oa Technique of paleotectonic backstripping and assessment of hydrocarbon potential in anticline traps (South Caspian Basin)

We present an outline of a backstripping technique used for the paleotectonic reconstruction, in particular, to trace back the evolution of hydrocarbon bearing structures in the major oil and gas fields worldwide. As case study we consider three anticline structures located offshore in the South Caspian Basin (SCB) and forming a part of a lineated tectonic structure with SE trending. The study goes in parallel with similar studies on other anticline structures in the area with the results reported elsewhere. The content of organic matter in a sedimentary basin depends on its formation conditions, including rates of sedimentation and rising of anticline structures (traps for hydrocarbons). Stratigraphy and lithology of a structure can be derived in cross-sections via seismic transects. These cross-sections point not only at the current state of the structure, but give hints to its past development, that is allow to reconstruct its tectonic history under a number of plausible assumptions as to the geological development. As a second step, paleoprofiles are reconstructed which should correspond to the cross section of the same structure in the past. In particular, time moments corresponding to the end of formation of Upper and Lower Productive Series of Pliocene are important marks for SCB. From these, the rates of fold development can be derived, and the sedimentation rates for different geological epochs assessed. The sedimentation rates point at the hydrocarbon potential of the formation rocks. In this communication, we perform paleoanalysis of Aran-Deniz, Dashli and Sabail anticline structures and oil deposits in the Caspian Sea. The reconstructed sedimentation rates vary from a few tens of meters per million years to 2 km/MA and agree well with the actual results from well logging and exploration practices on these fields.