is dimensionless; alpha is alpha_v: coefficient of thermal expansion, 3.28X 10^-5C^-1；T_a: soft flow circle temperature, 1333 ℃; y is_L: initial rock ring thickness, 125 km;

2) summarizing and summarizing seismic facies characteristics of the hydrocarbon source rock stratum of the developing deep lake-semi-deep lake on n hydrocarbon-rich depressions verified by drilling wells, and establishing a recognition standard of the hydrocarbon source rock seismic facies F (Seismic facilities) of the deep lake-semi-deep lake;

3) calculating the total subsidence quantity S of k depressions to be verified in the low exploration new area by using the formulas (1) to (3): s₁，S₂，……,S_kAccording to S>S_m0Searching for depressions of potentially developable deep lakes-semi-deep lakes;

4) in the depressions of the potential developable deep lake-semi-deep lake, further searching depressions of mudstones of the developable deep lake-semi-deep lake, wherein A/S (Accommodation/segment Supply) is more than or equal to 1 according to the depression accommodating space and Sediment Supply relation A/S;

5) comprehensively considering Lake-Basin Types T (Lake-base Types), the deep Lake-half deep Lake mudstone which is filled with sunk and developed in a balanced mode is beneficial to the development of the hydrocarbon source rock, and the spatial distribution of the hydrocarbon source rock is predicted by combining the identification standard of the deep Lake-half deep Lake facies hydrocarbon source rock seismic facies F (Seismic facies).

Technical Field

The invention relates to the technical field of hydrocarbon source rock prediction, in particular to a SASTF prediction method for a hydrocarbon source rock of a fractured lake basin in a new low exploration area.

Background

Whether the high-quality hydrocarbon source rock is accurately predicted or not restricts the development of the oil-gas exploration industry in China, and the accurate recognition and prediction of the hydrocarbon-rich depression can reduce the exploration risk of the oil-gas reservoir, improve the drilling success rate and reduce the exploration cost of the oil-gas reservoir, so that the method has important significance.

The existing hydrocarbon source rock prediction and evaluation method based on geochemistry and drilling logging information establishes a hydrocarbon source rock TOC quantitative prediction model through actually measured TOC data of a mudstone sample and logging and seismic data to predict the hydrocarbon source rock, and has the following defects: the method has certain limitation in a low exploration new area without wells or with few wells, and cannot realize effective prediction of the hydrocarbon source rock.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a SASTF (source rock SASTF) prediction method for fractured lake basin in a low exploration new area, which can realize effective prediction on the source rock.

In order to achieve the purpose, the invention adopts the technical scheme that:

a SASTF prediction method for a hydrocarbon source rock of a fractured lake basin in a low exploration new area comprises the following steps:

1) calculating the total subsidence S of each hydrocarbon source rock development layer depression by using the formulas (1) to (3) in the n drilled hydrocarbon-rich depressions_m(Total Subsidence)：S_m1,S_m2,S_m3,……,S_mnAnd find the minimum value S_m0＝min{S_m1,S_m2,S_m3……S_mnThe lower limit of the standard sedimentation quantity of the environment of the developable deep lake-semi-deep lake is taken as;

S_m＝S_T+S_Th (1)

wherein S is_m: total sedimentation, m; s_T: construction settling amount, m; s_Th: thermal settling amount, m; rho_m: mantle density of 3.33g/cm³；ρ_s: average density of deposit, 2.30g/cm³；ρ_wLake water density, 1.00g/cm³；H_cCompaction corrected deposit fill thickness, m; w_d: depth of ancient lake water, m; delta S_L: relative to the present ancient lake plane variation, m; beta: the tensile coefficient is 1.1-1.7, and the drawing die is dimensionless; alpha is alpha_v: coefficient of thermal expansion, 3.28X 10^-5C^-1；T_a: soft flow circle temperature, 1333 ℃; y is_L: initial rock ring thickness, 125 km;

2) summarizing and summarizing seismic facies characteristics of the hydrocarbon source rock stratum of the developing deep lake-semi-deep lake on n hydrocarbon-rich depressions verified by drilling wells, and establishing a deep lake-semi-deep lake hydrocarbon source rock seismic facies F (Seismic facies) identification standard;

3) calculating the total subsidence quantity S of k depressions to be verified in the low exploration new area by using the formulas (1) to (3): s₁，S₂，……,S_kAccording to S>S_m0Searching for depressions of potentially developable deep lakes-semi-deep lakes;

4) in the depressions of the potential developable deep lake-semi-deep lake, further searching depressions of mudstones of the developable deep lake-semi-deep lake, wherein the A/S is more than or equal to 1, according to the depression accommodating space and sediment supply relation A/S (accumulation/SegmentSupply);

5) comprehensively considering Lake-Basin Types T (Lake-base Types), the deep Lake-half deep Lake mudstone which is filled with sunk and developed in a balanced mode is beneficial to the development of the hydrocarbon source rock, and the spatial distribution of the hydrocarbon source rock is predicted by combining the identification standard of the deep Lake-half deep Lake facies hydrocarbon source rock seismic facies F (Seismic facies).

The invention has the beneficial effects that:

the hydrocarbon source rock SASTF prediction technology is adopted, the problem that the hydrocarbon source rock cannot be predicted in a new low exploration area without or with few wells by using the existing hydrocarbon source rock prediction and evaluation method based on geochemistry and drilling logging information is solved, the risk of oil and gas exploration is reduced, and the success rate of the oil and gas exploration is really improved.

The method can accurately predict the hydrocarbon-rich depression of high-quality source rock development, can be applied to oil-gas exploration work in low exploration areas, can reduce the oil-gas exploration risk, can effectively improve the drilling success rate, reduces the oil-gas exploration cost, and has important application prospect and economic value.

Drawings

FIG. 1 is a flow chart of the present invention.

FIG. 2 is a well bore well adjacent to a low exploration A zone showing 6 hydrocarbon-rich depressions (A) of example 1 of the present invention_m1～A_m6) Total sedimentation histogram.

FIG. 3 is a typical seismic facies of source rock from 6 hydrocarbon-rich depressed deep-semi-deep lakes confirmed by drilling adjacent to the low exploration area A of example 1 of the present invention.

FIG. 4 shows the depressions in the area A of low exploration according to example 1 of the present invention (A)₁～A₈) Total sedimentation histogram.

FIG. 5 shows a low survey area A of example 1 of the invention₁Lake basin type, seismic facies typical seismic profiles.

FIG. 6 shows a low survey area A of example 1 of the invention₁Depression of a certain section of source rock predicts a plan view.

FIG. 7 is a well bore having demonstrated 5 hydrocarbon-rich depressions adjacent to the low exploration zone B of example 2 of the present invention (B)_m1～B_m5) Total sedimentation histogram.

FIG. 8 is a typical seismic facies of 5 hydrocarbon-rich depressed deep-semi-deep lake source rocks confirmed by drilling adjacent to the low exploration zone B of example 2 of the present invention.

FIG. 9 shows depressions in the low exploration zone B (B) in example 2 of the present invention₁～B₇) Total sedimentation histogram.

FIG. 10 shows a low survey zone B of example 2 of the invention₁Lake basin type, seismic facies typical seismic profiles.

FIG. 11 shows a low survey zone B of example 2 of the invention₁Depression of a certain section of source rock predicts a plan view.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

Example 1, referring to fig. 1, a new area of low exploration a, a method for predicting saptf of a hydrocarbon source rock of a fractured lake basin in a new area of low exploration, comprising the steps of:

1) in 6 hydrocarbon-rich pits which are proved to be drilled, the total sinking amount S of the pits of each hydrocarbon source rock development layer series is calculated by using the formulas (1) to (3)_m(TotalSubsidence)：S_m1,S_m2,S_m3,……,S_m6And find the minimum value S_m0＝min{S_m1,S_m2,S_m3……S_m6450 is taken as the lower limit of the standard sedimentation volume of the environment of the developable deep lake and the semi-deep lake;

S_m＝S_T+S_Th (1)

wherein S is_m: total sedimentation, m; s_T: construction settling amount, m; s_Th: thermal settling amount, m; rho_m: mantle density of 3.33g/cm³；ρ_s: average density of deposit, 2.30g/cm³；ρ_wLake water density, 1.00g/cm³；H_cCompaction corrected deposit fill thickness, m; w_d: depth of ancient water, m; delta S_L: relative to the present ancient lake plane variation, m; beta: the tensile coefficient is 1.1-1.7, and the drawing die is dimensionless; alpha is alpha_v: coefficient of thermal expansion, 3.28X 10^-5C^-1；T_a: soft flow circle temperature, 1333 ℃; y is_L: initial rock ring thickness, 125 km; the lower limit S of the total sinking amount of the developable deep lake-semi-deep lake depression_m0Determination of (D), as shown in FIG. 2, it can be seen from the graph that the total amount of sinking of developing deep-semi-deep lake depressions is belowLimit of S_m0＝450m；

2) Summarizing and summarizing the seismic facies characteristics of the hydrocarbon source rock stratum of the developing deep lake-semi-deep lake in 6 hydrocarbon-rich depressions confirmed by drilling wells, establishing a deep lake-semi-deep lake hydrocarbon source rock seismic facies F (Seismic facilities) identification standard, and as shown in FIG. 3, it can be seen that a typical deep lake-semi-deep lake hydrocarbon source rock seismic facies has one of 4 types of characteristics: medium-low amplitude, medium-low frequency wave-like-chaotic character; low amplitude, low frequency composite-blank reflection characteristics; low amplitude, medium and low frequency low continuous composite characteristics; the parallel sub-parallel reflection clip with medium and strong amplitude has no reflection characteristic;

3) calculating the total settlement S of 8 depressions to be proved in the low exploration new area by using the formulas (1) - (3)₁，S₂，……,S₈According to S>S_m0Looking for a depression potentially developable deep-semi-deep lake as 450m, as shown in fig. 4, it can be seen that the total amount of subsidence of a1, a5, a6 and A8 depressions is greater than S_m0(450m), each of these 4 depressions has the potential to develop deep-semi-deep lakes;

4) in the depression of the potential developable deep lake-semi-deep lake, according to the relation A/S (Accommodation/segment Supply) between depression accommodating space and Sediment Supply, the depression of the developmental deep lake-semi-deep lake mudstone with A/S being more than or equal to 1 is further searched, as shown in FIG. 5, A1 depression A/S being more than or equal to 1 can be seen in the drawing, and the depression develops the deep lake-semi-deep lake mudstone;

5) comprehensively considering Lake Basin Type T (Lake-base Type), the method for balancing and filling deep Lake-half deep Lake mudstone with crater development is beneficial to the development of hydrocarbon source rocks, and the spatial distribution of the hydrocarbon source rocks is predicted by combining the recognition standards of seismic facies F (Seismicfacies) of the deep Lake-half deep Lake facies hydrocarbon source rocks, as shown in figure 6, it can be seen that A1 crater upper Wenchang group develops the deep Lake-half deep Lake facies hydrocarbon source rocks, and the area is 42km²。

The beneficial effect of this embodiment does: a) the hydrocarbon source rock is predicted by using factors such as total subsidence S, depression A/S, lake basin type T, seismic facies F and the like of the depression to be confirmed in a low exploration new area based on the hydrocarbon source rock recognition standard of the hydrocarbon-rich depression confirmed in a well drilling, and the limitation that the hydrocarbon source rock cannot be predicted in the low exploration new area without wells or with few wells by the existing hydrocarbon source rock prediction and evaluation method based on geochemistry and drilling logging information is overcome.

b) According to the method, the hydrocarbon source rock is predicted based on the seismic data of the low exploration new area by integrating the factors such as total settlement S, A/S, the lake basin type T and the seismic facies F, and the multi-solution of the geophysical inversion problem solution of the hydrocarbon source rock is reduced by seismic inversion prediction.

c) According to the hydrocarbon source rock space prediction result, the target evaluation of the low exploration area A is effectively promoted, and the exploration risk is reduced.

Example 2, referring to fig. 1, a new region of low exploration B, a method for predicting saptf of a hydrocarbon source rock of a fractured lake basin in a new region of low exploration, comprising the steps of:

1) in 5 confirmed hydrocarbon-rich pits drilled by well, calculating total sinking amount S of each hydrocarbon source rock development layer series by using formulas (1) to (3)_m(TotalSubsidence)：S_m1,S_m2,S_m3,……,S_m5And find the minimum value S_m0＝min{S_m1,S_m2,S_m3……S_m5480 is used as the lower limit of the standard sedimentation volume of the environment of the developable deep lake and the semi-deep lake;

S_m＝S_T+S_Th (1)

wherein S is_m: total sedimentation, m; s_T: construction settling amount, m; s_Th: thermal settling amount, m; rho_m: mantle density of 3.33g/cm³；ρ_s: average density of deposit, 2.30g/cm³；ρ_wLake water density, 1.00g/cm³；H_cCompaction corrected deposit fill thickness, m; w_d: depth of ancient water, m; delta S_L: relative to the present ancient lake plane variation, m; beta: tensile modulus, 1.1-1.7, dimensionless; alpha is alpha_v: coefficient of thermal expansion, 3.28X 10^-5C^-1；T_a: soft flow circle temperature, 1333 ℃; y is_L: initial rock ring thickness, 125 km. This example B can develop the lower limit S of the total sinking amount of deep lake-semi-deep lake depression_m0As shown in FIG. 7, the lower limit S of the total sinking amount of the developing deep lake-semi-deep lake pits can be seen_m0＝480m；

2) Summarizing and summarizing the seismic facies characteristics of the hydrocarbon source rock stratum of the developing deep lake-semi-deep lake in 5 hydrocarbon-rich depressions confirmed by drilling wells, establishing a deep lake-semi-deep lake hydrocarbon source rock seismic facies F (Seismic facilities) identification standard, and as shown in FIG. 8, it can be seen that a typical deep lake-semi-deep lake hydrocarbon source rock seismic facies has one of 4 types of characteristics: medium-low amplitude, medium-low frequency wave-like-chaotic character; low amplitude, low frequency composite-blank reflection characteristics; low amplitude, medium and low frequency low continuous composite characteristics; the parallel sub-parallel reflection clip with medium and strong amplitude has no reflection characteristic;

3) calculating the total settlement S of 7 depressions to be verified in the low exploration area by using the formulas (1) - (3)₁，S₂，……,S₇According to S>S_m0Looking for potential deep-semi-deep-lake depressions as 480m, as shown in fig. 9, it can be seen that the total amount of depression from B1 depressions to B6 depressions is greater than S_m0(480m), each of the 6 depressions has the potential to develop deep-semi-deep lakes;

4) in the depression of the potential developable deep lake-semi-deep lake, according to the relation A/S (Accommodation/segment Supply) between depression accommodating space and Sediment Supply, the depression of the developmental deep lake-semi-deep lake mudstone with A/S being more than or equal to 1 is further searched, as shown in FIG. 10, B1 depression A/S being more than or equal to 1 can be seen in the drawing, and the depression develops the deep lake-semi-deep lake mudstone;

5) comprehensively considering Lake Basin Type T (Lake-base Type), the method for predicting the spatial distribution of the hydrocarbon source rocks by balancing and filling deep Lake-semi-deep Lake mudstones with crater development is favorable for the development of the hydrocarbon source rocks, and the method is combined with the identification standard of deep Lake-semi-deep Lake facies hydrocarbon source rock seismic facies F (Seismic facies) to predict the spatial distribution of the hydrocarbon source rocks, as shown in FIG. 11, B1 craters and B2 crater engin groups develop the deep Lake-semi-deep Lake facies hydrocarbon source rocks, and the areas of the source rocks are 25km respectively²And 37km²。

The beneficial effect of this embodiment does: a) the hydrocarbon source rock is predicted by using factors such as total subsidence S, depression A/S, lake basin type T, seismic facies F and the like of the depression to be confirmed in a low exploration new area based on the hydrocarbon source rock recognition standard of the hydrocarbon-rich depression confirmed in a well drilling, and the limitation that the hydrocarbon source rock cannot be predicted in the low exploration new area without wells or with few wells by the existing hydrocarbon source rock prediction and evaluation method based on geochemistry and drilling logging information is overcome.

b) According to the method, the hydrocarbon source rock is predicted by integrating factors such as total settlement S, depression A/S, lake basin type T and seismic facies F based on seismic data of a low exploration new area, and the multi-solution of a geophysical inversion problem solution of the hydrocarbon source rock is reduced through seismic inversion prediction.

c) Based on the hydrocarbon source rock space prediction result of the hydrocarbon source rock SASTF prediction technology of the low exploration new area fractured lake basin, the target evaluation of the low exploration B area is effectively promoted, and the exploration risk is reduced.