US4692910A
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Methods of determining lithological characteristics of an underground formation which utilize compressional velocity and shear velocity data
Assignee: BP Corp North America Inc
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Filing: 1985-03-11
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Granted: 1987-09-08
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Expires: 2005-03-11
Abstract
Abstract Methods and related apparatus are described for determining lithological characteristics, such as formation material type and porosity, of an underground formation by utilizing compressional velocity (V p ) and shear velocity (V s ) data. One described method utilizes the plotting of V p and/or V s versus a Seismic Parameter, such ad K/ρ or the Bulk Velocity, and boundaries of velocity values of certain formation material types to define a field of data points. By comparing the position of the data points to the boundaries of the formation material types, the formation material type and, later, porosity can be determined. A method is described for determining the presence of a hydrocarbon gas at a particular location in an underground formation utilizing the above methods. Also, a method is described for determining V s from V p data and obtained ratios of V p and V s for at least one formation material type.
Inventors
- 👤 Carl H. Sondergeld
- 👤 Albert L. Frisillo
- 👤 Janice O. Norris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:27
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/28; G01V1/284; G01V1/30; G01V1/303
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
A method of determining the formation material type at a particular location in an underground formation by utilizing compressional velocity data (V p ) and shear velocity data (V s ), comprising: (a) calculating bulk velocity (V B ) utilizing V p and V s data wherein ##EQU2## (b) plotting V B on one axis and V p on a second axis to define a field of data points, wherein each data point corresponds to a particular location in the underground formation; (c) including velocity boundaries of V B and V p within the plot of (b) for at least one formation material type; and (d) determining from the position of a data point relative to the velocity boundaries, the formation material type.
Claim 2
Independent Claim
123 words
A method of determining the formation material type at a particular location in an underground formation by utilizing compressional velocity data (V p ) and shear velocity data (V s ), comprising: (a) calculating bulk velocity (V B ) utilizing V p and V s data wherein ##EQU2## (b) plotting V B on one axis and V p on a second axis to define a field of data points, wherein each data point corresponds to a particular location in the underground formation; (c) including velocity boundaries of V B and V p within the plot of (b) for at least one formation material type; and (d) determining from the position of a data point relative to the velocity boundaries, the formation material type.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the velocity boundaries are determined in (c) for carbonates, sandstones, and shales.
Claim 4
Independent Claim
223 words
A method of determining the porosity of an underground formation by utilizing compressional velocity (V p ) and shear velocity data (V s ), comprising: (a) calculating bulk velocity (V B ) utilizing V p and V s data wherein ##EQU3## (b) plotting V B on one axis and (V p , V s or 1/V s ) on a second axis to define a field of data points, wherein each data point corresponds to a particular location within the underground formation; (c) including velocity boundaries of V B and (V p , V s or 1/V s ) within the plot of (b) for at least one formation material type; (d) determining from the position of the data points relative to the velocity boundaries the formation material types; (e) including on a third axis in the plot of (b), porosity boundaries for the formation material types to define a three-dimensional field of data points; (f) fitting to the three-dimensional field of data points of (e) a mathematical surface defined as φ=K 1 (V p , V s or 1/V s )+K 2 V B +K 3 , where K 1 , K 2 and K 3 are fitted constants; and (g) utilizing the V p and V s data, solving the equation of (f) to determine the porosity of the underground formation.
Claim 5
Independent Claim
223 words
A method of determining the porosity of an underground formation by utilizing compressional velocity (V p ) and shear velocity data (V s ), comprising: (a) calculating bulk velocity (V B ) utilizing V p and V s data wherein ##EQU3## (b) plotting V B on one axis and (V p , V s or 1/V s ) on a second axis to define a field of data points, wherein each data point corresponds to a particular location within the underground formation; (c) including velocity boundaries of V B and (V p , V s or 1/V s ) within the plot of (b) for at least one formation material type; (d) determining from the position of the data points relative to the velocity boundaries the formation material types; (e) including on a third axis in the plot of (b), porosity boundaries for the formation material types to define a three-dimensional field of data points; (f) fitting to the three-dimensional field of data points of (e) a mathematical surface defined as φ=K 1 (V p , V s or 1/V s )+K 2 V B +K 3 , where K 1 , K 2 and K 3 are fitted constants; and (g) utilizing the V p and V s data, solving the equation of (f) to determine the porosity of the underground formation.
Claim 6
Independent Claim
145 words
A method of determining the presence of a gaseous hydrocarbon at a particular location in an underground formation by utilizing compressional velocity data (V p ) and shear velocity data (V s ), comprising: (a) determining a first series of porosity values utilizing the equation Porosity φ=K 1 (V p /V s )+K 2 V s +K 3 , where K 1 , K 2 and K 3 are fitted constants; (b) determining a second series of porosity values utilizing the equation Porosity (φ)=K 4 bulk velocity V B +K 5 V p +K 6 where K 4 , K 5 and K 6 are fitted constants and ##EQU4## (c) determining at which location in an underground formation a value of porosity from (a) is equal to or less than a corresponding value of porosity from (b) thereby indicating the presence of a gaseous hydrocarbon.
Claim 7
Independent Claim
145 words
A method of determining the presence of a gaseous hydrocarbon at a particular location in an underground formation by utilizing compressional velocity data (V p ) and shear velocity data (V s ), comprising: (a) determining a first series of porosity values utilizing the equation Porosity φ=K 1 (V p /V s )+K 2 V s +K 3 , where K 1 , K 2 and K 3 are fitted constants; (b) determining a second series of porosity values utilizing the equation Porosity (φ)=K 4 bulk velocity V B +K 5 V p +K 6 where K 4 , K 5 and K 6 are fitted constants and ##EQU4## (c) determining at which location in an underground formation a value of porosity from (a) is equal to or less than a corresponding value of porosity from (b) thereby indicating the presence of a gaseous hydrocarbon.
Claim 8
Dependent Claim
22 words
The method of claim 4 wherein step (c) includes utilizing parallel line plots of the first and second series of porosity values.
Claim 9
Dependent Claim
198 words
The method of claim 4 wherein step (a) comprises: (a) plotting V p /V s on one axis and (V p , V s , or 1/V s ) on a second axis to define a field of data points, wherein each data point corresponds to a particular location within the underground formation; (b) including velocity boundaries of V p /V s and (V p , V s or 1/V s ) within the plot of (a) for at least one formation material type; (c) determining from the position of the data points relative to the velocity boundaries the formation material types; (d) including on a third axis in the plot of (a), porosity boundaries for the formation material types to define a three-dimensional field of data points; (e) fitting to the three-dimensional field of data points of (d) a mathematical surface defined as Porosity (φ)=K 1 (V p , V s , or 1/V s ) +K 2 (V p /V s )+K 3 , where K 1 , K 2 , and K 3 are fitted constants; and (f) utilizing the V p and V s data, solving the equation in (e) to determine the porosity.
Claim 10
Dependent Claim
189 words
The method of claim 4 wherein (e) comprises: (a) plotting S on one axis and (V p , V s or 1/V s ) on a second axis to define a field of data points, wherein each data point corresponds to a particular location within the underground formation; (b) including velocity boundaries of V B and (V p , V s , or 1/V s ) within the plot of (a) for at least one formation material type; (c) determining from the position of the data points relative to the velocity boundaries the formation material types; (d) including on a third axis in the plot of (a), porosity boundaries for the formation material types to define a three-dimensional field of data points; (e) fitting to the three-dimensional field of data points of (d) a mathematical surface defined as Porosity (φ)=K 1 (V p , V s , or 1/V s )+K 2 V B +K 3 , where K 1 , K 2 , and K 3 are fitted constants; and (f) utilizing the V p and V s data, solving the equation in (e) to determine the porosity.
Claim 11
Independent Claim
110 words
A method of determining shear velosity (V s ) comprising: (a) determining the ratios of V p and V s for at least one formation material; (b) plotting V s on one axis and V p on a second axis for at least two samples of at least one formation material type to define a field of data points; (c) fitting an equation: V s =K 1 (V p )+K 2 V p 2 +K 3 to the field of data points, where K 1 , K 2 and K 3 are fittend constants; and (d) utilizing the V p data, solving the equation in (c) for V s .
Claim 12
Independent Claim
110 words
A method of determining shear velosity (V s ) comprising: (a) determining the ratios of V p and V s for at least one formation material; (b) plotting V s on one axis and V p on a second axis for at least two samples of at least one formation material type to define a field of data points; (c) fitting an equation: V s =K 1 (V p )+K 2 V p 2 +K 3 to the field of data points, where K 1 , K 2 and K 3 are fittend constants; and (d) utilizing the V p data, solving the equation in (c) for V s .
References Cited (Backward Citations)
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Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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