| Time: | 2015 |
| Journal: | OGP |
| Pages: | |
| Type: | EI |
| Author: | Huafeng Tang,Yuangao Zhang,Zhonglan Liu,Xianda Sun,Rixing Ding,Yan Xu,Youfeng Gao |
Abstract: | Just like the sedimentary rocks, the high resolution framework of volcanostratigraphy is very important to build the reasonable model of reservoir mode. The volcanic strata have the special time and spatial attributes that is difference to the sedimentary strata. It is necessary to analyze the characteristics of boundary and unit of volcanostratigraphy for build the framework. The framework of volcanostratigraphy of Yingcheng Formation is constructed by using the close spacings wells and high resolution 3D seismic data of QS gas field. The boundaries system is consisted by overlapping key eruptive interval unconformity boundaries(EIUB), amount eruptive unconformity boundaries(EUB), a few eruptive conformity boundaries(ECB) and intrusive contact boundaries(ICB). The EIUB probably enclose the volcanic edifices, and the ECB and EUB probably enclose the cooling unit, flow unit or deposit unit. There are 3 EIUBs according to the mark bed, such as sedimentary rock and weathered crust. 5 volcanic edifices are recognized that is constrained by the 3 EIUBs, bottom and top boundaries of volcanic rocks of Yingcheng Formation. Furthermore, 13 cooling units are identified that is constrained by the boundaries system. The volcanostratigraphy shifts from southeast to northwest at first, and then shift to northeast. The volcanic edifices in the early stage have the characteristics of thickness, small area and cone, such as the VE-1, VE-2 and VE-3 those are mainly consisted of the lava flows. The volcanic edifices in middle – later stage have the characteristics of thin, large area, sheet—shield and without obvious eruptive center, such as VE-4 and VE-5 those are mainly consisted of deposit units. The boundaries and lava flows/deposit unit control location of the zone of high porosity and permeability. The lava flows and deposit unit control the types and scale of zone of high porosity and permeability. The volcanostratigraphic boundary is the very important mark for exploration. |