Depth imaging of reservoirs using well logs, VSP and surface seismic data

Abstract

One broad objective of geophysics is to produce subsurface images which represent geology as accurately as possible. The goal in this paper is to construct pictures of lithology in depth. An overview of a tomographic method (traveltime inversion) is presented here which uses well-logs, VSP and surface seismic data to produce a velocity structure in depth. This velocity structure is then used in the surface seismic inversion process and depth migration. Thus, the described processing flow attempts to provide accurate stratigraphic and structural depth pictures. Two examples of oil field development plays in Alberta are processed in the above manner. A brief discussion of the geology, data acquired and interpreted results is presented here. It is found that tomography-based imaging can provide seismic depth sections which are consistent with well-logs in the regions under consideration. Previous attempts to tie the seismic sections into depth, without VSP and tomographic analysis, had proved inaccurate. Depth sections and tomography-constrained, pseudo-sonic sections assist in the structural and stratigraphic interpretation of the reservoirs in the two cases.