Response relation between volcanic lithofacies and seismic facies and its application: A case study from Haerjiawu Formation in Malang Sag,Santanghu Basin

In order to study the distribution characteristics and define the exploration direction of volcanic reservoirs of Haerjiawu Formation in Malang Sag of Santanghu Basin,it is necessary to establish the response relation between volcanic lithofacies and seismic facies,and carry out the identification and prediction of volcanic rocks.The cores and casting thin sections were used to define the lithologies and lithofacies characteristics of volcanic rocks.Combined detailed logging-seismic calibration and seismic response characteristics,this paper summarized the response relation between volcanic lithofacies and seismic facies,and then predicted the volcanic reservoirs.The study result shows that overflow facies and volcanic sedimentary facies are the main lithofacies of Haerjiawu Formation,and the seismic reflection characteristics mainly are weak swing and blank lenticular pattern,middle-weak swing and weakly continuous moundy pattern,middle-strong swing and moderate continuous lamellar phase.According to the prediction,it is considered that the volcanic rocks of Haerjiawu Formation has the characteristics of central type eruption,there are mostly layered volcanos or konides,and subaerial eruption and subaquatic eruption both can be found in the sag.The distributed area of mandelstone in mid-range crater is favorable for oil-gas exploration.