阅读说明：本技术 一种地层中烃源岩纵向非均质特征的定量表征方法 (Quantitative characterization method for longitudinal heterogeneous characteristics of hydrocarbon source rock in stratum ) 是由 王保华 陆建林 李�浩 宋振响 左宗鑫 王苗 刘娅昭 于 2018-06-05 设计创作，主要内容包括：本发明涉及一种地层中烃源岩纵向非均质特征的定量表征方法,其特征在于,包括以下步骤：确定输入参数数据；确定目标地层中烃源岩的纵向单元数目和纵向单元属性；确定目标地层中烃源岩的等效分布指数和分散系数；根据烃源岩的等效分布指数,确定烃源岩在目标地层纵向的分布位置,根据烃源岩的分散系数,确定烃源岩在目标地层纵向的离散程度。本发明能够定量描述不同品质烃源岩在地层中的纵向分布特征,以便于简易、直观、准确地开展地层中烃源岩评价。(the invention relates to a quantitative characterization method for longitudinal heterogeneous characteristics of a hydrocarbon source rock in a stratum, which is characterized by comprising the following steps of: determining input parameter data; determining the number of longitudinal units and the longitudinal unit attribute of the hydrocarbon source rock in the target stratum; determining the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in the target stratum; and determining the longitudinal distribution position of the source rock in the target stratum according to the equivalent distribution index of the source rock, and determining the longitudinal dispersion degree of the source rock in the target stratum according to the dispersion coefficient of the source rock. The method can quantitatively describe the longitudinal distribution characteristics of the source rocks with different qualities in the stratum so as to conveniently, simply, intuitively and accurately evaluate the source rocks in the stratum.)

1. a quantitative characterization method for longitudinal heterogeneous characteristics of a hydrocarbon source rock in a stratum is characterized by comprising the following steps:

Determining input parameter data;

Determining the number of longitudinal units and the longitudinal unit attribute of the hydrocarbon source rock in the target stratum;

Determining the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in the target stratum;

And determining the longitudinal distribution position of the source rock in the target stratum according to the equivalent distribution index of the source rock, and determining the longitudinal dispersion degree of the source rock in the target stratum according to the dispersion coefficient of the source rock.

2. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a subterranean formation of claim 1, wherein; determining the plane distribution diagram of the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in all target strata in the whole target area.

3. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a subterranean formation of claim 2, wherein; determining the main direction of a sediment source according to sedimentary facies data, and determining the plane distribution diagram of the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in all target strata of the whole target area by adopting a kriging interpolation algorithm, wherein the main direction of the kriging is the main direction of the sediment source.

4. the method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a formation according to any one of claims 1 to 3, wherein; the input parameter data includes lithology, porosity, density and organic carbon data volumes for different depths of the target formation and the source rock.

5. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a subterranean formation of claim 4, wherein; performing seismic geological inversion by using seismic data of a target stratum to obtain lithology, density, porosity and organic carbon data volumes of different depths of the target stratum and the hydrocarbon source rock;

Or the lithology, density, porosity and organic carbon data volumes of different depths of the target stratum and the hydrocarbon source rock are obtained in a spatial interpolation mode by utilizing the well drilling, earthquake and structural horizon data of the target stratum;

or determining lithology of different depths of the target stratum and the hydrocarbon source rock by using logging data in the drilling data, and determining density, porosity and organic carbon data volumes of different depths of the target stratum by using the logging data in the drilling data.

6. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a formation according to any one of claims 1 to 3, wherein; and determining the minimum value of the longitudinal step length of the target stratum according to the sampling rate of the input parameter data, and performing unit division on the longitudinal position of the target stratum.

7. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a subterranean formation of claim 6, wherein; determining mudstone units with organic carbon larger than the lower limit value of the organic carbon of the source rock in the longitudinal units of the target stratum as the source rock units, and determining the number of the longitudinal units of the source rock; the lower limit of the organic carbon of the source rock is 5%.

8. the method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a formation according to any one of claims 1 to 3, wherein; determining longitudinal cell property values of the source rock in the target formation includes depth, density, porosity, and organic carbon data of the source rock longitudinal cells.

9. The method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a formation according to any one of claims 1 to 3, wherein; firstly, determining the weighting parameter of the ith unit in the source rock, then determining the average value of the weighting parameter of the source rock, and then determining the equivalent buried depth and the equivalent distribution index of the source rock in the target stratum;

The formula for determining the weighting parameter of the ith unit in the source rock is as follows:

K_i＝C_i·ρ_i(1-Φ_i) (3)

in the formula, K_iAs a weighting parameter for the i-th cell in the source rock, C_iIs the average organic carbon content of unit i in the source rock, p_iIs the average density, phi, of units i in the source rock_iIs the average porosity of unit i in the source rock.

The formula for determining the average value of the weighting parameters of the source rock is as follows:

in the formula, K is the weighted parameter average value of the hydrocarbon source rock.

The formula according to which the equivalent burial depth of the source rock in the target formation is determined is as follows:

In the formula, H_iThe bottom buried depth of the unit i in the hydrocarbon source rock is shown, and H is the equivalent buried depth of the hydrocarbon source rock in the target stratum.

The formula according to which the equivalent distribution index of the source rock in the target formation is determined is as follows:

10. the method for quantitatively characterizing the longitudinal heterogeneity characteristics of a source rock in a subterranean formation of claim 9, wherein; determining the dispersion distance of the hydrocarbon source rock in the target stratum, and then determining the dispersion coefficient of the hydrocarbon source rock in the target stratum;

The formula according to which the dispersion distance of the source rock in the target formation is determined is:

Wherein R is the dispersion distance of the hydrocarbon source rock in the target stratum.

the formula according to which the dispersion coefficient of the source rock in the target formation is determined is:

R_max＝2(H-H_t)(H_b-H)/L (9)

R_min＝0 (10)

In the formula, R_maxIs the maximum value of the dispersion distance, R, of the hydrocarbon source rock in the target stratum_minis the minimum value of the dispersion distance of the hydrocarbon source rock in the target stratum, L is the thickness of the target stratum, H_bIs the bottom buried depth of the target formation, H_tthe top buried depth of the target formation.

Technical Field

The invention relates to a quantitative characterization method for longitudinal heterogeneous characteristics of a hydrocarbon source rock in a stratum, and belongs to the technical field of petroleum geological exploration and development.

Background

in formations dominated by source rocks, the source rocks tend to be distributed dispersedly in the longitudinal direction. A longitudinally continuous set of source rocks often see fine bedding or texture structures, either composed of different lithologies or composed of different colors. Since these different striated source rocks have large differences in organic carbon content, which causes heterogeneity in the longitudinal direction of the source rocks, studies on source rocks are required to characterize the longitudinal heterogeneity.

In the existing hydrocarbon source rock description work, due to data limitation, the whole set of hydrocarbon source rock is often used as a whole and is characterized by using uniform parameters (such as average organic matter abundance, maturity and the like) in the longitudinal direction. However, because the maturity of the source rocks is different in the longitudinal direction, particularly when the thickness of a set of source rocks is large, the thermal evolution degree of the top and the bottom of the set of source rocks is very different, so that the hydrocarbon production rate is very different, at this time, the hydrocarbon production amount calculated by using the hydrocarbon production rate of a certain point or a plurality of points to replace the hydrocarbon production rate of the whole set of source rocks is very large in error, and the longitudinal distribution position and the continuous (dispersive) distribution condition of the source rocks in the stratum cannot be expressed through the average value. Therefore, when describing the characteristics of the source rock, the longitudinal heterogeneous characteristics of the source rock, like the abundance of organic matters of the source rock, should be one of the key parameters reflecting the attributes of the source rock, and should be paid attention.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a method for quantitatively characterizing longitudinal heterogeneous characteristics of source rocks in a formation, which is capable of quantitatively describing longitudinal distribution characteristics of source rocks of different qualities (same type in the longitudinal direction, and different abundances) in the formation, so as to easily, intuitively, and accurately perform evaluation of the source rocks in the formation.

In order to achieve the purpose, the invention adopts the following technical scheme: a quantitative characterization method for longitudinal heterogeneous characteristics of a hydrocarbon source rock in a stratum comprises the following steps: determining input parameter data; determining the number of longitudinal units and the longitudinal unit attribute of the hydrocarbon source rock in the target stratum; determining the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in the target stratum; and determining the longitudinal distribution position of the source rock in the target stratum according to the equivalent distribution index of the source rock, and determining the longitudinal dispersion degree of the source rock in the target stratum according to the dispersion coefficient of the source rock.

In one particular embodiment, a histogram of the equivalent distribution index and dispersion coefficient of the source rock across all of the target formations of the target region is determined.

In one embodiment, the principal direction of the sediment source is determined according to the sedimentary facies data, and a kriging interpolation algorithm is adopted to determine a plane distribution diagram of equivalent distribution indexes and dispersion coefficients of hydrocarbon source rocks in all target strata of the whole target area, wherein the principal direction of the kriging is the principal direction of the sediment source.

in a particular embodiment, the input parameter data includes lithology, porosity, density, and organic carbon data volumes for different depths of the target formation and the source rock.

In a specific embodiment, seismic geological inversion is carried out by utilizing seismic data of a target stratum, and lithology, density, porosity and organic carbon data volumes of different depths of the target stratum and a hydrocarbon source rock are obtained; or the lithology, density, porosity and organic carbon data volumes of different depths of the target stratum and the hydrocarbon source rock are obtained in a spatial interpolation mode by utilizing the well drilling, earthquake and structural horizon data of the target stratum; or determining lithology of different depths of the target stratum and the hydrocarbon source rock by using logging data in the drilling data, and determining density, porosity and organic carbon data volumes of different depths of the target stratum by using the logging data in the drilling data.

In a specific embodiment, the minimum value of the longitudinal step length of the target stratum is determined according to the sampling rate of the input parameter data, and the longitudinal position of the target stratum is subjected to unit division.

In a specific embodiment, determining mudstone units with organic carbon larger than the lower limit value of the organic carbon of the source rock in the longitudinal units of the target stratum as the source rock units, and determining the number of the longitudinal units of the source rock; the lower limit of the organic carbon of the source rock is 5%.

In a particular embodiment, determining longitudinal cell property values for a source rock in a target formation includes depth, density, porosity, and organic carbon data for the source rock longitudinal cells.

In a specific embodiment, firstly, determining the weighting parameter of the ith unit in the source rock, then determining the average value of the weighting parameter of the source rock, and then determining the equivalent burial depth and the equivalent distribution index of the source rock in the target stratum;

The formula for determining the weighting parameter of the ith unit in the source rock is as follows:

K_i＝C_i·ρ_i(1-Φ_i) (3)

In the formula, K_iAs a weighting parameter for the i-th cell in the source rock, C_iIs the average organic carbon content of unit i in the source rock, p_iIs the average density, phi, of units i in the source rock_iis the average porosity of unit i in the source rock.

The formula for determining the average value of the weighting parameters of the source rock is as follows:

In the formula, K is the weighted parameter average value of the hydrocarbon source rock.

The formula according to which the equivalent burial depth of the source rock in the target formation is determined is as follows:

In the formula, H_ithe bottom buried depth of the unit i in the hydrocarbon source rock is shown, and H is the equivalent buried depth of the hydrocarbon source rock in the target stratum.

The formula according to which the equivalent distribution index of the source rock in the target formation is determined is as follows:

in one embodiment, determining the dispersion distance of the source rock in the target formation, and then determining the dispersion coefficient of the source rock in the target formation;

The formula according to which the dispersion distance of the source rock in the target formation is determined is:

Wherein R is the dispersion distance of the hydrocarbon source rock in the target stratum.

The formula according to which the dispersion coefficient of the source rock in the target formation is determined is:

R_max＝2(H-H_t)(H_b-H)/L (9)

R_min＝0 (10)

In the formula, R_maxis the maximum value of the dispersion distance, R, of the hydrocarbon source rock in the target stratum_minIs the minimum value of the dispersion distance of the hydrocarbon source rock in the target stratum, L is the thickness of the target stratum, H_bis the bottom buried depth of the target formation, H_tthe top buried depth of the target formation.

Due to the adoption of the technical scheme, the invention has the following advantages: according to the invention, by calculating the equivalent distribution index and the dispersion coefficient of the source rocks, the longitudinal spreading conditions of the source rocks with different qualities in the target stratum can be scientifically, reasonably and quantitatively reflected, so that the expected effect can be rapidly realized; the longitudinal distribution characteristics of the source rocks in the target stratum are basic attributes for describing the distribution of the source rocks in the target stratum, and are important research contents in related work of source rock evaluation, resource evaluation and basin simulation.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solution in the embodiments of the present invention, the following briefly introduces the drawings required in the description of the embodiments:

FIG. 1 is a schematic flow diagram of an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a formation mudstone organic carbon content data volume obtained by seismic inversion in an embodiment of the invention;

FIG. 3 is a schematic diagram of the structure of a formation mudstone spatial distribution data volume obtained by modeling in an embodiment of the invention;

FIG. 4 is a log of an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an equal-step stratigraphic unit obtained by meshing in one embodiment of the present invention;

FIG. 6 is a well-joining column diagram for a broken-down multiple-hole well in the Songliao basin in an embodiment of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.

as shown in FIG. 1, the quantitative characterization method for the longitudinal heterogeneous characteristics of the source rock, provided by the invention, comprises the following steps:

1) Determining input parameter data

and determining a target stratum region, and selecting a target stratum in the target stratum region, wherein a drilling well is arranged on the target stratum. Input parameter data is determined, the input parameter data including lithology, density, porosity, and organic carbon data volumes for different depths of a target formation and a hydrocarbon source rock (formed in the target formation). The organic carbon content of the source rock is 5% or more. The data volume format is a space equidistant discrete point format, and any target stratum in the target stratum region is converted into an equidistant data format in the longitudinal direction (depth direction). Wherein the time domain data volume has to be converted to the depth domain data volume by time depth.

in a specific embodiment, seismic data of a target stratum is obtained, and lithology, density, porosity and organic carbon data volumes of different depths of the target stratum and a hydrocarbon source rock are obtained after seismic geological inversion is carried out by using the seismic data (as shown in fig. 2, B203 in fig. 2 corresponds to # in fig. 6, and B2 in fig. 2 corresponds to # in fig. 6). And the lithological data volumes of the target stratum and the hydrocarbon source rock at different depths are obtained by seismic lithological inversion. And the organic carbon, porosity and density data volumes of the target stratum and the hydrocarbon source rock are obtained by seismic parameter inversion.

In one embodiment, well drilling, seismic and structural horizon data of a target stratum are acquired, and lithology, density, porosity and organic carbon data volumes (shown in fig. 3) of different depths of the target stratum and a hydrocarbon source rock are obtained through a spatial interpolation mode.

In a particular embodiment, the well data includes log data and well log data for wells drilled on any target formation within the target formation region. And determining lithology of the target stratum and the hydrocarbon source rock at different depths by using the logging data, and acquiring density, porosity and organic carbon data volumes (shown in figure 4) of the target stratum at different depths by using the logging data. The target formation is set in-plane to point data (multiple wells in the target formation zone appear as multiple scattered points) and longitudinally in equally spaced steps.

In one embodiment, the target formations are arranged in a regular rectangular grid in plan and are arranged longitudinally in equally spaced steps (as shown in FIG. 5).

In a preferred embodiment, the logging data records a lithology in 1 meter steps.

In a preferred embodiment, the target formation is mudstone.

2) determining the number of longitudinal cells of the target formation and the source rock, and determining longitudinal cell properties

And determining the minimum value of the longitudinal step length of the target stratum according to the sampling rate of the input parameter data. And then, determining the number of longitudinal units of the target stratum according to the thickness of the target stratum.

The number of longitudinal units of the source rock is determined according to the content of the organic carbon in the source rock (the longitudinal units refer to mudstone units with organic carbon larger than the lower limit of the organic carbon in the source rock in the target stratum, and the lower limit of the organic carbon in the source rock is 5%). The attribute values of the longitudinal units of the source rocks comprise depth, lithology, density, porosity and organic carbon value data corresponding to the longitudinal units of the source rocks.

The calculation formula according to which the number of longitudinal units of the target formation is determined is as follows:

N＝L/h (1)

L＝H_b-H_t (2)

n≤N (3)

Wherein N is the number of longitudinal units of the target stratum, L is the thickness of the target stratum, and H_bIs the bottom buried depth of the target formation, H_tThe top buried depth of the target stratum is defined, h is the minimum value of the longitudinal step length of the target stratum, and n is the number of longitudinal units of the hydrocarbon source rock. When n is 0, the target stratum has no hydrocarbon source rock, and when L is 0, the target stratum has zero thickness.

In one embodiment, the sampling rate of the input parameter data is determined to be m, and the minimum value of the longitudinal step size of the target formation is an integer multiple of 1/m. The minimum value of the longitudinal step of the target stratum can be set according to actual needs.

In a preferred embodiment, the size of the longitudinal step minimum of the target formation is equal to 1/m.

3) determining equivalent distribution index and dispersion coefficient of hydrocarbon source rock in target stratum

And determining the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in the target stratum. And determining the distribution position of the source rock in the longitudinal direction of the target stratum according to the equivalent distribution index of the source rock. And determining the discrete degree of the source rock in the longitudinal direction of the target stratum according to the dispersion coefficient of the source rock.

Determining weighted parameters of unit i in source rock

the source rock weight parameter refers to the product of the source rock organic carbon content (mass percent of the source rock organic carbon per unit mass), the source rock density and the volume percent of the source rock skeleton, and the reaction unit volume of the source rock organic matter content (mass percent of the source rock organic carbon per unit volume).

The formula for determining the weighting parameter of the ith unit in the source rock is as follows:

K_i＝C_i·ρ_i(1-Φ_i) (3)

In the formula, K_ias a weighting parameter for the i-th cell in the source rock, C_iIs the average organic carbon content of unit i in the source rock, p_iIs the average density of units i in the source rock (average rock skeleton density), Φ_iIs the average porosity of unit i in the source rock.

Determining weighted parameter average value of source rock

the weighted parameter average value of the source rock refers to the weighted parameter average value of each longitudinal unit of the source rock in the target stratum.

The formula for determining the average value of the weighting parameters of the source rock is as follows:

In the formula, K is the weighted parameter average value of the hydrocarbon source rock.

Determining equivalent burial depth of hydrocarbon source rock in target stratum

The equivalent burial depth of the source rock is the average burial depth of the weighted parameters of the source rock in the target stratum, and reflects the average value of the burial depth of the source rock in the target stratum.

The formula according to which the equivalent burial depth of the source rock in the target formation is determined is as follows:

In the formula, H_iThe bottom burial depth of the unit i in the hydrocarbon source rock.

Determining equivalent distribution index of hydrocarbon source rock in target stratum

The equivalent distribution index of the source rock in the target stratum refers to the longitudinal average distribution position of the source rock in the target stratum (considering the weighting parameters of the source rock), and quantitatively reflects the longitudinal distribution (upper part or lower part) of the source rock in the target stratum.

The formula according to which the equivalent distribution index of the source rock in the target formation is determined is as follows:

Determining the dispersion distance of the hydrocarbon source rock in the target stratum

The dispersion distance of the source rock in the target stratum refers to the average distance between the source rock developing at different longitudinal positions in the target stratum (considering the weighting parameters of the source rock) and the equivalent buried depth position of the source rock. Theoretically, the dispersion distance of the source rock is maximized when the source rock is evenly distributed to the top and bottom of the target formation. When the source rock is intensively distributed at one section of the target stratum, the dispersion distance of the source rock reaches a minimum value.

the formula according to which the dispersion distance of the source rock in the target formation is determined is:

Wherein R is the dispersion distance of the hydrocarbon source rock in the target stratum.

Sixthly, determining the dispersion coefficient of the hydrocarbon source rock in the target stratum

And quantitatively reflecting the discrete degree of the longitudinal distribution of the source rocks by the ratio of the dispersion distance of the source rocks in the target stratum to the difference between the maximum value and the minimum value of the theoretical dispersion distance of the source rocks.

The formula according to which the dispersion coefficient of the source rock in the target formation is determined is:

R_max＝2(H-H_t)(H_b-H)/L (9)

R_min＝0 (10)

in the formula, R_maxIs the maximum value of the dispersion distance, R, of the hydrocarbon source rock in the target stratum_minIs the minimum value of the dispersion distance of the source rock in the target formation.

When n is 0 or L is 0, the average value of the weighting parameters of the source rock, the equivalent burial depth, the equivalent distribution index, the dispersion distance and the dispersion coefficient are meaningless.

4) Repeating the step 2) and the step 3) to obtain the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in all target strata in the whole target area

5) Determining a histogram of equivalent distribution indices and dispersion coefficients of source rocks in all target formations throughout a target region

and determining the main direction of a sediment source according to the sedimentary facies data, and determining the plane distribution diagram of the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock in all target strata of the whole target area by adopting a Krigin interpolation algorithm. Wherein the main direction of the kriging is the direction of the deposit source.

An embodiment will be described below

In the embodiment, quantitative characterization is carried out on the longitudinal distribution of the XX fault-trap XX-layer hydrocarbon source rock in the target area XX of the Songliao basin, 10 drilling wells with major fault-trap points in the target area XX of the Songliao basin are selected in a simulated mode, and the equivalent distribution index and the dispersion coefficient of the hydrocarbon source rock are calculated according to 2 layers.

firstly, logging lithology data and logging curves of the 10 drilled wells are obtained, the density, the porosity and the organic carbon of each drilled well at different longitudinal depths of a target interval are predicted by a delta logR method, wherein the logging data is 1 sampling rate per meter, the logging prediction data is 8 sampling rates per meter, and an identifiable lithology unit is determined to be 1 meter according to the research precision requirement, so that a target stratum is divided by adopting a 1 meter step length, and a drilling well combination profile is determined (as shown in fig. 6). Next, the density, porosity and organic carbon data for each longitudinal unit lithology and source rock for each well are determined. Then, determining the weighted parameters of each longitudinal unit of the source rock, determining the weighted average parameters of each longitudinal unit of the source rock, determining the equivalent burial depth and the equivalent distribution index of the source rock, and determining the dispersion distance and the dispersion coefficient of the source rock. The equivalent distribution index and dispersion coefficient of the upper and lower hydrocarbon source rocks of the 10 drilled wells in the target area are calculated (as shown in table 1).

TABLE 1 equivalent distribution index and dispersion coefficient of upper and lower hydrocarbon source rocks of 10-hole drilling in target area

although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.