A well-to-seismic combination method for volcanic rock stage division and multi-well comparison and evaluation

Abstract

This invention discloses a method for volcanic rock phase division and multi-well comparative evaluation combining well and seismic data. Based on well logging data, core sampling data, and seismic data from volcanic rock blocks, it identifies and corrects the developmental strata of volcanic rocks. Furthermore, it extracts seismic spectral curves and creates synthetic seismic records. Then, using these synthetic seismic records, it determines the seismic response characteristics within the volcanic rock mass and characterizes the seismic phase distribution. Finally, it completes the single-well volcanic rock phase division and multi-well comparison under seismic phase constraints. This invention, by characterizing the seismic phase distribution within the volcanic rock mass of the entire region, makes subsequent single-well phase division and multi-well comparison hierarchical and constrained, solving the problem of inconsistent stratigraphic correlation in the past and providing reliable technical support for the selection of potential targets.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development, and in particular to a method for evaluating multi-well comparison and phase division of volcanic rock oil and gas reservoirs. Background Technology

[0002] Volcanic rock oil and gas reservoirs were first discovered in 1887 in the San Juan Basin, California, USA. In China, they were first discovered in 1957 on the northwestern edge of the Junggar Basin. In 2001, Daqing Oilfield Company obtained high-yield industrial oil and gas flows from volcanic rocks during exploration in the Xujiaweizi Depression of the Songliao Basin, breaking the traditional notion that volcanic rocks were off-limits for oil and gas exploration and demonstrating the enormous potential of volcanic rock oil and gas reservoirs. Over the past 60 years, volcanic rock oil and gas reservoirs have been discovered in 11 oil and gas basins, including the Bohai Bay, Songliao, Junggar, Erenhot, and Santanghu basins, with proven oil reserves of hundreds of millions of tons.

[0003] Multi-well correlation and phase classification of volcanic rocks are crucial for improving volcanic rock productivity. Good multi-well correlation and accurate phase classification lead to clear potential targets and better development results; conversely, poor correlation and inaccurate phase classification result in unclear potential targets and poor development results. Current research on volcanic oil and gas reservoirs mainly focuses on mineral composition, chemical composition, rock structure, facies and facies models, and volcanic structures. It primarily concentrates on lithology, lithofacies, and reservoir studies at the exploration scale. However, these studies have the following limitations: firstly, they cannot address the rapid abrupt changes in lithology within volcanic rocks during multi-well correlation; secondly, they cannot achieve phase classification of volcanic rock formations across multiple wells or isochronous correlation of volcanic reservoirs between wells. Therefore, in order to better develop volcanic rock oil and gas reservoirs, it is necessary to combine seismic and well logging data, and accurately characterize the formation stages of volcanic rock single wells through seismic characterization and single-well comparison. This will enable the comparison of volcanic rock reservoirs between different wells, thereby more scientifically and rationally elucidating the reservoir distribution characteristics of volcanic rocks and providing a better basis for solving the design of development schemes for volcanic rock oil and gas reservoirs and subsequent scheme adjustments. Summary of the Invention

[0004] The purpose of this invention is to provide a method for multi-level volcanic rock phase division and multi-well comparison that combines well and seismic analysis to solve the above-mentioned technical problems, thereby filling the gap in the development of volcanic rock oil and gas reservoirs.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for well-seismic combined volcanic rock phase division and multi-well comparative evaluation, comprising the following steps:

[0006] A. Identifying the developmental sections of volcanic rocks in a single well

[0007] A1. Collect basic data on volcanic rocks

[0008] Collect core observation data, cuttings logging data, well logging curve data, and 3D seismic data from cored wells; among which, well logging curve data includes natural gamma ray logging curves, neutron logging curves, sonic transit time logging curves, density logging curves, and bottom 2.5m gradient resistivity logging curves. Natural gamma ray logging curves are abbreviated as GR curves, neutron logging curves as CN curves, sonic transit time logging curves as AC curves, and density logging curves as DEN curves.

[0009] A2. Identifying volcanic rock development zones

[0010] Observe the core samples from the core wells to identify the volcanic rock and mudstone development zones; standardize the AC, GR, DEN, and CN curves of the volcanic rock and mudstone, and establish a well logging curve cross-plot with the AC curve as the abscissa and the GR, CN, and DEN curves as the ordinates respectively. From the cross-plot, obtain the identification criteria for the well logging curves of the volcanic rock and mudstone, and perform lithological identification on the non-core sections and non-core wells according to the identification criteria.

[0011] B. Creating single-well synthetic seismic records

[0012] B1. Analyze the seismic spectrum of volcanic rock formations and generate seismic wavelets.

[0013] Extract the spectral curves of seismic records from volcanic rock strata, analyze the dominant frequency of the volcanic rock seismic data based on the spectral curves, and extract the Ricker wavelet W(t) of the dominant frequency as the seismic wavelet:

[0014] W(t)=exp(-(2π×fm×t) 2 )×cos(2×π×fm×t)

[0015] In the formula, t represents time; fm is the main frequency.

[0016] B2. Production of single-well synthetic seismic records

[0017] The reflection coefficient R(t) of a single well is calculated using the acoustic transit time and the compensated density logging curve, and the seismic wavelet W(t) is convolved to produce a single-well synthetic seismic record F(t).

[0018] F(t) = R(t) × W(t)

[0019] In the formula, F(t) represents the seismic record; W(t) represents the seismic wavelet; and R(t) represents the reflection coefficient.

[0020]

[0021] R i =(Z i -Z i-1 ) / (Z i +Z i-1 )

[0022] Z i =v i ×ρ i

[0023] In the formula, R i Z is the reflection coefficient at depth i; i Acoustic impedance at depth of layer i; v i Let ρ be the acoustic time difference at depth i; i H represents the depth compensation density of the i-th layer; i Let i be the depth of the i-th layer;

[0024] C. Determine the seismic response characteristics within the volcanic rock mass and characterize the phased distribution of earthquake magnitudes.

[0025] C1. Seismic tracking of the top and bottom interfaces and outer contours of volcanic rock masses.

[0026] Using the results of single-well synthetic records, the seismic response intervals at the top and bottom of the volcanic rock were identified, and the amplitude response characteristics of the volcanic rock mass and the overlying and underlying sedimentary rocks were obtained. Combined with the seismic amplitude variation characteristics, the external contour of the volcanic rock mass in the three-dimensional seismic body was characterized.

[0027] C2. Identifying the internal structure of volcanic rock masses

[0028] Guided by the seismic response characteristics of the chaotic reflection volcanic conduit phase, the medium-to-weak amplitude volcanic eruption phase, and the strong amplitude medium-to-high continuity volcanic overflow phase, the internal structural characteristics of the volcanic rock mass are identified; and the different times of the same direction axis of the earthquake are used as the stages of the earthquake magnitude within the volcanic rock mass.

[0029] D. Classification of single-well volcanic rock periods under the constraint of seismic periods

[0030] D1. The sediments from the intervolcanic period are mudstone, and mudstone is used as the boundary for dividing the volcanic rock phases in a single well;

[0031] D2. Using mudstone interlayers as the dividing interface, complete the single-well volcanic rock period division and multi-well comparison under the constraint of seismic period.

[0032] The beneficial effects of this invention are:

[0033] 1. Solved the problems of isochronous correlation of single-well volcanic rocks and the internal phase division of volcanic rock bodies.

[0034] 2. A method for dividing the development stages of volcanic rock oil and gas reservoirs into phases and for multi-well correlation was developed;

[0035] 3. To provide geological basis and solutions for the efficient development of volcanic rock oil and gas reservoirs; Attached Figure Description

[0036] Figure 1This is a flowchart of the well-seismic combined method for hierarchical volcanic rock phase division and multi-well comparison according to the present invention.

[0037] Figure 2 This is a natural gamma GR-acoustic time difference AC intersection diagram according to an embodiment of the present invention.

[0038] Figure 3 It is a lithology identification map of non-cored well Jun 21-23 based on the logging response characteristics of volcanic rocks.

[0039] Figure 4 This is a spectral curve analysis diagram of a volcanic rock layer.

[0040] Figure 5 These are composite seismic records from a single well in a 3D seismic body (where (a) is the composite seismic record from well Li18, and (b) is the composite seismic record from well Jun23-25).

[0041] Figure 6 It is a top surface structural diagram of the volcanic rock eruption mode obtained from the seismic response inside the rock mass.

[0042] Figure 7 It is a volcanic eruption channel map (variance attribute) of a single-well synthetic seismic record, which is made based on sonic transit time logging curves and compensated density logging curves.

[0043] Figure 8 It is a comparative profile of earthquake periods combining well and seismic data.

[0044] Figure 9 It is a single-well period division profile under the constraint of seismic period.

[0045] Figure 10 This is a diagram showing the results of the phase division of single wells 23-25. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0047] like Figure 1 As shown, the well-seismic combined method for volcanic rock phase division and multi-well comparative evaluation of the present invention includes the following steps:

[0048] A. Identifying the developmental sections of volcanic rocks in a single well

[0049] A1. Collect basic data on volcanic rocks

[0050] Collect core observation data, cuttings logging data, well logging curve data, and 3D seismic data from cored wells; among which, well logging curve data includes natural gamma ray logging curves, neutron logging curves, sonic transit time logging curves, density logging curves, and bottom 2.5m gradient resistivity logging curves. Natural gamma ray logging curves are abbreviated as GR curves, neutron logging curves as CN curves, sonic transit time logging curves as AC curves, and density logging curves as DEN curves.

[0051] A2. Identifying volcanic rock development zones

[0052] Observe the core samples from the core wells to identify the volcanic rock and mudstone development zones; standardize the AC, GR, DEN, and CN curves of the volcanic rock and mudstone, and establish a well logging curve cross-plot with the AC curve as the abscissa and the GR, CN, and DEN curves as the ordinates respectively. From the cross-plot, obtain the identification criteria for the well logging curves of the volcanic rock and mudstone, and perform lithological identification on the non-core sections and non-core wells according to the identification criteria.

[0053] B. Creating single-well synthetic seismic records

[0054] B1. Analyze the seismic spectrum of volcanic rock formations and generate seismic wavelets.

[0055] Extract the spectral curves of seismic records from volcanic rock strata, analyze the dominant frequency of the volcanic rock seismic data based on the spectral curves, and extract the Ricker wavelet W(t) of the dominant frequency as the seismic wavelet:

[0056] W(t)=exp(-(2π×fm×t) 2 )×cos(2×π×fm×t)

[0057] In the formula, t represents time; fm is the main frequency.

[0058] B2. Production of single-well synthetic seismic records

[0059] The reflection coefficient R(t) of a single well is calculated using the acoustic transit time and the compensated density logging curve, and the seismic wavelet W(t) is convolved to produce a single-well synthetic seismic record F(t).

[0060] F(t) = R(t) × W(t)

[0061] In the formula, F(t) represents the seismic record; W(t) represents the seismic wavelet; and R(t) represents the reflection coefficient.

[0062]

[0063] R i =(Z i -Z i-1 ) / (Z i +Z i-1 )

[0064] Z i =v i ×ρ i

[0065] In the formula, R i Z is the reflection coefficient at depth i; i Acoustic impedance at depth of layer i; v i Let ρ be the acoustic time difference at depth i; i H represents the depth compensation density of the i-th layer; i δ represents the depth of the i-th layer; δ is the function calculation symbol.

[0066] C. Determine the seismic response characteristics within the volcanic rock mass and characterize the phased distribution of earthquake magnitudes.

[0067] C1. Seismic tracking of the top and bottom interfaces and outer contours of volcanic rock masses.

[0068] Using the results of single-well synthetic records, the seismic response intervals at the top and bottom of the volcanic rock were identified, and the amplitude response characteristics of the volcanic rock mass and the overlying and underlying sedimentary rocks were obtained. Combined with the seismic amplitude variation characteristics, the external contour of the volcanic rock mass in the three-dimensional seismic body was characterized.

[0069] C2. Identifying the internal structure of volcanic rock masses

[0070] Guided by the seismic response characteristics of the chaotic reflection volcanic conduit phase, the medium-to-weak amplitude volcanic eruption phase, and the strong amplitude medium-to-high continuity volcanic overflow phase, the internal structural characteristics of the volcanic rock mass are identified; and the different times of the same direction axis of the earthquake are used as the stages of the earthquake magnitude within the volcanic rock mass.

[0071] D. Classification of single-well volcanic rock periods under the constraint of seismic periods

[0072] D1. The sediments from the intervolcanic period are mudstone, and mudstone is used as the boundary for dividing the volcanic rock phases in a single well;

[0073] D2. Using mudstone interlayers as the dividing interface, complete the single-well volcanic rock period division and multi-well comparison under the constraint of seismic period.

[0074] The method of the present invention will be described in detail below with reference to specific implementations:

[0075] The present invention provides a method for the phase division of volcanic rocks and multi-well comparative evaluation based on well-seismic analysis, comprising the following steps:

[0076] A: Identify the developmental section of volcanic rock in a single well

[0077] A1. Collect basic data on volcanic rocks

[0078] Core observation data from 4 cored wells in the volcanic rock block, cuttings logging data from 69 wells, well logging data (natural gamma ray logging, neutron logging, sonic transit time logging, density logging, bottom 2.5m gradient resistivity logging) from 69 wells, and 3D seismic body data from 1 well were collected.

[0079] A2. Identifying volcanic rock development zones

[0080] Based on the core observation results of the core section of the cored well, stable volcanic rocks and mudstones were identified. The AC, GR, DEN, and CN curves of the volcanic rocks and mudstones were standardized, and a well logging curve cross-plot was established with the AC curve as the abscissa and the GR, CN, and DEN curves as the ordinates, respectively. Figure 2 Based on the map, lithological identification standards were established (Table 1). Lithological identification was performed on non-core well sections and non-core wells to identify the developmental sections of volcanic rocks and mudstones in individual wells (e.g., Figure 3 );

[0081] Table 1. Criteria for Identifying Volcanic Rock Lithology

[0082]

[0083] B: Creating single-well synthetic seismic records

[0084] B1. Analyze the seismic spectrum of volcanic rock formations and generate seismic wavelets.

[0085] The seismic record spectral curves of the volcanic rock strata were extracted. Based on the spectral curve analysis, the dominant frequency of the seismic wave in the target layer was determined to be 20 Hz. Therefore, a seismic wavelet (e.g., 20 Hz) was created using 20 Hz as the reference. Figure 4 ).

[0086] W(t)=exp(-(2π×20×t) 2 )×cos(2×π×20×t)

[0087] In the formula, W(t) represents the seismic wavelet, t represents time, and fm represents the main frequency of 20Hz.

[0088] B2. Production of single-well synthetic seismic records

[0089] Calculate the reflection coefficient of a single well using sonic transit time and compensated density logging curves:

[0090] R i =(Z i -Z i-1 ) / Z i +Z i-1 )

[0091] Z i =v i ×ρ i

[0092] In the formula, R i Z is the reflection coefficient at depth i; i Acoustic impedance at depth of layer i; v i Let ρ be the acoustic time difference at depth i; i The density is calculated for the depth of the i-th layer; the calculation table for a portion of the depth in well Li 18 is as follows:

[0093]

[0094]

[0095]

[0096] The reflection coefficient R i Convolve R(t) and generate single-well synthetic seismic records F(t) (e.g.) Figure 5 )

[0097]

[0098] F(t) = R(t) × W(t)

[0099] In the formula, H i Let F(t) be the depth of the i-th layer, F(t) be the seismic record, W(t) be the seismic wavelet, and R(t) be the reflection coefficient.

[0100] C. Determine the seismic response characteristics within the volcanic rock mass and characterize the phased distribution of earthquake magnitudes.

[0101] C1. Seismic tracking of the top and bottom interfaces and outer contours of volcanic rock masses.

[0102] Using the results of single-well synthetic records, the seismic response intervals at the top and bottom of the volcanic rock were calibrated. The results showed that the volcanic rock mass exhibited strong amplitude response, while the overlying and underlying sedimentary rocks showed weak amplitude response. These seismic amplitude variation characteristics were then used to characterize the external contour of the volcanic rock mass within the three-dimensional seismic body (e.g., Figure 6 )

[0103] C2. Identifying the internal structure of volcanic rock masses

[0104] Guided by the seismic response characteristics of chaotic reflection volcanic conduit phases, medium-to-weak amplitude volcanic eruption phases, and strong amplitude medium-to-high continuity volcanic effusive phases, the internal structural features of the volcanic rock mass were identified as volcanic eruption conduits jointly controlled by three volcanic conduits (such as...). Figure 7 It also indicates that there are three different seismic axes in the same direction within the volcanic rock mass, dividing the volcanic rock mass into three seismic magnitude periods (e.g., Figure 8 )

[0105] D. Classification of single-well volcanic rock periods under the constraint of seismic periods

[0106] D1. The sediments from the intervolcanic period are mudstone, and mudstone is used as the boundary for dividing the volcanic rock phases in a single well;

[0107] D2. Using mudstone interlayers as the dividing interface, complete the division of volcanic rocks in a single well into eight phases and multi-well correlation under the constraint of seismic phases. (e.g.) Figure 9 , Figure 10 )

[0108] In summary, the content of this invention is not limited to the above-described embodiments. Those skilled in the art can easily propose other embodiments within the technical guiding principles of this invention, but such embodiments are all included within the scope of this invention.

Claims

1. A method for the phase division and multi-well comparative evaluation of volcanic rocks combining well and seismic analysis, characterized in that, Includes the following steps: A. Identifying the developmental sections of volcanic rocks in a single well A1. Collect basic data on volcanic rocks Collect core observation data, cuttings logging data, well logging curve data, and 3D seismic data from cored wells; among which, well logging curve data includes natural gamma ray logging curves, neutron logging curves, sonic transit time logging curves, density logging curves, and bottom 2.5m gradient resistivity logging curves. Natural gamma ray logging curves are abbreviated as GR curves, neutron logging curves as CN curves, sonic transit time logging curves as AC curves, and density logging curves as DEN curves. A2. Identifying volcanic rock development zones Observe the core samples from the core wells to identify the volcanic rock and mudstone development zones; standardize the AC, GR, DEN, and CN curves of the volcanic rock and mudstone, and establish a well logging curve cross-plot with the AC curve as the abscissa and the GR, CN, and DEN curves as the ordinates respectively. From the cross-plot, obtain the identification criteria for the well logging curves of the volcanic rock and mudstone, and perform lithological identification on the non-core sections and non-core wells according to the identification criteria. B. Creating single-well synthetic seismic records B1. Analyze the seismic spectrum of volcanic rock formations and generate seismic wavelets. Extract the spectral curves of seismic records from volcanic rock strata, analyze the dominant frequency of the volcanic rock seismic data based on the spectral curves, and extract the Ricker wavelet W(t) of the dominant frequency as the seismic wavelet: W(t) = exp(-(2π x fm x t) x cos(2 x π x fm x t) 2 ) x cos(2 x π x fm x t) In the formula, t represents time; fm is the main frequency B2. Production of single-well synthetic seismic records The reflection coefficient R(t) of a single well is calculated using the acoustic transit time and the compensated density logging curve, and the seismic wavelet W(t) is convolved to produce a single-well synthetic seismic record F(t). F(t) = R(t) × W(t) In the formula, F(t) represents the seismic record; W(t) represents the seismic wavelet; and R(t) represents the reflection coefficient. R i = (Z i - Z i-1 ) / (Z i + Z i-1 ) With i =in i ×ρ i In the formula, R i Z is the reflection coefficient at depth i; i Acoustic impedance at depth of layer i; v i Let ρ be the acoustic time difference at depth i; i H represents the depth compensation density of the i-th layer; i Let i be the depth of the i-th layer; C. Determine the seismic response characteristics within the volcanic rock mass and characterize the phased distribution of earthquake magnitudes. C1. Seismic tracking of the top and bottom interfaces and outer contours of volcanic rock masses. Using the results of single-well synthetic records, the seismic response intervals at the top and bottom of the volcanic rock were identified, and the amplitude response characteristics of the volcanic rock mass and the overlying and underlying sedimentary rocks were obtained. Combined with the seismic amplitude variation characteristics, the external contour of the volcanic rock mass in the three-dimensional seismic body was characterized. C2. Identifying the internal structure of volcanic rock masses Guided by the seismic response characteristics of the chaotic reflection volcanic conduit phase, the medium-to-weak amplitude volcanic eruption phase, and the strong amplitude medium-to-high continuity volcanic overflow phase, the internal structural characteristics of the volcanic rock mass are identified. Based on the different frequencies of earthquakes along the same direction axis, the earthquake magnitude within the volcanic rock mass is determined as the sequence. D. Classification of single-well volcanic rock periods under the constraint of seismic periods D1. The sediments from the intervolcanic period are mudstone, and mudstone is used as the boundary for dividing the volcanic rock phases in a single well; D2. Using mudstone interlayers as the dividing interface, complete the single-well volcanic rock period division and multi-well comparison under the constraint of seismic period.

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