Abstract
The objective of this study was to construct a detailed facies-based sequence stratigraphic framework using cores, logs and available isotope data for reservoir characterization and development. This framework, when integrated with petrophysical data, should lead to better reservoir and simulation models. This study will also help refine our understanding of global climate and sea-level history in the Early Cretaceous. The succession consists of a composite sequence of seven highfrequency sequences and is dominated by 400,000 years (Ky), fourth-order sequences and 100 Ky parasequences. Sequence 1 and part of sequence 2 formed the transgressive systems tract (TST) of the composite sequence with a deeper open-platform of Palorbitolina-Lithocodium wackestone. The remaining subsequences developed a platform rimmed by rudist rudstone and backed by rudist floatstone back-bank and lagoonal fine skeletal peloidal packstone; slope facies are fine skeletal fragmented packstone. Aggradational subsequences 3 to 5 make up the early highstand systems tract (HST). Progradational subsequences 6 and 7 are within the late HST marking the deterioration of the Offneria rudist barrier and deposition of widespread lagoonal deposits. Shu'aiba deposition on the platform was terminated by longterm sea-level fall, followed by exposure and karsting. The presence of 400-Ky fourth-order sequences and 100-Ky parasequences, which were driven by long- and short-term eccentricity, respectively, suggests that early Cretaceous climate may have been cooler than generally believed and was not an ice-free greenhouse world. This is pertinent to the debate concerning whether the Aptian was a time of green-house climate typified by small precessionally-driven sea-level fluctuations, or whether there were small ice sheets at the poles that generated moderate-amplitude, fourth order fluctuations, driven by eccentricity. ... (Publisher extract)