Constraint of volcano-stratigraphic emplacement environment on the reservoir distribution: A case analysis of rhyolitic volcanic strata in the 2nd member of Jurassic Huoshiling Formation in Wangfu fault depression, Songliao Basin, East China

Abstract

Abstract This paper takes rhyolitic volcanic strata of the 2 nd member of Jurassic Huoshiling Formation in the Wangfu fault depression, Songliao Basin as an example to discuss the environment type of volcnano-stratigraphic emplacement and distribution pattern of reservoirs and to analyze the control of volcanic strata emplacement environment on reservoir formation. Lithofacies analysis techniques can roughly determine the paleo-landform before volcnano-stratigraphic emplacement according to the types of underlying rocks. Horizon flatten techniques can basically determine the paleo-landform after emplacement according to coal bottom. There are four environment types of volcano-stratigraphic emplacement, namely, sub-sag before and after emplacement (type I), sub-sag before emplacement-low salient after emplacement (type II), low salient before and after emplacement (type III), and low salient before emplacement and sub-sag after emplacement (type IV). The drilling reveals that the volcanic strata of type I emplacement environment have the reservoir distribution pattern of excellent in the lower part and poor in the upper part because of the controlling of capturing of volatile matter, quenching of magma and deep burial dissolution. However, the volcanic strata of type III emplacement environment have the reservoir distribution pattern of excellent in the upper part and poor in the lower part because of the controlling of the weathering leaching, capturing of volatile matters and tectonic activity. The lower part of volcanic strata in type I and upper part of volcanic strata in type III are favorable exploration targets.