Controlling factors of high-quality volcanic reservoirs of Yingcheng Formation in the Songnan gas field

Abstract

Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field. Core, seismic, and measurement data were used to study the lithologies, facies, reservoir porosity, and reservoir types of the volcanic rocks in the Songnan gas field. The primary controlling factors and characteristics of the high-quality volcanic reservoirs of the Yingcheng Formation in the Songnan gas field were investigated, including the volcanic eruptive stage, edifice, edifice facies, cooling unit, lithology, facies, and diagenesis. Stages with more volatile content can form more high-quality reservoirs. The effusive rhyolite, explosive tuff, and tuff lava that formed in the crater, near-crater, and proximal facies and in the high-volatility cooling units of large acidic-lava volcanic edifices are the most favorable locations for the development of the high-quality reservoirs in the Songnan gas field. Diagenesis dissolution, which is controlled by tectonic action, can increase the size of secondary pores in reservoirs. Studying the controlling factors of the high-quality reservoirs can provide a theoretical basis for the prediction and analysis of high-quality volcanic reservoirs.