Mechanisms of Primary Migration

Hydrocarbon fluids of relevance to petroleum exploration are formed as organic-rich source rocks undergo burial and are subjected to increased temperature and pressure in sedimentary basins. Many mechanisms have been proposed for the subsequent migration of the fluids in the source rocks and their expulsion into surrounding rocks, a process called primary migration. However, there is no consensus concerning the relative importance of these mechanisms and how they are coupled. We will address the role play ed by microfractures during primary migration. Flow in fractures or other high permeability pathways appears to be necessary for the hydrocarbons to migrate over large distances from the interior of thick source rock beds, but the coupling between fluid g eneration, the build-up of fluid pressure and fracture formation/closure has not been adequately investigated. In this project, we will develop a better understanding of primary migration in an integrated, cross-disciplinary study combining computationa l, experimental, and field work. Our initial hypothesis is that volume changes associated with the decomposition of kerogen and the generation of hydrocarbon fluids, result in pressure gradients that fracture the source rock and expel hydrocarbon fluids f rom it, via the fractures. We will employ advanced and versatile experimental methods, such as high resolution laboratory and synchrotron x-ray computed tomography, in combination with an extensive suite of more commonly used methods, and advanced computa tional methods that are well suited to study solid materials and multiphase fluids that are subjected to large deformations and fracturing. A better understanding of primary migration would be a valuable contribution to basin modeling, which is recognize d by the industry as an important factor in increasing exploration success. It would allow better predictions of how much hydrocarbons are expelled from the source rock.