Sedimentation in an Active Wrench Setting: The Upper Red Series, West Turkmenistan

Satterfield, Dorothy¹, Jonathan Redfern² (1) University of Derby, Derby, United Kingdom (2) Manchester University, UK, Manchester, United Kingdom

A new 3D survey covers several oil and gas fields in a chain extending along the Apsheron-Balkhan Sill from Azerbaijan across the Caspian into West Turkmenistan. This per­mits expanded analysis of a structure across the Nebit Dag and Burun Fields, the effects of wrench tectonics and mud diapirism on sedimentation, and identification of potential reser­voir locations in a highly variable setting.

An east-west oriented right-lateral strike-slip fault system extends from the Burun Field to the Nebit Dag Field. Faulting from Pliocene to present has produced lateral movement up 5 km. A mud diapir exploiting the fault uplifts the eastern end of the Burun Field.

In the earliest Pliocene, north to south oriented channels suggest one basin existed, with little or no impact on sedimentation from faulting. By the next stage of the early Pliocene, localized occurrences of downlap prograding southwest to northeast support uplift and ero­sion on Reidel shears. Towards the end of the early Pliocene, thickness patterns indicate that a small pull-apart basin had formed. In the middle Pliocene repeated onlap of seismic reflec­tors towards the northeast in the southern half of the fields suggests that a mud diapir rose in several episodes. By the late Pliocene channel directions, thickness patterns, and orienta­tion of onlapping and downlapping reflectors in the northern and southern halves of the fields indicate division into two sub-basins. Hence, during the Pliocene, depocenters of reservoir quality sand shifted with phases of movement of the regional wrench fault, asso­ciated Reidel shears and the local mud diapir.