--> ABSTRACT: 3D Modeling of Post-Depositional Shale Movement and Petroleum Generation in the Northern Baku Archipelago, South Caspian Basin, by J. J. Sawlan, P. M. Frydl, and A. A. Narimanov; #91021 (2010)

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3D Modeling of Post-Depositional Shale Movement and Petroleum Generation in the Northern Baku Archipelago, South Caspian Basin

SAWLAN, JEFFREY J., PAUL M. FRYDL, and AKIF A. NARIMANOV

Oligocene-Miocene shales are an important component of the petroleum system of the northern part of the Baku Archipelago since they both core the anticlinal structures and are the source rock. Post-depositional, diapiric movement of these shales effectively perturbs the thermal regime, affects source rock maturation, and the timing of structural growth. We developed a 3D dynamic shale model with Sextant, Mobil's proprietary basin modeling simulator, to model post-depositional movement of these shales on a detachment surface and evaluate its influence on the timing of source maturation and structural growth. Two episodes of shale movement in our model coincide with the periods of rapid sedimentation during Productive Series deposition and during post-Akchagylian time.

Pre-Akchagylian petroleum, generated in the deep basinal area, charged structures along the productive Sangachaly trend in the northern part of the Joint SOCAR-Mobil Study Area; however, it bypassed the non-productive Hamamdag trend before traps were adequately developed along this southern structural trend. A new kitchen developed to the north of the productive trend in post-Akchagylian time. Petroleum generated in this area migrated south to provide additional fill to the structures that were partially filled during the pre-Akchagylian pulse, but was not able to reach the newly formed traps along the southern structural trend.

Conventional 3D simulations of this area yield petroleum generation and expulsion results that are an artifact of the highly variable thickness of the modeled, present-day Oligocene-Miocene section and incompatible with field observations. Our 3D dynamic shale model, developed within the constraints provided by geologic and geochemical data, provides a coherent, regional view of the evolution of Oligocene-Miocene source generative areas that is also consistent with the observed distribution of commercial hydrocarbon accumulations, reservoired oil quality, and prospectivity of structures.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.