Abstract A number of seismic detectors are located in a two-dimensional array on the surface of the earth, either on land or at sea. One or more seismic disturbances are produced in the vicinity of the seismic detectors at points located to produce sampling of various subsurface reflection points to form one or more two-dimensional areas of coverage. For each seismic disturbance, the subsurface reflections thereof received by the various seismic detectors are recorded. In some embodiments, the seismic disturbances are produced at points located to produce multi-directional or multi-azimuth sampling of each of various subsurface reflection points and recordings for different ones of the seismic disturbances are combined to produce stacked recordings wherein multi-directional reflections from common subsurface points are added. By sampling a reflecting point in a multi-directional manner and stacking the recorded samples, diffraction barriers can be effectively penetrated to produce a discernable signal representing the reflecting point notwithstanding the diffraction barrier. Multi-directional or multi-azimuth sampling of reflecting points can be employed to survey beneath surface features such as inhabited areas or seismically opaque features such as salt pockets by utilizing source points and detecting points located away from and on opposite sides of the blocking feature.
A method for penetrating a seismic diffraction barrier created by objects in, in the neighborhood of, or above a geologic region of interest desired to be seismically explored comprising: generating multiple pieces of data from a given reflecting point by means of disturbances created at source points and detectors located at detecting points such that at least some pairs, each pair comprising one source point and one detecting point, are aligned on azimuths which intersect at a vertical line passing through said reflecting point; recording said multiple pieces of data, said data recordings containing diffraction signals masking a signal from said reflecting point in the geologic region of interest; and combining data recordings containing data generated along a multiplicity of azimuths having a common intersection, whereby said diffraction signals in large part additively cancel one another and the signals from said reflecting point additively reinforce one another, to produce a composite recording containing a discernable signal representing said reflecting point.
Claim 2
Independent Claim
160 words
A method for penetrating a seismic diffraction barrier created by objects in, in the neighborhood of, or above a geologic region of interest desired to be seismically explored comprising: generating multiple pieces of data from a given reflecting point by means of disturbances created at source points and detectors located at detecting points such that at least some pairs, each pair comprising one source point and one detecting point, are aligned on azimuths which intersect at a vertical line passing through said reflecting point; recording said multiple pieces of data, said data recordings containing diffraction signals masking a signal from said reflecting point in the geologic region of interest; and combining data recordings containing data generated along a multiplicity of azimuths having a common intersection, whereby said diffraction signals in large part additively cancel one another and the signals from said reflecting point additively reinforce one another, to produce a composite recording containing a discernable signal representing said reflecting point.
Claim 3
Independent Claim
155 words
A method for seismically exploring a geologic region of interest so located with respect to a surface or subsurface feature above it that substantially no meaningful seismic data can be obtained by running a survey line across said feature and the region of interest, said method comprising; developing multiple pieces of data from a given reflecting point in said geologic region of interest from a multiplicity of pairs of seismic disturbance source points and detector points, ssaid pairs being aligned on azimuths which intersect at a vertical line passing through said reflecting point and said source points and detector points being located on the surface in areas away from said feature, the source point of any given pair being positioned on the opposite side of said feature from the detecting point of said pair; recording the multiple pieces of data so developed; and stacking recordings of data from said reflecting point generated along intersecting azimuths.
Claim 4
Independent Claim
155 words
A method for seismically exploring a geologic region of interest so located with respect to a surface or subsurface feature above it that substantially no meaningful seismic data can be obtained by running a survey line across said feature and the region of interest, said method comprising; developing multiple pieces of data from a given reflecting point in said geologic region of interest from a multiplicity of pairs of seismic disturbance source points and detector points, ssaid pairs being aligned on azimuths which intersect at a vertical line passing through said reflecting point and said source points and detector points being located on the surface in areas away from said feature, the source point of any given pair being positioned on the opposite side of said feature from the detecting point of said pair; recording the multiple pieces of data so developed; and stacking recordings of data from said reflecting point generated along intersecting azimuths.