Primary Depositional Controls on Source Rock Development in the Western Former Soviet Union: a Sequence Stratigraphic Perspective

Carola Hulka, David Kemp, Ben Kilner, Domenico Lodola, Ailsa Messer, and Mike Simmons
Neftex Petroleum Consultants Ltd, Abingdon, United Kingdom

Understanding the primary depositional controls on source rock development is critical for reducing risk in the exploration and development of petroleum systems. Here, we explore how eustatic, geodynamic and transient palaeoclimatic processes can explain the spatial and temporal distribution of these facies in the western former Soviet Union.
A number of economically important source rocks are known from the western former Soviet Union, including: the Late Oligocene-early Miocene (the Maykop and Diatomaceous Suites); the Upper Jurassic-Lower Cretaceous (the Bazhenov Formation and equivalents); the Upper Devonian (Domanik type facies); and the early Toarcian (the Togur Formation).
The development and distribution of dysoxic/anoxic conditions during the deposition of the Oligocene-Miocene Maykop facies of the Para-Tethys region, and the Jurassic-Cretaceous Bazhenov Formation of West Siberia, is most readily explained as a consequence of palaeoceanographic changes (such as basin isolation) controlled by regionally important geodynamic processes. By way of contrast, the development of the Upper Devonian and early Toarcian organic-rich facies owes more to transient global palaeoceanographic and palaeoclimatic events which led to globally distributed oceanic anoxia and enhanced preservation of organic carbon.
A robust sequence stratigraphic framework developed in the Middle East and applied in the western former Soviet Union allows for the integration and correlation of available public-domain well and outcrop sections. Importantly, the development of this sequence stratigraphic model enables detailed mapping and isopaching of source rock intervals (constrained by underlying tectonic elements) and facilitates their prediction away from areas of detailed study.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece