Print this pageSEDIMENTOLOGY AND RESERVOIR CHARACTERISTICS OF UPPER MIOCENE-LOWER PLIOCENE OIL AND GAS RESERVOIR SANDS IN APSHERON PENINSULA, KIRMAKY VALLEY, BAKU, AZERBAIJAN
Alaattin Sayili1, Zühtü Bati1, H. Edward
Clifton2, Dag Nummedal3,
Akif A. Narimanov4, and Gregory W. Riley5
1 Turkish petroleum Corporation, Research Center, Ankara, Turkey
2 Monterey, CA, USA
3 University of Wyoming, Laramie, WY, USA
4 State Oil Company of Azerbaijan (SOCAR), Baku, Azerbaijan
5 BP, Houston, TX, USA
The South Caspian Basin received tremendous volume of coarse clastics during Cenozoic fed by three major river systems; Paleo-Volga in the north, Paleo-Kura in the west and Paleo-Amu Darya in the east. The most important oil and gas producing reservoir sands were deposited in Paleo-Volga river system in onshore and offshore in the northern part of the South Caspian depression during Late Miocene-Early Pliocene time. The important part of the Productive Series crops out in the eastern flank of the asymmetric anticline in Kirmaky Valley. The high porosity reservoir sands of fluvial-deltaic sediments are coarser grained in upstream in onshore and grade into fines in offshore area. The most important oil and gas-producing units are Kirmaky Suite in onshore, Pereryva and Balakhany in onshore and offshore. The thick reservoir sand sheets of Kirmaky Suite possibly reflect the deposition of lacustrine complex in Late Miocene. The porosity may reach up to 35 to 40% as mostly as inter-particle initial porosity in moderate to well-sorted reservoir sands of Kirmaky Suite. The initial porosity was slightly affected due to burial compaction but intensely occluded by calcite cementation. High porosity thick reservoir sands of Pereryva and Balakhany reflect braided river deposition during lowstand in Early Pliocene in onshore and may grade into meandering river system downstream in offshore area. The porosity of fluvial channel sands may reach up to 30 to 35% as mostly inter-granular initial porosity partly destroyed due to carbonate cementation. Squeezed rip-up shale clasts and authigenic clays filling the interstitial voids may also have further reduced the porosity a bit.