Reservoir characteristics, formation mechanisms and petroleum exploration potential of volcanic rocks in China

Abstract

Characterized by complex lithology and strong heterogeneity, volcanic reservoirs in China developed three reservoir space types: primary pores, secondary pores and fractures. The formation of reservoir space went through the cooling and solidification stage (including blast fragmentation, crystallization differentiation and solidification) and the epidiagenesis stage (including metasomatism, filling, weathering and leaching, formation fluid dissolution and tectonism). Primary pores were formed at the solidification stage, which laid the foundation for the development and transformation of effective reservoirs. Secondary pores were formed at the epidiagenesis stage, with key factors as weathering and leaching, formation fluid dissolution and tectonism. In China, Mesozoic-Cenozoic volcanic rocks developed in the Songliao Basin and Bohai Bay Basin in the east and Late Paleozoic volcanic rocks developed in the Junggar Basin, Santanghu Basin and Tarim Basin in the west. There are primary volcanic reservoirs and secondary volcanic reservoirs in these volcanic rocks, which have good accumulation conditions and great exploration potential.

The characteristics of Carboniferous volcanic lithofacies and volcanic reservoirs of Ke‐Bai Fault Belt, northwestern Junggar Basin

“…The volcanic sedimentary facies, as a kind of lithofacies in which sedimentary rocks and volcanic rocks coexist, are mostly formed in the dormancy or late volcanic cycle (Hou et al, 2009; Li et al, 2017; Mao et al, 2015). The volcanic sedimentary facies are usually far away from the crater.…”

“…The deep fluid can dissolve materials that fill in the pores and increase fracture width, which favours the reservoir space. The interaction of fractures and deep fluid can form a virtuous cycle to improve physical property of volcanic reservoirs (Mao et al, 2015; Zhang et al, 2017).…”

“…In most cases, the cements come from pore water (Hou et al, 2009). Cementation not only acts as important role in the transformation of sediments into sedimentary rocks, but also turns out to be main factors for the decrease of porosity and permeability in sedimentary strata (Li et al, 2008; Mao et al, 2015). The cementation takes place in various stages of diagenesis and presents the characteristics of generation.…”

Pore Distribution Characteristics of the Igneous Reservoirs in the Eastern Sag of the Liaohe Depression

“…At present, there are many igneous reservoirs in Songliao, Bohaiwan, Junggar and Sichuan Basins which show great exploration potential [8,9]. In recent years, great progress has been made in the examinations of volcanic reservoirs, including studies regarding the classifications of lithology and lithofacies [10][11][12][13][14], variations in porosity and permeability [15,16], classification of reservoir space types [17][18][19], forming mechanisms [20][21][22][23], reservoir seismic identification [24][25][26][27], reservoir evaluation and prediction [9,12,18,21], and so on.…”

Vesicle distribution in acidic lava flow units in the rift basins of NE China: implications for petroleum reservoir exploration

“…Acidic lava successions represent important petroleum reservoir formations in the Cretaceous rift basins of NE China (Shan et al, 2013;Chen, 2015), and vesicles represent the main source of porosity within hydrocarbon-bearing lavas (Feng et al, 2014;Mao et al, 2015). The acidic lava successions comprise several lava flow units, which are divided by eruptive unconformity boundaries (Cheng et al, 2014).…”