| The quantitative prediction of the continuum flow descriptors of reservoir rock, such as the absolute permeability, the relative permeabilities, the capillary pressures, the formation resistivity, etc., is essential in earth sciences and---in particular---in petroleum engineering. Usually, the theoretical prediction of rock transport properties is performed in two steps: (1) A model of the rock microstructure is formulated, and (2) a discretized field equation, such as Stokes' equation, is numerically solved on this model.; We present an integrated procedure to estimate the absolute permeability of unconsolidated and consolidated reservoir rock directly from their microscopic 3D images. Both computer-tomography and computer-generated images of reconstructed reservoir rock samples can be used as input. A general physics-based depositional model is developed to reconstruct natural sedimentary rock, and generate 3D images of the pore space at an arbitrary resolution. This model provides a detailed microstructure of the rock, which serves as boundary conditions in modeling fluid transport. A version of the lattice Boltzmann method is implemented to simulate the viscous fluid flow in the pore space of natural and computer-generated sandstone samples. The absolute permeability is calculated directly from the simulated fluid velocity field in the sample.; Our approach to numerical reconstruction of the internal geometry of natural sedimentary rock consists of three main steps: sedimentation, compaction, and diagenesis, followed by the verification of rock mechanical properties. The dynamic geologic processes of grain sedimentation and compaction are simulated by solving a dimensionless form of Newton's equations of motion for an ensemble of grains. The diagenetic rock transformation algorithm accounts for the spatial distribution of cement overgrowth under different hypotheses.; The depositional model enables one to investigate the interplay between diagenetic processes and the alteration of microstructure and transport properties in the formation of sedimentary rocks, and study effectively the evolution of sedimentary rock microstructure (its porosity, permeability, and strength) during arbitrary rock deformations, thus enhancing general understanding of deformation and fracture behavior of hydrocarbon and gas reservoirs. Our results suggest the possibility of reconstructing sedimentary rock so that the rock's geometrical, transport, and mechanical properties are matched simultaneously. |
