Investigation of Gas Flow Models in Case of Micro- and Nanopore Size Reservoirs

Abstract

Conventional continuum-flow equations, such as the well-known Darcy’s law, greatly underestimate the fluid-flow rate when applied to micro and nanopore-bearing reser- voirs. This paper concentrates on the collection, interpretation and presentation of different flow models which can be used in such conditions. They are utilized on core samples which originated in a Hungarian reservoir under extreme pressure and temperature (over 1,100 bar and 200 °C). As only limited literature is available which can describe the exact flow behavior of natural gas in these conditions, comparison of the different models under these conditions can provide information for a wider understanding of these types of reservoirs. Several factors influence gas production from these unconventional formations, so the creation of an adequate material balance equation was necessary to describe pressure deple- tion and original gas in-place. Integration of this novel material balance equation with the different flow models results in a calculation algorithm which enables investigation of the reservoir behavior during production. Finally, the adaptability of this model to real produc- tion data is investigated.