Preliminary Study on Stratigraphy Architecture of Middle-shasan Dongying Delta and Its Significance to Hydrocarbon Exploration

Abstract

According to integrated research on three-dimension seismic and well data,high-resolution stratigraphic architecture of Middle-Shasan Dongying Delta,Dongying sag,was well established.The sequence of Middle-Shasan Dongying Delta is controlled by abundant sediment supply from the east and the southeast of this sag,vertically consisting of thinner lower aggradational section and thicker upper progradational section.Six parasequences are recognized from the progradational section by study on thick muddy layers at deltaic front and integrated interpretation of related seismic and well data,each of which behaves as progradational superposition of bedsets representing one or more deltaic lobes.Vertical asymmetrical structure of the sequence primarily rests on both the position at the multi-order sequence architecture,and the key factor formatting the sequence and its system tracts,i.e.,abundance of sediment supply.Influence of deposition on strata frame is amplified due to ancient open-lake background and relative tectonic stability of gentle slope of Dongying sag.Higher-order sediment supply in high system tracts promotes the formation of parasequences,and the changes in ancient lakebed topography impose on the strata distributing of these parasequences.Sedimentary system or local factories restrict identification of strata frame in a greater degree,when the time or thickness span of strata unit at attention reduces.The discussion to this stratigraphic architecture will help investigation to both development,distribution of related turbidites,and their relationship to the direction and speed of delta progradation,boosting up the degrees of study and exploration of accompanying lithological reservoirs.