| PDF: | |
| Time: | 2011 |
| Journal: | Natural Gas Industry |
| Volumn: | 3 |
| Issue: | 4 |
| Pages: | 28-33 |
| Type: | Other |
| Author: | Yanxiong Wu,Pujun Wang,Yanhui Wu,Lin Yan,Di Yang. |
Abstract: | Reservoir prediction is the core of volcanic gas reservoir exploration and its focus is the prediction of reservoir space development.A total of 167 outcrop and core samples were collected from the Upper Jurassic Yingcheng Formation in the Songliao Basin.Based on the observation of ordinary and cast thin sections and statistics of surface pores and analyses of poroperm characteristics,the components of volcanic reservoir space,the comparison of the primary pores,secondary pores and fissures in samples of different lithologies and lithofacies are compared,and the origins of the primary pores and secondary pores,are discussed respectively.From such discussion,the following conclusions are drawn.First,as for vesicular lava,their primary pores are most highly developed.In contrast,as for dense lava and pyroclastic lava,the proportions of the development of their primary pores,secondary pores and fissures are approximately the same.But the dense lava has relatively well developed fissures,while the pyroclastic lava has relatively well developed primary pores.As for pyroclastic rocks and sedimentary pyroclastic rocks,the development of their secondary pores and fissures are relatively large in proportions.Second,pore space of volcanic conduit is dominated by inter-gravel pores and fissures.As for explosive facies and effusive facies,the proportion of primary pores increases from bottom to top,while the proportions of secondary pores and tectoclases drop.In contrast,the pore space of extrusive facies is dominated by primary condensed shrinkage fissures and that of volcanic sedimentary facies is mainly of secondary pores and fissures.Third,volcanic rocks of different structures,such as vesicular structure,lithophytic structure,vesicular and amygdaloidal structure,rhyotaxitic structure,perlitic structure,columnar joint,intergranular texture,and melting corrosion structure,can easily form primary pores and fissures.The later-stage diagenesis of tectonism,weathering,dissolution,and devitrification enhance the development of secondary pores.The refined understandings of the internal structure of volcanic reservoirs are of great significance to their exploration and development. |