Primary or Secondary Organic Pore Network and Parallel Adsorption Sites in Shale: Dependency on Organic Facies and Maturity in Selected Canadian Source Rocks

Abstract

An evaluation of selected source rocks from the Mississippian marine Banff-Exshaw or Bakken and Triassic Montney/Doig formations from Alberta (Western Canada) and the Mississippian lacustrine Horton Group shale sequences from New Brunswick (Eastern Canada) were evaluated based on the issue of maturity or facies dependency of methane adsorptions, the changes in primary or secondary organic pores in shale, and primary migration of oil within various kerogen network. The amount of adsorbed and free liquids or gases and primary migration of oil within kerogen network is related to the changes of organic facies (labile versus inert) and organic maturity (oil or gas phase). This data illustrates a close relationship with the neoformed liquid hydrocarbons, change in the proportion of adsorbed and free oil and gases, and the changes in kerogen network within various shale plays. The selected adsorption and desorption capabilities in selected kerogen Type I, II, II-III shale and carbonate source rocks indicate the possible presence of parallel gas and liquid adsorptions within the labile phases in different phases of advanced maturity. They show changes in both primary and secondary pores within the organic matter of various kerogen types. This data also suggests the possible implications of multiplayer adsorptions where adsorptions are pressure and temperature dependant. The maturation time sequences of oil and gas adsorptions within various macerals (organoclasts) species change to free oil or gas phases. This process also defines the timing and volumetric changes of primary versus secondary pores in various macerals in shale. This data may also define the path of oil migration within the maceral pore structure for enhanced production within shale.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015