Geological Interpretation of Acoustic Inversion for the Complex Frasnian Carbonates (Inzyreiskoye Field of North Russia)

The Inzyreiskoye field is located in the Timano-Pechorskaya oil-and-gas province of Russia. The productive intervals are the Middle Devonian terrigenous and Upper Devonian carbonate complexes characterized by the complicated geological structure with sharp facies variations by lateral, pinch-out zones presence, large number of tectonic faults and non-anticline traps. The field is under investigation for a long time and the traditional results of the seismic and logging data sequential interpretation were sets of structural and predicted maps provided by 2D attribute analysis.<br>The geological structure complication often provides ambiguousness of the results interpretation. In order to increase the results reliability, specify the limits of lithofacies changes and receive 3D models of the rocks properties in 2005 in the southern part of the field acoustic inversion was carried out in its common variant (full stack inversion) for the first time. The most interesting results were received for the thick Upper Devonian reef complex. We managed to reliably perform the facial classification and particularly define the high cavernosity and karsting zones which can provide increased production and in extremis even emergency situations in wells. There is the possibility of the elevated risk zones insulation via the impedances values.