Characteristics of Pore Structure of Marine Shales in South China
详细信息
- 责任者：Zhong Taixian (Langfang Branch of Petroleum Exploration & Development Research Institute ; PetroChina ; Langfang ; Hebei 065007 ; China)
- 刊名：Natural Gas Industry
- 出版年：2012
- 卷期：32(9)
- 页码：p.1-4+21
- issnNo：ISSN1000-0976
- isbnNo：CN51-1179/TE
摘要
The Paleozoic shales in South China are of high maturity and in the shale formations there are multiple types of pores and fissures, particularly welldeveloped micro and nanoscale pores. A correct understanding of pore features is the basis of the study of shale gas storage, interaction between reservoir properties and fluids, adsorption, permeability, porosity and gas migration. Observation and physical test were integrated to study the pore features of marine shales in South China. The observation methods include visual inspection, optical microscope, SEM, NMR spectroscopy, and smallangle Xray scattering. They were used to describe the geometry, connectivity and fillings of pores, to count the dominant azimuth and density of pores, and to take photographs. All these data were used to determine the genetic types of shales. The physical tests include the Helium porosity test, mercury injection, low temperature liquid nitrogen adsorption, low temperature CO2 adsorption, etc. They were used to measure pore volume, size and distribution of pore diameter, pore structure, and specific surface area. All these data were used to evaluate the gasbearing capacity of shales. The following conclusions are drawn. The nanopores in the shale formations are dominated by intrakerogen, intergranular, intercrystalline and dissolution nanopores. Their pore throats are sheetlike or curved leaflike and pore diameters are in the range of 10~1000 nm. The nanopores (pore diameter: 30~100 nm) are the main part of connected reservoir space of tight reservoirs. Shale reservoir space can be classified into 5 types according to pore diameters, namely fissures （pore diameter:＞10000 nm）, macropores （pore diameter: 1000~10000 nm）, mesopores （pore diameter: 100~1000 nm）, transient pores （pore diameter: 10~100 nm）, and micropores （pore diameter:＜10 nm）.