Abstract: Cross Well Seismic Reservoir Characterization

Hans Eric Sheline

A striking example of how Cross Well Seismic reflection data can help characterize a reservoir, has resulted from an ongoing Multi- Discipline study of the carbonate Mishrif reservoir offshore Dubai, U.A.E. Because the study objectives include a more detailed description of intra reservoir structure and layering, Dubai Petroleum Company (DPC) analyzed the feasibility of Cross Well Seismic (CWS) and decided to acquire two surveys between three wells 337 to 523 feet apart. DPC has concluded that CWS can be cost effectively acquired offshore, in a Carbonate reservoir; as well as processed and interpreted. However, generally it is not often easy to acquire cross well seismic when and where it will be most useful. A CWS survey can provide multiple images such as a velocity Tom gram, P-wave reflections, and S-wave reflections. To date, Tomograms and P-wave reflections have been produced, and the reflection data has proven to be the most useful for reservoir characterization.

Cross Well Seismic Reflection data have provided a level of vertical seismic reflection resolution of around 2 feet, which is more than 10 times better than surface seismic data (2D or 3D). The increase in vertical resolution has provided important detailed information about the reservoir, it's continuity/heterogeneity; it's detailed structure, stratigraphy and layering; and definition of any faults with more than 2 feet of offset. The CWS has shown detailed intra Mishrif reflectors. These reflectors have verified or changed detailed correlations between well bores, and show significant intra Mishrif thinning. These reflectors imply time stratigraphic layering which is consistent with tracer study results and regional sequence stratigraphy. This new data will be used to improve the re ervoir model description.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France