Reservoir Description Using 3-D Seismic Data

CURTIS, MICHAEL P., Halliburton Geophysical Services, Inc., Sugar Land, TX

During the past decade three-dimensional (3-D) seismic surface reflection data have become increasingly accepted and routinely integrated with well and production data. This integration has lead to more detailed descriptions of reservoir geometries and volumes. Most recently, 3-D seismic has been used to map spatial changes in both lithology and fluid fractions obtained form core data and from well log inversion.

Data may be collected and processed in several ways depending on location (land or marine), depth, and attitude of target, resolution required, and, of course, budget available. The three most widely used methods are detailed 3-D in land and marine, exploration 3-D (mostly marine), and super 2-D for smaller land areas where budgets or access is limited. The process of 3-D seismic data migration correctly images the seismic events spatially.

3-D data are superior to their 2-D counterparts because the method samples the subsurface very densely. As a result, the problem of spatial aliasing during mapping is removed and resulting interpretations are structurally, stratigraphically, and petrophysically highly detailed.

Depositional features such as channels and reefs frequently are seen on horizontal slices taken through 3-D data volumes. The close spatial sampling of the data allows us to look at vertical profiles in any direction through the field, such as strike, dip, or random lines that may link existing well control.

Faults may be more easily mapped and subtle splinter and bifurcation patterns can be resolved that support more detailed reservoir models. The improved definition of structure that 3-D seismic provides improves our understanding of growth, erosional history, and fracture orientation for more effective horizontal well placement, engineering studies, and recovery.

When the acoustic properties of reservoir zones are satisfactory, fluid contacts may be seen and contact mapping may then lead to better volumetric computations. An exciting new application of 3-D seismic is in the monitoring of these contacts and flood fronts during production and enhanced oil recovery projects. This monitoring is achieved by the interpretation of multiple surveys collected as production progresses.

AAPG Search and Discovery Article #91011©1991 AAPG Southwest Section Meeting, Abilene, Texas, February 9-12, 1991 (2009)