The Characteristics Of Organic Pore Of Southern Paleozoic Marine Shale And Its Effect On Reservoir Properties

Organic matter pores an very important pore type in shale,which can product shale gas and provided place for gas storage.This reaserch has been taken through XRD test,carbon dioxide adsorption test,nitrogen adsorption test,and spectral scanning electron microscope experiment.The comparison research about how the organic matter pores influence the shale properties is under two typical strata in southern China–Lower Cambrian Niutitang Formation and Lower Silurian Longmaxi Formation by using geostatistical methods.The contribution rate of organic pores to pore volume and surface area was calculated by regression analysis.The results showed that organic pores are circular,elliptical,“Chinese character” and slit shaped in two dimensional plane,organic matter structure just like “intestinal” in three-dimensional plane.The state of organic matter is divided into "Gathered alone" and "Associated type","Associated type" organic matter undergoes transformation,which is not conducive to the preservation of organic matter pores;"Carbon grease " oganric matter has more ability to produce hydrocarbons and create pores than the "aromatic carbon" kerogen;during the high degree of evolution,the decreasing in formation pressure and the enhancement of compaction will increase the aromatization of organic matter,resulting in lower porosity of organic matter;in the aspect of pore volume,the contribution of organic matter hole in Longmaxi Formation was higher than that in Niutitang Formation,in terms of specific surface area,the contribution of organic matter pore of Niutitang Formation was higher than that of Longmaixi Formation.Permeability increases with the decreasing of the pore radius,the decreasing of the curvature,the increasing of the effective porosity.And the increase of the large number of interconnected small circular holes is most favorable for the permeation of the formation fluid.