Sedimentology and reservoir characteristics of the Paleozoic Lower and Upper Dibsiyah member (Wajid Sandstone), Southwest Saudi Arabia

Ibrahim Taiwo Abdulkadir, King Fahd University of Petroleum & Minerals, Earth Sciences Department, Dhahran, Saudi Arabia., [email protected]

The main objective of the study is to establish from outcrops, an analog reservoir; and geological and petrophysical model for both Lower and Upper Dibsiyah member for better understanding of reservoir heterogeneity and quality in their subsurface equivalent in Rub' Al-Khali Basin. Outcrops in Wadi Ad Dawasir of Central Saudi Arabia expose sedimentary successions of the Wajid Sandstone which comprises of Dibsiyah member that is stratigraphic equivalent of the Saq-Qasim formation undivided. The Wajid Sandstone outcrop is in the southwestern part of Saudi Arabia just west of the Rub' Al Khali Basin (a frontier hydrocarbon) and occupies most of south-central Arabia including Saudi Arabia, western Oman and the United Arab Emirates.

The methods and techniques of studying the reservoir outcrop analog consist of several phases including sedimentological facies and architectural elements analysis, sample collection and measurements, laboratory determination of sandstone petrography, porosity and permeability and then, geostatistical analysis, and model construction.

Studies of outcrop analogues are a valid method for resolving sedimentary and architectural uncertainties in strongly heterogeneous reservoirs. The outcrop analog can provide information about rock body dimension, size, and orientation which are not available from the subsurface. To meet the challenge of today’s petroleum industry which is to maximize hydrocarbon recovery from reservoirs, the characterization of the outcrop analogs in terms of the heterogeneity of facies, petrophysical properties and sandstone body geometry, continuity and architecture is essential and important. This has a direct application to hydrocarbon resources exploration, development and management.