An integrated geologic model of Valhall oil field for numerical simulation of fluid flow and seismic response



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Time-lapse seismic monitoring promises to be a valuable tool for reservoir engineering as it provides dynamic data over the entire field rather than the spatially limited production data. In this thesis, I develop a link between computerized reservoir simulation, rock physics, and seismic analysis. I present an example study of time-lapse seismic effects in a sequence of reservoir simulation, rock physics, and seismic forward modeling. The thesis includes a case-study of the Valhall field which I propose be used for an integrated geologic model for fluid flow and seismic simulation. I combine fluid flow simulation studies with a parallel flow simulation code IPARS to obtain computed pore pressure and oil saturation at different spatial location as a function of time. The reservoir model for fluid flow simulation input is linear and isotropic. The reservoir model has an injection well below the oil-water contact and a producer well at a shallower level. The variations of pore pressure due to injection and production cause 3-D multi-phase fluid flow in the reservoir with time. I develop a rock physics mapping code to estimate the P-wave and S-wave seismic velocities and densities for seismic forward modeling from pore pressure and water and oil saturation obtained by fluid flow simulation. The rock physics code uses Gassmann's relations for fluid substitution to compute the seismic rejection parameters. Migrated depth sections show brightening of amplitude values near the producer well as a function of time. Rejections from the production zone appear stronger indicating high oil saturation values with increasing production. I develop a case-study of the Valhall Field to make an integrated geologic model for fluid flow and seismic simulation. Based on an initial description of reservoir geology, I combine rock-physics measurements, fluid properties, geomechanics,seismic, well, and checkshot data, to build an integrated model for simulations of subsurface fluid-flow and surface seismic data.