SOURCE ROCK (SHALES) PORE SPACE TRANSFORMATION DURING HYDROCARBON GENERATION

Abstract:

The main objective of this investigations is to study the factors controlling changes in rock structure during catagenetic transformation of organic matter. Hydrocarbon generation and primary migration can be controlled by numerous parameters; the most important are temperature, pressure, hydrocarbon composition, and organic matter type and content. Several experimental studies focused on the influence of these main parameters. However few dedicated works investigated how the primary structure characteristic and organic matter content affects the pore space transformation of rocks. For this purpose we simulated the primary migration processes in laboratory conditions (pyrolises and CT scanning) in order to observe the dynamics of pore space transformation. Our experiments demonstrate that after each stage of heating the rocks change their original morphology with the formation of new pores and conduits connecting the primary voids. The samples with relatively low content in organic matter revealed fewer changes in pore space morphology, in contrast to rocks rich in organic content. Our results also highlight that the newly formed pore structures are directly related with the original structure of the unaltered rocks and the primary connectivity of the organics. Most of the structural changes were observed during the sequential heating between 260 – 430 ° C; within this interval also occur the most intense reactions for hydrocarbons formation.