Seismic data recording and processing with different uncontaminated recording time lengths

A computing device for generating an image of a subsurface based on blended seismic data, the computing device comprising:

• an interface configured to receive the blended seismic data, which is recorded so that plural traces have uncontaminated parts with different uncontaminated recoding time lengths;
• and
• a processor coupled to the interface and configured to,
• select plural subgroups (SG1, SG2) of traces so that each subgroup (SG1) includes only uncontaminated parts that have a same uncontaminated recording time length,
• independently process the traces from each subgroup to generate processed traces,
• map the processed traces to a same sampling,
• combine the processed traces from the plural subgroups (SG1, SG2) to generate combined processed traces, and
• generate an image of a structure of the subsurface based on the combined processed traces.

A method for acquiring blended seismic data of a subsurface, the method comprising:

• towing first and second seismic sources S1, S2 above the subsurface;
• firing the first and second seismic sources S1, S2 with corresponding first and second lags, L1 and L2, respectively, relative to pre-determined shotpoints, wherein the first lag L1 is different from the second lag L2;
• and
• recording blended seismic data corresponding to the shooting of the first and second seismic sources S1, S2,
• wherein the blended seismic data includes plural traces having cross-talk free parts with different uncontaminated recording time lengths.