Composition and Gas-Filled Pore Characteristics of Permian Organic Shale in Southwest Fujian Depression, Cathaysia Landmass
详细信息
- 责任者：Fang Lizhi (Key Laboratory of Computational Geodynamics ; Chinese Academy of Sciences ; Beijing 100049 ; China) ; Ju Yiwen
- 刊名：Earth Science Frontiers
- 出版年：2013
- 卷期：20(4)
- 关键词：页岩气 ; shale gas ; 孔隙结构 ; pore structure ; 福建 ; Fujian Province
- 页码：p.229-239
- 图表：illus., 5 tables, 57 refs.
- 分类号：1003
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
Cathaysia landmass has undergone multi-stage tectonic movements of nappe structure and extensional structure since the Palaeozoic Era.In this paper,through experimental testing of the organic shale samples which collected in the Xianting,Qudou area in Southwest Fujian,the organic parameters,mineral composition and gas pore structure were analyzed.This paper aims to supply theoretical basis for characterizing shale reservoir features and predicting shale gas exploration prospect in Southwest Fujian,Cathaysia landmass.The results show as follows:(1) according to the TOC residual carbon analysis experiment,fluorescence microscope and microscope photometer experiment,it is considered that the Permian shale in Southwest Fujian is medium TOC abundance,generally 0.15%-2.71%;the degree of organic maturation evolution is high,between 3.51% and 4.33%;(2) reservoir mineral composition,through X-ray diffraction experiment in whole rock analysis,indicates that clay mineral content is slightly high,generally accounting for 38.2%-49.6%,dominant one of illite,and chlorite and smectite as secondary;among the common non-clay minerals,quartz is dominant,all accounting for more than 45%;the abundance of potassium feldspar and plagioclase is less,generally 1%-2.3%;(3) in reservoir porosity and permeability aspects: effective porosity is generally between 0.3%-11.4%,and permeability is between(0.0065-0.987)×10-3 μm2;the low temperature liquid nitrogen adsorption experiment was used to analyze nano-scale pore,and it is concluded that part of small pores(2-50 nm) make a significant contribution to pore volume and specific surface area,followed by micropores(less than 2 nm) and large pores(more than 50 nm).In addition,the specific surface area and the total cumulative pore volume present a strong positive correlation.The relationship among nano-pore cumulative specific surface area,cumulative pore volume and pore size indicates that the shale gas of South Cathaysia landmass mainly occurred in micropores(less than 2 nm) and in a part of small pores that less than 10 nm.According to the evaluation criterion of shale gas reservoirs,Permian marine-terrigenous shales are rich in organic matter,high evolution degree of organic matter,suitable shale mineral composition,thickness,pore structure,meeting the minimum standards of shale gas development,indicating good exploration and development prospects.