| Abstract |
Several challenges are associated with enhancing oil and gas recovery from tight and shale reservoirs, which make up a significant portion of hydrocarbon production worldwide. Despite past efforts to characterize the properties of these reservoirs using different techniques, several geological, geochemical, and geological properties of such formations remain challenging to determine accurately. To investigate these challenges, the Bakken Petroleum System (BPS) is taken as a case study, consisting of two source rock units and two tight reservoir units. A petrographic analysis using core slabs was done and a petrophysical model was built using conventional and advanced logs to estimate properties such as porosity, permeability, water saturation, mineralogy, movable and irreducible fluids, and pore size distribution. Challenges arise from the complexity of the formation, limitations of logging tools, and inaccuracies in estimation methods. Thin laminas and borrowed intervals are difficult to detect from well logs, leading to an incorrect reading of different well logs. Additionally, cementing material and variable volumes of minerals along the reservoir interval make the estimation of cementing exponent constant inaccurate. The salinity of water, dispersed clays, and clays coatings on grains lead to low resistivity readings. Also, permeability is independent of porosity and controlled by uniform pore throat and body size distribution. The study presents lessons learned from characterizing the complex BPS and challenges that can be used to accurately characterize other tight and shale reservoirs worldwide. |
, Vamegh Rasouli 
