Facies Characterization and Sequence Stratigraphy of Early Cretaceous Yamama and Sulaiy Formations, Northeastern Saudi Arabia

Abstract

The carbonates of Yamama and Sulaiy Formations were deposited during Berriasian and Valanginian time. The objective of this study is to define the depositional environments and sequence stratigraphic framework from cored wells in Northern offshore Saudi Arabia. Nineteen cored wells were described and mapped, and ten major lithofacies were defined as follow: 1- Argillaceous mudstone – wackestone (Inner ramp restricted lagoon), 2- Burrowed mudstone – wackestone (Inter-shoals area), 3- Microbial/ lithocodium peloids wackestone-packstone (patchy located on shoal's crests and also present back shoals), 4- Peloids grainstone (shoals), 5-Ooid grainstone (shoals), 6- Grapestone packstone -grainstone (locally in the center of the field between shoals), 7- Stromatoporoids packstone-grainstone (Local encrusting sponges), 8- Oncoids packstone - floatstone (associated with shoals and fore-shoals), 9-Gladocoropsis packstone- grainstone (Locally associated with stromatoporoid and peloids fore-shoals), and 10- Foraminifera rich mudstone-wackestone (open marine muds). These facies deposited mainly in middle ramp shoal complex setting and fluctuating temporally and spatially between open circulated platform and restricted lagoon. Total of 22 4th order cycles were identified in Yamama and Sulaiy Formations with a calculated periodicity of about 400-k.y., proposing a major control of the Earth's eccentricity in developing these cycles. The concentration of ooids, oncoids and grapestone facies in Lower Sulaiy formation proposing a much warmer condition compared to Upper Sulaiy and Yamama facies, which consists mainly of peloid grains and Stromatoporoids encrustation. The best reservoir facies are the Stromatoporoids, Cladocoropsis, and ooids grainstone facies.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017