Immersive diagnostics of reservoirs under WAG injection, Part II – Effect of depositional settings and dynamic spatial correlations

Abstract

Immersive visualization and diagnostics have become essential tools in the arsenal of engineers and scientists in developing innovative concepts, products, and techniques. In reservoir engineering applications, these approaches can be immensely helpful in detecting the dynamics occurring within the reservoir under complex and evolving conditions. In Part I of this study, we presented several novel immersive diagnostics quantifying displacement measures and unraveled some interesting dynamics around the injector in reservoirs undergoing Water-Alternating-Gas (WAG) injection. This article is Part II of the study on the utility of immersive diagnostics to ascertain the effect of geological formation characteristics on WAG reservoir dynamics.WAG injection can yield incremental recovery around 10% in mature oilfields. In this study, using immersive metrics, we critically investigated WAG performance of four different injection-fluid streams (pure CO2, pure methane, lean gas, and enriched gas) and three WAG injection-cycle strategies in several depositional systems. Spatial clusters of displacement behavior appeared. The relationship of oil displacement efficiency with various driving forces may depend on multiple elements. These elements include compositional variation in the residual oil close to the injector and the producers and the corresponding changes in thermophysical and multiphase flow properties. The pressure level, distance to the injector, formation permeability, and depositional units contribute to the flood performance. Over time with pressure depletion and frontal movement from the injector to producers, the distinction of these clusters dissipates.Spatial correlational analyses of displacement measures reveal interesting observations. The fluid flow of the oleic phase in channelized/turbiditic formations tends to be more inertial than diffusive. Oil displacement efficiency in the channelized/turbiditic formations depends strongly on the injector-producer connectivity via these flow conduits. In most formations, we can expect a reduction in water viscosity or an increase in the inertial force in the water, yielding more efficient oil displacement.At late times, diffusive flow dictates oil displacement in oil-water zones, wherein the advective flow of oil predominates in pockets where all three phases (oil, gas, and water) are present. In general, reservoir locations with high water-phase inertial to viscous forces wield higher oil-displacement efficiency. However, in high-permeable formations at late times, reservoir locations closer to the producers having low-permeability experience low-water inertial-to-viscous forces and relatively less oil displacement efficiency, which gets worse with the presence of all three phases.