| PDF: | |
| Time: | 2010 |
| Journal: | Acta Petrologica Sinica |
| Pages: | |
| Type: | SCI |
| Author: | Huafeng Tang,Zhengshun XU,Yanhui Wu,Yanxiong Wu |
Abstract: | Volcanic reservoir flow units were classfied based on four parameters, namely porosity, permeability, RQI and FZI, using cluster anaylsis on 388 samples of the Cretaceous volcanic rock of Yingcheng Formation （K1y） in the area of well XS1 in central of the Songliao basin. The flow units can be subdivided into four classes by comparing the cluster anaylsis results with the gas production of corresponding wells, ranking decreasingly from type Ⅰ, Ⅱ,. Ⅲ to type-Ⅳ. Frequence of different level flow units show as follows, type-Ⅲ(39.2%), type-Ⅱ(33.2%), type-Ⅰ(25.0%) and type-Ⅳ (2.6%). Type-Ⅰ, the best of the flow units is composed mainly of the volcanic reservoirs with combination of high-porosity and high-permeability, or high-porosity and medium-permeability, or medium-porosity and high-permeability, and with a thickness between 10m to 20m. Type-Ⅱis predominantly medium-porosity and high-permeability, or high-porosity and medium-permeability, or low-porosity and high-permeability, and with a thickness varying from 10m to 47m. Type-Ⅲ is mainly medium-porosity and high-permeability, or medium-porosity and low-permeability, or low-porosity and medium-permeability, and with a thickness of ca. 11m to 86m.Type-Ⅳ, the worst of the flow units is generally composed of low porosity and low permeability, or ultra-low porosity and ultra-low permeability reservoirs, and shows thickness less than ten meters. Characteristics and distributions of the the volcanic flow units are controlled by both volcanic edifices and subfacies. It is the fact that central-volcano and near-volcano facies have the best potential to form type-Ⅰ and type-Ⅱflow units, while proximal facies belt type-Ⅱ and type-Ⅲ and distal facies belt type-Ⅲ and type-Ⅳ. The upper-efussive and the pyroclastics subfacies are most likely to develop flow unit of type-Ⅰ, because the former is rich in vesicle and the latter is rich in intergranular pore,. Ash fall and lower-effusive subfacies are most likely to develop flow units of type-Ⅲ and type-Ⅳ, because their primary pores and fractures are generally not well developed. Description and recognition of volcanic reservoir flow units are also presented. The work provides a foundation for 3-D modelling of the volcanic reservoir flow units. |