30 first look at subsurface near oset gather combinaon

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Unformatted text preview: noise reduc(on and minimum signal loss** Noise Reduc(on: Broadband Filter Low ­pass Comparisons 3/24/2006 Lindsay Lowe and Hunter Danque 26 Noise Reduc(on: Broadband Filter High ­pass comparisons 3/24/2006 Lindsay Lowe and Hunter Danque 27 Noise Reduc(on: Broadband Filter F1 = 30 F2= 45 F3 = 175 F4 = 225 3/24/2006 Lindsay Lowe and Hunter Danque 28 Noise Reduc(on: Trace Edi(ng Trace edi(ng removes bad shots or channels caused by equipment malfunc(ons or glitches in the field 3/24/2006 Lindsay Lowe and Hunter Danque 29 Noise Reduc(on: Trace Edi(ng 3/24/2006 Lindsay Lowe and Hunter Danque 30 First Look at Subsurface Near Offset Gather: Combina(on of all shots recorded at Channel 120 3/24/2006 Lindsay Lowe and Hunter Danque 31 Stacking: Geometry and CMP Sort •  Data acquisi(on and all previous processing steps are performed with the data in shot ­ receiver coordinates •  Further data processing steps are performed in common midpoint (CMP) ­offset coordinates Stacking: CMP Sort •  Just as the demul(plex performed in the field reorganized the data into common shot gathers, the CMP sort reorganizes the data into CMP gathers Stacking: CMP Sort CMP gathers are described in terms of fold, which is a measure of the number of data points available for each CMP. CMP sor(ng is a form of stacking, or adding, data in which signals add construc(vely, while random noise adds destruc(vely. Common Midpoint Spacing = 12.5 meters 3/24/2006 Lindsay Lowe and Hunter Danque 34 CMP Sort: Gain Recovery Essen(ally, you mul(ply all the amplitudes by a factor t2 to scale the amplitudes appropriately as seen above. Spherical Divergence Factor: t2 This step accounts for the fact that the seismic energy spreads out spherically as a func(on of (me squared. For every (me value, the same amount of energy is distributed over an ever increasingly large sphere. You apply gain recovery for spherical divergence (geometric spreading) to account for this. Stacking: Brutestack •  Sor(ng the data into CMPs is essen(al for velocity picking, stacking and migra(on later in the processing sequence. At this point, however,...
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