Method of seismic attribute generation and seismic exploration

A seismic map for use in geophysical exploration prepared by a process, comprising the steps of:

• (a) accessing, by means of a computer, a data set comprising seismic traces distributed over a pre-determined volume of the earth;
• (b) selecting a target seismic trace having a surface location and at least two other seismic traces having surface locations from said set of seismic traces;
• (c) calculating a complex similarity matrix from said selected seismic traces;
• (d) calculating a seismic attribute from said complex similarity matrix;
• (e) storing said seismic attribute at a position representative of the surface location of the target trace;
• and,
• (f) repeating steps (b) through (e) for at least two additional target traces, thereby creating a stored plane of seismic attributes;
• and,
• (g) converting said stored plane of seismic attributes into a printed display for use in the identification and detection of subsurface features that are conducive to hydrocarbon formation, migration, or occurrence.

In a digital computer wherein a data set of spatially related seismic traces obtained over a pre-determined volume of the earth are read into memory, wherein said spatially related seismic traces contain signals representative of at least a portion of said volume, and wherein said digital computer is used to form an attribute display for use in seismic exploration, a digital computer programmed to perform a process comprising the steps of:

• (a) selecting at least three seismic traces from said spatially related seismic traces, each of said selected seismic traces being characterized by at least a surface location;
• (b) calculating a complex similarity matrix from said selected seismic traces;
• (c) calculating a seismic attribute from said complex similarity matrix;
• (d) storing said seismic attribute at a position representative of the surface location of one of said selected seismic traces;
• and,
• (e) repeating steps (a) through (d) for at least two additional target traces, thereby forming a stored attribute display which can be used to detect subsurface features that are conducive to hydrocarbon formation, migration, or occurrence.

A method of seismic attribute generation for use in geophysical exploration for hydrocarbons, wherein a reference frequency and a plurality of specified auxiliary frequencies have been provided, comprising the steps of:

• (a) obtaining a set of spatially related seismic traces distributed over a 3-D volume of the earth, said spatially related seismic traces containing signals representative of at least a portion of said volume, and each spatially related seismic trace in said set being associated with a surface location;
• (b) selecting a target seismic trace and at least two other seismic traces from said set of seismic traces, said target trace having a surface location;
• (c) calculating a reference frequency complex similarity matrix at said reference frequency from said selected seismic traces;
• (d) choosing an auxiliary frequency from among said specified auxiliary frequencies;
• (e) calculating a single frequency phase-corrected complex similarity matrix at said chosen auxiliary frequency from said selected seismic traces;
• (f) performing steps (d) and (e) as required until a predetermined number of the specified auxiliary frequencies have been chosen;
• (g) combining any phase-corrected single frequency complex similarity matrices calculated in steps (e) and (f) with said reference frequency complex similarity matrix to form a composite complex similarity matrix;
• (h) calculating a seismic attribute from said composite complex similarity matrix;
• (i) storing said seismic attribute at a position representative of the surface location of said target trace;
• and,
• (j) repeating steps (b) through (i) for at least two other target traces, thereby creating a stored plane of seismic attributes which can be used to detect subsurface features that are conducive to hydrocarbon formation, migration, or occurrence.

In the exploration for hydrocarbons, a seismic attribute map for use by an explorationist in identifying potential drilling sites, wherein subsurface features associated with the migration, accumulation or presence of hydrocarbons have been accentuated, said map being prepared by a process, said process comprising the steps of:

• (a) accessing by means of a computer, a data set comprising spatially related seismic signal traces distributed over a pre-determined volume of the earth, said seismic signal traces being characterized by at least a surface location;
• (b) selecting a target location, said target location having at least three seismic signal traces proximate thereto;
• (c) selecting at least three seismic traces from said seismic signal traces proximate to said target location;
• (d) calculating a complex similarity matrix from said selected seismic traces;
• (e) calculating a seismic attribute from said complex similarity matrix;
• (f) storing said seismic attribute at a position representative of the surface location of one of the selected seismic traces;
• (g) repeating steps (b) through (f) for at least two additional target locations, thereby creating a stored plane of seismic attributes;
• and,
• (h) displaying said stored plane of seismic attributes on a generally flat medium for recording visually perceptible images thereon.

A method for the exploration of hydrocarbons, wherein a predetermined volume of the earth containing structural and stratigraphic features has been specified, comprising:

• (a) obtaining a representation of a set of spatially related seismic traces distributed over said pre-determined volume of the earth, said spatially related seismic traces containing signals representative of at least a portion of said structural and stratigraphic features, and each of said spatially related seismic traces being characterized by at least a location on a surface of the earth;
• (b) selecting a target location on the surface of the earth, said target location having at least three seismic traces proximate thereto;
• (c) selecting at least three traces from said at least three seismic traces proximate to said target location;
• (d) calculating a similarity matrix from said selected traces, said similarity matrix having a plurality of eigenvectors;
• (e) calculating a particular eigenvector of said similarity matrix, said particular eigenvector containing eigenvector elements;
• (f) associating each of said eigenvector elements with an eigenvector element surface location;
• (g) fitting a function characterized by constant coefficients to said eigenvector elements and said eigenvector element surface locations, thereby obtaining one or more constant coefficient estimates;
• (h) calculating a seismic attribute from any of said constant coefficient estimates so obtained;
• (i) storing said seismic attribute at a position representative of said target location;
• and,
• (j) repeating steps (b) through (i) for at least two additional target locations, thereby creating a stored plane of seismic attributes, said stored plane of seismic attributes being used to identify subsurface structural and stratigraphic features that are conducive to the migration, accumulation, or presence of hydrocarbons, conducive to the migration, accumulation, or presence of hydrocarbons.

A seismic map for use in geophysical exploration, said map prepared by a process comprising the steps of:

• (a) accessing, by means of a computer, a data set comprising seismic traces distributed over a pre-determined volume of the earth;
• (b) selecting a target seismic trace having a surface location and at least two other seismic traces having surface locations from said set of seismic traces;
• (c) calculating a similarity matrix from said selected seismic traces, said similarity matrix having a plurality of eigenvectors;
• (d) calculating a particular eigenvector of said similarity matrix, said particular eigenvector having eigenvector elements;
• (e) associating each of said eigenvector elements with a surface location;
• (f) fitting a function characterized by constant coefficients to said eigenvector elements and said surface locations, thereby obtaining one or more constant coefficient estimates;
• (g) calculating a seismic attribute from any of said constant coefficient estimates so obtained;
• (h) storing said seismic attribute at a position representative of the surface location of the target trace;
• and,
• (i) repeating steps (b) through (h) for at least two additional target traces, thereby creating a stored plane of seismic attributes;
• and,
• (j) converting said stored plane of seismic attributes into a printed display for use in the identification and detection of subsurface features that are conducive to hydrocarbon formation, migration, or occurrence.

In a digital computer wherein a data set of spatially related seismic traces obtained over a pre-determined volume of the earth are read into memory, and wherein said digital computer is used to form an attribute display for use in seismic exploration, a digital computer programmed to perform a process comprising the steps of:

• (a) selecting a target seismic trace and at least two other seismic signal traces from said spatially related seismic traces;
• (b) calculating a similarity matrix from said selected seismic traces, said similarity matrix having a plurality of eigenvectors;
• (c) calculating a particular eigenvector of said similarity matrix, said eigenvector consisting of eigenvector elements;
• (d) associating with each of said eigenvector elements a location;
• (e) fitting a function characterized by constant coefficients to said eigenvector elements and said locations, thereby obtaining one or more constant coefficient estimates;
• (f) calculating a seismic attribute from any of said constant coefficient estimates so obtained;
• (g) storing said seismic attribute at a position representative of the surface location of the target trace;
• and,
• (h) repeating steps (b) through (g) for at least two additional target traces, thereby creating a stored attribute display, said stored attribute display being used to identify subsurface structural and stratigraphic features that are conducive to the migration, accumulation, or presence of hydrocarbons.

In the exploration for hydrocarbons, a seismic attribute map for use by an explorationist in identifying subsurface features associated with the migration, accumulation or presence of hydrocarbons, said map being prepared by a process, said process comprising the steps of:

• (a) accessing by means of a computer, a data set comprising spatially related seismic traces distributed over a pre-determined volume of the earth, said seismic traces containing digital information representative of subterranean structures and stratigraphy;
• (b) selecting at least three seismic traces from said data set of spatially related seismic traces, said selected seismic traces each being characterized by at least a surface location;
• (c) calculating a similarity matrix from said selected seismic traces, said similarity matrix having a plurality of eigenvectors;
• (d) calculating a particular eigenvector of said similarity matrix, said eigenvector being characterized by a plurality of eigenvector elements;
• (e) associating a surface location with each of said plurality of eigenvector elements;
• (f) selecting a function characterized by at least one constant coefficient;
• (g) fitting said function to said plurality of eigenvector elements and surface locations, thereby producing at least one constant coefficient estimate;
• (h) calculating a seismic attribute from any of said constant coefficient estimates so produced;
• (i) storing said seismic attribute at a position representative of the surface location of one of said selected seismic traces;
• (j) repeating steps (b) through (i) for at least two additional target traces, thereby creating a stored plane of seismic attributes;
• and,
• (k) displaying said plane of seismic attributes on a generally flat medium for recording visually perceptible images thereon.

A method of geophysical exploration, wherein unstacked seismic traces are analyzed for variations in seismic reflector amplitude with changing offset distance from a CMP location, said method comprising the steps of:

• (a) obtaining a representation of an unstacked seismic data set, said unstacked seismic data set being organized into a plurality of CMP gathers, each of said CMP gathers being associated with a location on the surface of the earth and each of said CMP gathers consisting of at least one unstacked seismic trace;
• (b) selecting a CMP gather consisting of at least three unstacked seismic traces from said plurality of CMP gathers;
• (c) selecting at least three traces from said unstacked seismic traces in said selected CMP gather, each of said selected traces being associated with a location on the surface of the earth;
• (d) calculating a similarity matrix from said selected traces, said similarity matrix having a plurality of eigenvectors;
• (e) calculating a particular eigenvector of said similarity matrix, said particular eigenvector having eigenvector elements;
• (e) associating each of said eigenvector elements with a surface location;
• (f) fitting a function characterized by constant coefficients to said eigenvector elements and said surface locations, thereby obtaining one or more constant coefficient estimates;
• (g) calculating a seismic attribute from any of said constant coefficient estimates so obtained;
• (h) storing said seismic attribute at a position representative of said surface location of said selected CMP gather;
• and,
• (i) repeating steps (b) through (h) for at least two additional CMP gathers, thereby creating a stored plane of seismic attributes, said stored plane of seismic attributes being used to identify amplitude variations with offset that are indicative of subsurface features conducive to the accumulation or presence of hydrocarbons.

A method for the exploration of hydrocarbons, wherein unstacked seismic traces containing subsurface structural and stratigraphic information are analyzed for AVO effects, comprising the steps of:

• (a) obtaining a representation of an unstacked seismic data set, said unstacked seismic data set being organized into a plurality of CMP gathers, each of said CMP gathers being associated with a location on the surface of the earth and each of said CMP gathers consisting of at least one unstacked seismic trace;
• (b) selecting a CMP gather consisting of at least three unstacked seismic traces from said plurality of CMP gathers;
• (c) selecting at least three traces from said unstacked seismic traces in said selected CMP gather, each of said selected traces being associated with a location on the surface of the earth;
• (d) calculating a complex similarity matrix from said selected traces;
• (e) calculating a seismic attribute from said complex similarity matrix;
• (f) storing said seismic attribute at a position representative of said surface location of said selected CMP gather;
• and,
• (g) repeating steps (b) through (f) for at least two additional CMP gathers, thereby creating a stored plane of seismic attributes, said stored plane of seismic attributes being used to identify amplitude variations with offset that are indicative of subsurface features conducive to the accumulation or presence of hydrocarbons.

A method for the exploration of hydrocarbons, comprising:

• (a) obtaining a set of spatially related seismic traces distributed over a surface of the earth, said seismic traces containing signals representative of subterranean structures and stratigraphy;
• (b) selecting a target seismic trace having a surface location and at least two other seismic traces having surface locations from said set of seismic traces;
• (c) calculating a complex similarity matrix from said selected seismic traces;
• (d) calculating a seismic attribute from said complex similarity matrix;
• (e) storing said seismic attribute at a position representative of the surface location of the target trace;
• and,
• (f) repeating steps (b) through (e) for at least two additional target traces, thereby creating a stored plane of seismic attributes, said stored plane of seismic attributes being used to identify subsurface structural and stratigraphic features that are conducive to the migration, accumulation, or presence of hydrocarbons.

A method of geophysical exploration, comprising the steps of:

• (a) obtaining a set of spatially related seismic traces distributed over a surface of the earth, said seismic traces containing signals representative of subterranean structures and stratigraphy;
• (b) selecting a target seismic trace and at least two additional neighborhood seismic traces from said spatially related, said selected seismic traces being characterized by at least a surface location;
• (c) calculating a similarity matrix from said selected seismic traces, said similarity matrix having a plurality of eigenvectors;
• (d) calculating a particular eigenvector of said similarity matrix, said particular eigenvector containing eigenvector elements;
• (e) associating each of said eigenvector elements with a surface location;
• (f) fitting a function characterized by constant coefficients to said eigenvector elements and said surface locations, thereby obtaining one or more constant coefficient estimates;
• (g) calculating a seismic attribute from any of said constant coefficient estimates so obtained;
• (h) storing said seismic attribute at a position representative of the surface location of the target trace;
• and,
• (i) repeating steps (b) through (h) for at least two additional target traces, thereby creating a stored plane of seismic attributes, said stored plane of seismic attributes being used to identify subsurface structural and stratigraphic features that are conducive to the migration, accumulation, or presence of hydrocarbons.