Peculiarities of Devonian terrigene oil and gas complexes distribution on Astrakhan arch
The article presents analysis of some peculiarities of Devonian terrigene oil and gas complex on Astrakhan arch. Significant prospects of revealing low sulfurous HC raw material are associated with this structural stage of subsalt Paleozoic. During regional stage of geological activity from 1994 to 2006 three parametric wells have been drilled. On the basis of drilling data and different investigations it was found out that the upper half of Devonian deposits (Famennian stage and most of Frasnian stage) presents an unique carbonate succession with carboniferous deposits. Possibility of forming oil prospecting traps is associated with regionally traced argillaceous caps. Presently there have place difficulties concerned correlation with Devonian terrigene deposits in western and north-western parts of periphery Astrakhan arch. For solving this problem the authors have accomplished a detailed correlation of substantial-structural composition by core test data from wells drilled in Devonian terrigene deposits. On this basis it was concluded that: terrigene deposits of Devonian age beneath horizon are well correlated towards the northern periphery of Astrakhan arch; oil and gas manifestations in wells Devonskaya and North-Astrakhanskaya-1 characterize an independent oil and gas promising play; seismic reflecting horizon in central part of the arch lies along the topmost Upper Devonian deposits. On the northern and western periphery of the arch this horizon is located along the top of Domanik argillaceous and argillo-carbonate sequence of Semiluksky horizon; gas-bearing signs were not noted beneath Domanik clays.