Upscaling Low-Salinity Benefit from Laboratory Scale to Field Scale: An Ensemble of Models with a Relative Permeability Uncertainty Range

Abstract

Summary The distribution of low-salinity benefit for an ensemble of models is required to evaluate low-salinity enhanced oil recovery (OREC) projects. To enable this, low-salinity pseudorelative permeability curves are required to estimate the benefit of low-salinity waterflooding at the field level. We present how the low-salinity benefit can be propagated through an ensemble of full-field models in which each simulation case could have a set of distinctive high-salinity pseudos. A 0.5-ft vertical resolution sector and its 10-ft upscaled counterpart are used. Relative permeability curves and the low-salinity benefit from corefloods are used in the high-resolution sector to create profiles. Pseudohigh- and low-salinity curves are generated for the upscaled sector by history matching high-salinity and incremental low-salinity profiles. Low-salinity benefit is typically measured from corefloods and the same benefit is often assumed at the field scale. Our results show that generating low-salinity curves for high-salinity pseudos using low-salinity benefit from corefloods slightly underestimates the true low-salinity benefit at field scale estimated from high-resolution models. This conclusion is consistent for two extreme relative permeability scenarios tested (i.e., a high-total-mobility unfavorable fractional flow and low-total-mobility favorable fractional flow). Including capillary pressure in high-resolution models was crucial. We would have come to another conclusion if we had not used capillary pressure in fine-grid simulation as approximately one-third of the benefit of low-salinity waterflooding was attributable to more favorable capillary pressure under low-salinity injection. We demonstrate how a set of high-salinity relative permeability data obtained from corefloods, which encompasses a range for fractional flow and total mobility, can be included in ensemble modeling appropriately and how low-salinity benefit could be estimated for such an ensemble. It is adequate to generate low-salinity curves for bounding high-salinity sets of curves. The bounding low-salinity curves can then be used to estimate low-salinity curve for any interpolated high-salinity curve. This workflow significantly simplifies the process of generating the distribution of low-salinity benefit corresponding to an ensemble of models which may be calibrated to limited history.

Oil/Brine Screening for Improved Fluid/Fluid Interactions during Low-Salinity Water Flooding

“…Sulfates and divalent ions exhibit minimal differences, typically within two or three times, while monovalent concentrations tend to cluster approximately one order of magnitude greater than divalent ones. Based on this graph, we can add up the concentrations to get to a working concentration of around 5000 ppm; this aligns with the findings of Kazemi Nia Korrani and Jerauld [5], suggesting this salinity value is a compelling choice or proposing upscaling in LSWF/SWF projects. The experimental analysis conducted reveals that the brine/oil properties play a significant role in enhancing fluid/fluid interaction mechanisms.…”

“…A good example is presented by Sorop and collaborators [3], where the implementation of LSWF replaced de-sulfated water flooding, using the same treatment plant and reducing costs, and this idea can be also applied for brownfields management and also offshore operations as presented. LSWF/SWF have proved to increase the recovery factor (RF) between 6 and 20% as presented by Masalmeh and collaborators in 2019 [4] and Kazemi in 2022 [5]. This shows the potential of this method to replace conventional water flooding or other EOR methods.…”