Investigating the Influences of Pore-Scale Characteristics on Tight Oil Migration by a Two-Phase Pore Network Model

Abstract EN

The migration of expelled hydrocarbon from source rock into unconventional tight reservoirs is subject to different pore-scale fluid transport mechanisms as opposed to the conventional counterparts and therefore plays a crucial role in controlling the hydrocarbon distribution and accumulation in the former.

One of the different mechanisms is related to the formation of a more viscous boundary layer (BL) of brine, i.e., wetting phase fluid on pore surfaces, giving rise to the so-called BL effect.

In this work, a two-phase pore network model (PNM) that considers this BL effect is developed to study the influences of pore-scale characteristics on the oil migration process, manifested through the BL effect in tight-sandstone media.

Good agreements are reached between experimentally derived relative permeability curves and predicted ones, by applying this model to the pore-network networks extracted from the same samples.

Then, this validated model was used to evaluate the impacts of the following factors on the oil migration process: pore radius, coordination number, aspect ratio, brine viscosity, and wettability.

The results show that all factors can influence the oil migration process but at different magnitudes.

The applicability and significance of the developed tight oil migration PNM are discussed in this work.