Impact of contrasting paleoclimate on carbonate reservoir architecture: Cases from arid Permo-Triassic and humid Cretaceous platforms in the south and southwestern Iran

Carbonate platforms formed and evolved in different climatic conditions (i.e. arid vs. humid) show diverse features which is reflected in their internal reservoir architectures. The Permo-Triassic Dalan–Kangan and Upper Cretaceous Sarvak carbonates host huge hydrocarbon accumulations in south and southwest Iran. These successions, along with their equivalents in the Middle East, are among the best examples of carbonate platforms formed and evolved in two different climatic conditions (i.e. arid and humid, respectively). Disparate climatic conditions had led to drastic changes in their facies characteristics, later diagenetic alterations, reservoir characteristics and architecture. To investigate the impact of paleoclimatic conditions on their reservoir characteristics, integrated sedimentological, geochemical and reservoir zonation studies are carried out on (core) samples from selected successions in seven oil and gas fields across the Dezful Embayment, in SW Iran and in the Persian Gulf. Integration of detailed sedimentological studies with petrophysical evaluations has resulted in the perception of some field-scale variations in these carbonate sequences.