Coarse-scale simulation of heterogeneous reservoirs and multi-fractured horizontal wells

Oil and gas reservoirs in fluvial and deltaic depositional systems comprise a significant portion of the so-called conventional resources. In these systems, the inherent reservoir heterogeneity is often the major challenge of exploitation that complicates the application and simulation of enhanced oil recovery techniques. Despite the advancements in the computational technology, fine-scale simulation of stochastically generated geomodels is not feasible as hundreds of realizations are analyzed to quantify the impact of geological uncertainty on the reservoir performance. This has motivated the development of upscaling techniques that, for highly heterogeneous permeability fields, still remains a challenge.;In the first part of this work, the effect of heterogeneity on displacement efficiency in coarse scale modeling is studied. Pore space is ranked based on flow contribution to two levels of porosity and a dual-porosity dual-permeability flow model is adapted for coarse-scale flow simulation. We use fine-scale streamline information to transform heterogeneous geomodels into a dual-continuum coarse model that preserves the global flow pathways adequately.;The proposed technique is applied and tested on two heterogeneous models with different types of fluid flow modeling (compositional and black oil). In order to evaluate the performance of the proposed technique, displacement calculations are performed on the original fine grid and on a uniform coarse grid with single-porosity and dual-porosity upscaling. We demonstrate that dual-porosity coarse models predict the breakthrough time accurately and reproduce the post-breakthrough response adequately while single-porosity models overestimate arrival time and oil recovery. By preserving large scale heterogeneities, dual-porosity coarse models are demonstrated to be significantly less sensitive to the level of upscaling, compared to conventional single-porosity upscaling. This makes the proposed upscaling approach a relevant and suitable technique for upscaling of highly heterogeneous geomodels.;Modeling of multi-fractured horizontal wells is the subject of the second part of this dissertation. Recovery from low and ultra-low permeability reservoirs have been unlocked by the introduction of horizontal well and hydraulic fracturing technology that has increased the world's hydrocarbon reserve significantly. In order to maximize the productivity from these reservoirs, numerical simulation is often used to investigate the optimized well spacing and stimulation design. Fracture properties vary during the well life and must be properly modeled to enable realistic production simulation. Production history matching of a real-life multi-fractured horizontal well in a liquid-rich Monterey formation reservoir is considered. We infer from numerical simulations that, in these systems, time-dependent fracture conductivity model is required to match early-time flush production and later-time low flow rates.;Accurate representation of the near-well dynamics is key to the realistic simulation of fractured wells. Due to the large size of these reservoirs, efficient numerical simulation requires use of large gridblocks that may not be adequate to capture the near-well dynamics. We adapt a multi-phase upscaling workflow for multi-fractured horizontal wells under natural depletion. Fine-scale simulation of the depletion process on a local well model is used to calculate a new set of gas-oil pseudo-relative permeability curves for fractured and non-fractured gridblocks. Simulation results demonstrate improvements in the accuracy of the coarse scale simulation over existing approaches.