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Integrating Seismic Inversion and Waterflood Pattern Management Planning, Upper Cretaceous Mauddud Formation Reservoir, Raudhatain Field, North Kuwait

By

 Hussain Al Ajmi1, Yousef Al Zuabi1, Rice Craig1, Haas Stephen2

(1) Kuwait Oil Company, Kuwait City, Kuwait (2) ChevronTexaco, Kuwait City,

 Integrating Seismic Inversion and Waterflood Pattern Management Planning, Upper Cretaceous Mauddud Formation Reservoir, Raudhatain Field, North Kuwait

Hussain Al Ajmi, Senior Reservoir Engineer, Kuwait Oil Company Yousef Al Zuabi, Senior Geophysicist, Kuwait Oil Company Stephen A. Haas, Senior Geophysicist, ChevronTexaco Craig Rice, Senior Reservoir Geologist, BP Kuwait Ltd.

The Raudhatain Mauddud reservoir has been under waterflood management since late 2000. To date, nine patterns have been drilled to complete the Sea Water Injection Phase 1 area. Each pattern is an inverted 9-spot of 250 acre spacing. Peripheral wells are typically less productive than crestal wells, suggestive of degradation in reservoir quality towards the flanks of the field.

To optimize Sea Water Injection Phase 2 over the flanks of the field, and right-size the patterns, a reservoir quality stratigraphic model was developed using a seismically derived porosity cube with reservoir structure and isochore maps. The porosity cube was derived by inverting the 3D seismic data using a constrained sparse spike inversion method, developing an AI to PHIE function from well control, then transforming the AI volume to a PHIE volume.

The PHIE volume clearly shows reservoir quality trends related depositional setting and faulting. Average porosity derived from the wells matches the average PHIE volume. A critical concern in the inversion was accuracy on the flanks of the structural high beyond well control where reservoir quality begins to deteriorate. An innovation technique incorporating structure into the interpolation of the low frequency earth model has proved successful. Efforts are underway to optimize pattern size to the reduced porosity volumes mapped on the flanks.