Summary

A previously unidentified structural closure -satellite to Saudi Arabia's Ghawar Field- has been delineated using a geostatistical integration of 3-D seismic, wellbore and gravity data. Time and initial depth mapping of Ghawar's main reservoir reflection (Arab-D), over the central part of the field's eastern flank, reveals an anomalous structural nose plunging to the east, normal to the overall Ghawar structural trend (see Figs. 1 and 2). Conversion of the time structure to depth was subsequently redone by applying revised depth conversion velocities derived using a bivariate geostatistical approach (Asli and Marcotte, 1995) in which gravity data was used as a guide variable in estimating velocities away from well control (Jeffery et al. 1996). Residual gravity maps covering this area exhibit a strong visual correlation (and a statistical correlation of 0.76) with depth conversion velocities calculated using well control. This updated depth map shows significant closure in the satellite structure and points to what could be a considerable amount of Arab-D reservoir above the local oil-water contact. This structure, as well as the presence of oil within the prospective area, have been subsequently confirmed by a well drilled on its south flank (Fig. 2).

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah