Localized full waveform inversion using synthetic energy focusing

A computer-implemented method of Full Waveform Inversion for estimating at least one subsurface property using seismic survey data collected from an array of seismic sources and receivers, employing the simulation of at least one convergent seismic source that focuses the seismic energy intensity (i.e. Convergent Focused Macro Source) towards a specific zone of the surveyed earth volume, comprising:

• a) defining a prior configuration of the at least one subsurface property, a prior configuration of the seismic velocity field, a target zone of the earth medium and at least one focus point within that zone;
• b) using the prior seismic velocity field to calculate travel times from the at least one focus point to each of the sources in the seismic survey array;
• c) using the calculated travel times to construct at least one convergent seismic focused macro source (CFMS) for each focus point, wherein the total number of constructed FMSs is a fraction of the total number of seismic sources in the survey array, resulting in savings in the computational cost of the full waveform inversion proportional to that fraction;
• d) using the superposition principle, calculated travel times, and recorded seismic data to generate, for each CFMS, a corresponding seismic CFMS observed gather that concentrates the seismic energy intensity towards the target zone, thereby producing a maximal data sensitivity within the target zone;
• e) numerically simulating the CFMS calculated gather corresponding to each of the CFMSs;
• f) utilizing both the CFMS observed gathers and the corresponding CFMS calculated gathers in a Full Waveform Inversion method to estimate the said at least one subsurface property within the target zone, thereby reducing computational cos;
• and
• g) employing the estimated at least one subsurface property to characterize the subsurface formations, explore the presence of natural resources, and/or assist in the extraction or injection of fluids into the subsurface formations;
• wherein the at least one subsurface property forms an image describing the earth medium sub-volume where seismic intensity was concentrated by the CFMSs.

A computer-implemented method of Full Waveform Inversion for estimating at least one subsurface property field using seismic survey data collected from an array of seismic sources and receivers, employing the simulation of at least two seismic beams that focuses the seismic energy intensity (i.e. Beam Focused Macro Sources) towards a specific zone of the surveyed earth volume, comprising:

• a) defining a prior configuration of the at least one subsurface property, a prior configuration of the seismic velocity field, a target zone of the earth medium and at least one focus point within that zone;
• b) using the prior seismic velocity field to calculate travel times from the at least one focus point to each of the sources in the seismic survey array;
• c) using the calculated travel times to construct at least two multi-point beam seismic focused macro sources BFMSs) for each focus point, wherein the total number of constructed BFMSs is a fraction of the total number of seismic sources in the survey array, resulting in savings in the computational cost of the full waveform inversion proportional to that fraction;
• d) using the superposition principle, calculated travel times, and recorded seismic data to generate, for each BFMS, a corresponding seismic BFMS observed gather that concentrates the seismic energy intensity towards the target zone, thereby producing a maximal data sensitivity within the target zone;
• e) numerically simulating the BFMSs calculated gather corresponding to each of the BFMSs;
• f) utilizing both the BFMS observed gathers and the corresponding BFMS calculated gathers in a Full Waveform Inversion method to estimate the said at least one subsurface property within the target zone, thereby reducing computational cost;
• and
• g) employing the estimated at least one subsurface property to characterize the subsurface formations, explore the presence of natural resources, and/or assist in the extraction or injection of fluids into the subsurface formations;
• wherein the at least one subsurface property forms an image describing the earth medium sub-volume where seismic intensity was concentrated by the BFMSs.