A method for constructing an isochronous stratigraphic framework in the platform-trough facies region based on underground and outcrop data

Abstract

The present invention discloses a method for constructing an isochronous stratigraphic framework for platform-trough phases based on underground and outcrop data, including: based on drilling and field profile data, guided by the principle of sequence stratigraphy, through microstructural analysis, spectrum analysis, and macro-micro combination of technical means, clarifying rock types and development characteristics, determining rock phase sequence combinations, establishing a matching relationship between rocks and logging curves, and combining the measured radioactive curve data of field profiles to construct an isochronous stratigraphic framework across phases on the surface. The advantages of the present invention are: not only solving and making up for the problem of insufficient data, but also being able to construct an isochronous stratigraphic framework for carbonate rock strata with low seismic resolution and thin stratum thickness, providing data support for paleo-geomorphic restoration and lithofacies paleo-geographic restoration, thereby improving exploration knowledge and reducing exploration risks.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration and development, and in particular to a method for constructing an isochronous stratigraphic framework in a platform-trough phase region based on the combination of downhole and outcrop data. Background Art

[0002] The isochronous stratigraphic framework is the basis of various geological studies on oil and gas field development, and it has important practical exploration guidance significance for sedimentary understanding and reservoir prediction. The platform-trough facies area is not only a favorable zone for reef and beach lithologic oil and gas reservoir closure, but also a sedimentary facies transition zone. It is controlled by complex geological background and shows obvious phase change characteristics. Therefore, the accurate construction of the isochronous stratigraphic framework of the platform-trough facies area is directly related to the deepening of sedimentary understanding and the decision-making of future oil and gas exploration directions. At present, the isochronous stratigraphic framework of the platform-trough facies area is mainly based on seismic and drilling data, but the seismic accuracy is limited and the recognition degree is low, and the data of drilling encountering this transition phase are relatively few, resulting in differences in the type and division scheme of isochronous interfaces, and even questioning whether the two phase belts are developed. Therefore, it is urgent to supplement new data, construct the isochronous stratigraphic framework of the platform-trough facies area, clarify the type and division scheme of isochronous interfaces, and solve the disputes and doubts in the current understanding. Previous researchers have conducted extensive research on the platform-trough facies area and found that it is exposed in multiple field sections and is relatively well preserved. This not only solves and makes up for the problem of insufficient data, making the constructed isochronous stratigraphic framework of the platform-trough facies area more accurate, but also provides new ideas for the exploration and geological understanding of the platform-trough facies area. Summary of the invention

[0003] In view of the defects of the prior art, the present invention provides a method for constructing an isochronous stratigraphic framework in a platform-trough phase region based on downhole and outcrop data.

[0004] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0005] A method for constructing an isochronous stratigraphic framework for platform-trough facies based on downhole and outcrop data comprises the following steps:

[0006] 1) Based on field geological surveys, select platform-trough field outcrops with complete top and bottom exposures and phase change characteristics, and conduct detailed observation and measurement of profiles, including: identification of typical lithology interfaces in the field, measurement of sedimentary characteristics, rock types, true thickness of strata, and high-precision and intensive sampling; based on the development characteristics of rock types and the requirements of natural gamma ray measurement intervals, combined with profile development characteristics, draw survey lines perpendicular to the profile, calibrate and number the measurement points of the profile, and make records;

[0007] 2) According to the calibrated measuring points in the field outcrop, the natural gamma instrument is used to measure the GR, U, TH, and K data, and the data are processed and analyzed. According to the layer number and depth, the outcrop GR curve and U / TH curve are established with a measurement accuracy of 0.2m. The GR curve and U / TH curve of the well logging at the surrounding wells are compared to analyze the differences in numerical values ​​and vertical changes;

[0008] 3) According to the distribution characteristics of the measuring points, rock samples are selected, rock thin sections are ground, and the rock thin sections are observed and identified using a single polarizing microscope and micro-structure analysis technology. According to the rock classification standards and combined with the macroscopic characteristics of the rock, the rock type and development characteristics are clarified; according to the rock sedimentary characteristics, a combination of macro and micro methods are used to determine the sedimentary microfacies type and the rock phase sequence combination.

[0009] 4) Based on field outcrop data, rock thin section data, GR and U / TH curves, field outcrop sequence interface identification is carried out to determine the characteristics and identification marks of different interfaces, and to divide the single-section longitudinal stratigraphic sequence.

[0010] 5) Based on the distribution of the field profile, combined with the core sampling completeness and development characteristics, the core sampling wells around the profile are selected, and detailed core observations and sampling grinding are carried out. The rock types are summarized by using micro-structure analysis and macro-micro combined technical means, and compared with the rock types of the field profile to clarify the differences between them.

[0011] 6) Based on logging curves and imaging logging data, combined with the macro-micro development characteristics of rocks and their rock-electrical correspondence, spectrum analysis and macro-micro combined technical means are used to perform core retrieval for coring and logging, and establish a matching relationship between rocks and logging curves and imaging logging.

[0012] 7) Based on the matching relationship between rocks and logging curves, guided by the principles of sequence stratigraphy, combined with the macro and micro characteristics of the core, the spectrum analysis method is used to identify the single well sequence interface, clarify the development characteristics of different sequences and logging curves, imaging logging, and divide the vertical stratigraphic sequence of the single well.

[0013] 8) Based on the existing single-well and single-section sequence framework, according to the plane distribution position, the spectrum analysis technology is used to construct the isochronous stratigraphic framework across the surface and the underlying phases.

[0014] Furthermore, step 4) the single-section vertical stratigraphic sequence comprises:

[0015] The field characteristics of typical sequence interfaces in platform facies are as follows:

[0016] Above the interface, thin-layered carbonate rocks containing mud are dominant. If the phase changes to the trough phase, the thin-layered carbonate rocks containing mud, shale, and siliceous rocks in deeper water are dominant.

[0017] Below the interface are thick-massive carbonate rocks, in which karst systems and breccias are sometimes seen;

[0018] The curve characteristics of typical sequence interfaces in platform facies are as follows:

[0019] The GR curve is positively shifted above the interface. If the strata on the boundary are transformed into trough phase, the U / TH curve will have a positive shift, which means that the shift of the GR curve is mainly contributed by U, where U represents organic matter and TH represents clay component. The GR value is smaller below the interface, mostly showing boxed low values.

[0020] Further, step 7) the vertical stratigraphic sequence of a single well includes:

[0021] The curve characteristics of typical sequence interfaces in platform facies are as follows:

[0022] GR is positively offset above the interface. If the strata on the boundary line are transformed into trough phase, the U / TH curve will be obviously positively offset. The positive offset of GR is mainly contributed by U;

[0023] The GR value is small below the interface, mostly showing box-packed low values. The imaging logging shows that the sequence interface is a typical lithology and lithofacies transition surface. Below the interface are mostly bright high-resistance massive carbonate rocks, with porphyritic dark low-resistance karst systems visible. Above the interface are thin-layered deposits with high mud content, low overall resistance, and dark color.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] It not only solves and makes up for the problem of insufficient data, but also can construct an isochronous stratigraphic framework for carbonate strata with low seismic resolution and thin strata thickness, provide data support for paleo-geomorphology restoration and lithofacies paleogeography restoration, thereby improving exploration understanding and reducing exploration risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the steps of the present invention.

[0027] Figure 2 Schematic diagram of field profile measurement and core macro-microscopic observation of an embodiment of the present invention; A is an outcrop profile, B is an outcrop profile measurement, C is a drilling core; D is a microscopic photo under a single polarizing microscope;

[0028] Figure 3 A comparison chart of the radioactivity data of a field profile and its adjacent drilling and logging data in an embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of the field contour curve characteristics and lithological characteristics of the Qixia Formation-Maokou Formation (SQ1) in an embodiment of the present invention;

[0030] Figure 5Schematic diagram of well logging curve characteristics and lithology characteristics of SQ1-SQ2 in the in-situ well logging curve of the embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of field line curve characteristics and lithological characteristics of Example SQ2-SQ3 of the present invention;

[0032] Figure 7 This is a schematic diagram of the GR curve characteristics and lithological characteristics of the Maokou Formation (SQ3)-Wujiaping Formation field boundary line in an embodiment of the present invention;

[0033] Figure 8 A single-section sequence stratigraphic diagram is established for the embodiment of the present invention;

[0034] Fig. 9 Schematic diagram of the well logging curve and imaging well logging characteristics of the Qixia Formation-Maokou Formation (SQ1) in the embodiment of the present invention;

[0035] Fig.10 This is a schematic diagram of the characteristics of the SQ1-SQ2 in-situ well logging curve in an embodiment of the present invention;

[0036] Fig.11 This is a characteristic schematic diagram of the SQ2-SQ3 in-situ well logging curve of an embodiment of the present invention;

[0037] Fig.12 This is a schematic diagram of the characteristics of the in-situ well logging curve of the Maokou Formation (SQ3)-Wujiaping Formation in an embodiment of the present invention;

[0038] Fig.13 This is a schematic diagram of imaging logging characteristics of each sequence interface during drilling according to an embodiment of the present invention;

[0039] Fig.14 A schematic diagram of a single well sequence stratigraphic sequence is established for the embodiment of the present invention;

[0040] Fig.15 A schematic diagram of an isochronous stratigraphic framework across phase zones on the surface and in the underside of the earth is established for an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0042] A method for constructing an isochronous stratigraphic framework for platform-trough facies based on downhole and outcrop data comprises the following steps:

[0043] 1) Based on field geological surveys, select field outcrops (platforms, troughs) with complete top and bottom exposures and phase change characteristics for detailed profile observation and measurement, including field typical lithology interface identification, sedimentary characteristics, rock types, measurement of true stratum thickness, high-precision and intensive sampling, etc.; based on the rock type development characteristics and the requirements for the natural gamma ray measurement interval (no less than 3 points per rock unit thickness), combined with the profile development characteristics, draw survey lines perpendicular to the profile, calibrate and number the profile measurement points, and make records.

[0044] 2) According to the calibrated measuring points in the field outcrops, the natural gamma instrument is used to mainly measure the GR, U, TH, and K data, and the data are processed and analyzed. According to the layer number and depth, the outcrop GR curve and U / TH curve are established with a measurement accuracy of 0.2m. The GR curve and U / TH curve of the well logging at the peripheral wells are compared to analyze the differences in numerical values ​​and vertical changes (see Appendix). Figure 2 );

[0045] 3) According to the distribution characteristics of the measuring points, rock samples are selected, rock slices are ground, and the rock slices are observed and identified using a single polarizing microscope and microstructure analysis technology. According to the rock classification standards and combined with the macroscopic characteristics of the rock, the rock type and development characteristics are clarified (see Appendix). Figure 3 ; Based on the rock sedimentary characteristics, a combination of macro and micro methods is used to determine the sedimentary microfacies type and the rock phase sequence combination.

[0046] 4) Based on the field outcrop data, rock thin section data, GR and U / TH curves, the outcrop sequence interface is identified in the field, and the characteristics and identification marks of different interfaces are determined ( Figures 4 to 7 ) and divide the single-section longitudinal stratigraphic sequence (attached Figure 8 ). The field characteristics of a typical sequence interface in the platform phase area are that above the interface, thin-layered muddy carbonate rocks are dominant. If the phase changes to the trough phase, the thin-layered muddy carbonate rocks, shale and siliceous rocks of deeper water are dominant. Below the interface, there are thick-layered massive carbonate rocks, and sometimes karst systems and breccias are developed. The curve characteristics of a typical sequence interface in the platform phase area are: above the interface, the GR curve is positively offset. If the strata on the boundary are transformed into the trough phase, the U / TH curve is positively offset, which means that the offset of the GR curve is mainly contributed by U (U represents organic matter and TH represents clay components). Below the interface, the GR value is small, mostly showing low box values.

[0047] 5) Based on the distribution of the field profile, combined with the core sampling completeness and development characteristics, the core sampling wells around the profile are selected, and detailed core observations and sampling grinding are carried out. The rock types are summarized by using micro-structure analysis and macro-micro combined technical means, and compared with the rock types of the field profile to clarify the differences between them.

[0048] 6) Based on logging curves and imaging logging data, combined with the macro-micro development characteristics of rocks and their rock-electrical correspondence, spectrum analysis and macro-micro combined technical means are used to perform core retrieval for coring and logging, and establish a matching relationship between rocks and logging curves and imaging logging.

[0049] 7) Based on the matching relationship between rocks and well logging curves, guided by the principles of sequence stratigraphy, combined with the macro and micro characteristics of the core, the spectrum analysis method is used to identify the interface of the single well sequence, and to clarify the development characteristics of different sequences, well logging curves, and imaging logging ( Figures 9 to 13 ) and divide the vertical stratigraphic sequence of a single well ( Fig.14 ). The curve characteristics of a typical sequence interface in the platform phase area are: GR is positively offset above the interface. If the strata on the boundary are transformed into the trough phase, the U / TH curve is obviously positively offset. The GR positive offset is mainly contributed by U. The GR value below the interface is small, mostly box-packed low values. It can be seen from the imaging logging that the sequence interface is a typical lithology and lithofacies transition surface. Below the interface are mostly bright high-resistance massive carbonate rocks, and patchy dark low-resistance karst systems can be seen. Above the interface are thin-layered deposits with high mud content, low overall resistance, and dark color.

[0050] 8) Based on the existing single-well and single-section sequence framework, and according to the plane distribution position, the spectrum analysis technology is used to construct the surface and underground cross-phase isochronous stratigraphic framework ( Fig.15 ).

[0051] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the implementation methods of the present invention, and should be understood that the protection scope of the present invention is not limited to such special statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for constructing an isochronous stratigraphic framework for platform-trough facies based on downhole and outcrop data, characterized in that: The following steps are involved: 1) Based on field geological surveys, select platform-trough field outcrops with complete top and bottom exposures and phase change characteristics, and conduct detailed observation and measurement of profiles, including: identification of typical lithology interfaces in the field, measurement of sedimentary characteristics, rock types, true thickness of strata, and high-precision and intensive sampling; based on the development characteristics of rock types and the requirements of natural gamma ray meter measurement intervals, combined with profile development characteristics, draw survey lines perpendicular to the profile, calibrate and number the measurement points of the profile, and make records; 2) According to the calibrated measuring points in the field outcrops, the natural gamma instrument is used to measure the GR, U, TH, and K data, and the data are processed and analyzed. According to the layer number and depth, the outcrop GR curve and U / TH curve are established with a measurement accuracy of 0.2m. The GR curve and U / TH curve of the well logging at the surrounding wells are compared to analyze the differences in numerical values ​​and vertical changes; 3) According to the distribution characteristics of the measuring points, rock samples are selected, rock thin sections are ground, and the rock thin sections are observed and identified using a single polarizing microscope and microscopic structural analysis technology. According to the rock classification standards and combined with the macroscopic characteristics of the rock, the rock type and development characteristics are clarified; according to the rock sedimentary characteristics, the macroscopic and microscopic combined methods are used to determine the sedimentary microfacies type and the rock phase sequence combination; 4) Based on the outcrop data, rock thin section data, GR and U / TH curves, the outcrop sequence interface is identified in the field, the characteristics and identification marks of different interfaces are determined, and the vertical stratigraphic sequence of a single section is divided; 5) According to the distribution of the field profile, combined with the core sampling completeness and development characteristics, the core wells around the profile are selected, and detailed core observation and sampling grinding are carried out. The rock types are summarized by using micro-structure analysis and macro-micro combination technical means, and compared with the rock types of the field profile to clarify the differences between them; 6) Based on logging curves and imaging logging data, combined with the macro-micro development characteristics of rocks and their rock-electrical correspondence, spectrum analysis and macro-micro combined technical means are used to perform core retrieval for coring and logging, and establish a matching relationship between rocks and logging curves and imaging logging; 7) Based on the matching relationship between rocks and well logging curves, guided by the principles of sequence stratigraphy, combined with the macro and micro characteristics of the core, the spectrum analysis method is used to identify the interface of the single well sequence, clarify the development characteristics of different sequences and well logging curves, imaging logging, and divide the vertical stratigraphic sequence of the single well; 8) Based on the existing single-well and single-section sequence framework, according to the plane distribution position, the spectrum analysis technology is used to construct the isochronous stratigraphic framework across the surface and the underlying phases.

2. The construction method according to claim 1, characterized in that: Step 4) Single-section vertical stratigraphic sequence includes: The field characteristics of typical sequence interfaces in platform facies are as follows: Above the interface, thin-layered carbonate rocks containing mud are dominant. If the phase changes to the trough phase, the thin-layered carbonate rocks containing mud, shale, and siliceous rocks in deeper water are dominant. Below the interface are thick-massive carbonate rocks, in which karst systems and breccias are sometimes seen; The curve characteristics of typical sequence interfaces in platform facies are as follows: The GR curve is positively shifted above the interface. If the strata on the boundary are transformed into trough phase, the U / TH curve will have a positive shift, which means that the shift of the GR curve is mainly contributed by U, where U represents organic matter and TH represents clay component. The GR value is smaller below the interface, mostly showing boxed low values.

3. The construction method according to claim 1, characterized in that: Step 7) The vertical stratigraphic sequence of a single well includes: The curve characteristics of typical sequence interfaces in platform facies are as follows: GR is positively offset above the interface. If the strata on the boundary line are transformed into trough phase, the U / TH curve will be obviously positively offset. The positive offset of GR is mainly contributed by U; The GR value is smaller below the interface, mostly showing box-type low values; imaging logging shows that the sequence interface is a typical lithology-facies transition surface, with bright-colored high-resistance massive carbonate rocks below the interface, and patchy dark-colored low-resistance karst systems visible; above the interface are thin-layered deposits with a high mud content, low overall resistance, and dark color.

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