Oil Exploration in Central Arabian Arch Using Landsat Images

Floyd F. Sabins

Beginning in 1988, the Chevron Remote Sensing Research Group and Aramco digitally processed and interpreted seven Landsat thematic mapper images of the Central Arabian Arch for two purposes: 1. Map geology at 1:250,000 scale; 2. Identify anomalies that may be surface expression of structural traps. The well-exposed outcrops are predominantly marine strata of Mesozoic age with regional dips to east and southeast at less than 2°. This structural setting lacks the patterns of arcuate and offset beds that characterize folds and faults in more strongly deformed terrains. Therefore we developed a model to predict the image expression of structures in this homoclinal terrain. We based the model on oil fields in the Arabian Gulf region that are drape anticlines overlying hig -angle faults that offset basement rocks and Paleozoic strata. The anticlines grade upward into structural terraces caused by flattening of the regional dip. Erosion of the terraces produces subtle topographic and stratigraphic anomalies that are recognizable on the images.

The model was used to interpret a number of image anomalies. We field-checked the anomalies and eliminated a few. Aramco then acquired seismic data for several of the more promising anomalies that confirmed the presence of subsurface structure. Drilling resulted in discovery of Raghib and Dilam fields that produce from the Unayzah Sandstone (Permian). Initial production in the discovery and development wells ranges from 3000 to 4300 BOPD with gravity of 44 to 46° API. The source of this high-quality oil is the Qusaiba Shale (Silurian). The new discoveries are approximately 100 km from the nearest fields. Less than two years elapsed from beginning of digital image processing to completion of the discovery wells.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California