Apparatus and method for mapping lateral variation of subsurface impedance
AssigneeSaudi Arabian Oil Company
InventorMohammad H. Al-Fares
Life of this patent
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Abstract
A technique for mapping lateral impedance of a subsurface layer is disclosed. Amplitudes are selected along a lateral slice of seismic data and an impedance model that generates values which approximate the selected amplitudes is developed. The lateral impedance of the subsurface layer is determined from the model and is mapped laterally, to produce a visual representation of the lateral impedance.
Claims37
A method for mapping lateral impedance of a subsurface layer comprising the steps of:
- generating seismic data,
- picking amplitudes along a lateral slice of the seismic data,
- developing an impedance model that generates values which approximate said picked amplitudes,
- determining lateral impedance of the subsurface layer from the model,
- mapping the lateral impedance of the subsurface layer, and
- producing a visual representation of said lateral impedance.
A method for mapping lateral impedance of an unknown subsurface layer comprising the steps of:
- determining lateral background impedance I.sub.0 (x) from known impedance data,
- determining the lateral impedance I.sub.1 (x) of a previous subsurface layer above or below the unknown subsurface layer,
- calculating lateral background reflectivity r.sub.o (x) based on the lateral background impedance I.sub.0 (x) and the lateral impedance I.sub.1 (x) of the previous subsurface layer,
- generating seismic data,
- picking amplitudes along a lateral slice of the seismic data,
- taking the difference between the picked amplitudes and the lateral background reflectivity to form lateral difference reflectivity data, .DELTA.r(x),
- developing an impedance model that generates values which approximate said lateral difference reflectivity data,
- determining lateral difference impedance .DELTA.I(x) from the impedance model,
- adding the lateral difference impedance to the lateral background impedance to determine lateral impedance of the unknown layer,
- mapping the lateral impedance of the unknown layer, and
- producing a visual representation of said lateral impedance.
An apparatus for mapping lateral impedance of an unknown subsurface layer comprising:
- means for generating seismic data,
- means for selecting amplitudes along a lateral slice of the seismic data,
- means for developing an impedance model that generates values which approximate said selected amplitudes,
- means for determining lateral impedance of a subsurface layer from the model,
- means for mapping the lateral impedance, and
- means for producing a visual representation of said lateral impedance.
An apparatus for mapping lateral impedance of an unknown subsurface layer comprising:
- signal generating means for generating and directing signals into subsurface layers,
- signal receiving means for receiving signals in the form of seismic data reflected back from the interfaces of subsurface layers,
- means for generating impedance data at a plurality of spaced well locations,
- processing means for determining lateral background impedance I.sub.0 (x) from the impedance data from the plurality of spaced well locations,
- processing means for determining an estimate of the lateral impedance I.sub.1 (x) of the subsurface layer vertically adjacent the unknown subsurface layer,
- means for determining lateral background reflectivity r.sub.0 (x) from the lateral background impedance I.sub.0 (x) and the lateral impedance I.sub.1 (x) of the subsurface layer vertically adjacent the unknown subsurface layer,
- means for determining the difference between amplitudes selected along a lateral slice of the seismic data and the lateral background reflectivity to form lateral difference reflectivity data, .DELTA.r(x),
- means for developing an impedance model that generates values which approximate said lateral difference reflectivity data,
- means for determining the lateral impedance from said impedance model,
- mapping means for mapping the lateral impedance of the unknown subsurface layer, and
- means for producing a visual representation of said lateral impedance.
Dependencies are inferred from the claim text.