Modeling Low-Salinity Waterflooding
Top Cited Papers
- 29 December 2008
- journal article
- Published by Society of Petroleum Engineers (SPE) in SPE Reservoir Evaluation & Engineering
- Vol. 11 (06), 1000-1012
- https://doi.org/10.2118/102239-pa
Abstract
Summary: Low-salinity waterflooding is an emerging enhanced-oil-recovery (EOR) technique in which the salinity of the injected water is controlled to improve oil recovery vs. conventional, higher-salinity waterflooding. Corefloods and single-well chemical-tracer tests have shown that low-salinity waterflooding can improve basic waterflood performance by 5 to 38%. This paper describes a model of low-salinity flooding that can be used to evaluate projects; shows the implications of that model and demonstrates its use to represent corefloods, single-well tests, and field-scale simulations; and gives insight into the reservoir engineering of low-salinity floods. The model represents low-salinity flooding using salinity-dependent oil/water relative permeability functions resulting from wettability change. This is similar to other EOR modeling, and conventional fractional-flow theory can be adapted to describe the process in 1D for secondary and tertiary low-salinity waterflooding. This simple analysis shows that while some degree of connate-water banking occurs, it need not hinder the process. Mixing of injected water with in-situ water delays the attainment of low salinity, potentially preventing attainment of low salinity all together if very small slugs of low-salinity water are used. This paper demonstrates the importance of mixing to modeling of low-salinity flooding and suggests addressing it in engineering calculations. Care must be taken in representing mixing appropriately in interpreting data and in constructing models. The use of numerical dispersion to represent physical dispersion in 1D, radial, and pattern simulations of this process is demonstrated (i.e., coarse-grid simulations are shown to give the same result as fine-grid simulations with an appropriately large physical dispersion). In many applications, the fine-grid simulation necessary to represent appropriate levels of dispersion is not practical, and pseudoization is necessary. We demonstrate that this can be achieved by changing the salinity dependence and shapes of relative permeability curves.Keywords
This publication has 40 references indexed in Scilit:
- Estimation of True Dispersivity in Field-Scale Permeable MediaSPE Journal, 2003
- Effect of Brine Salinity and Crude-Oil Properties on Oil Recovery and Residual SaturationsSPE Journal, 2000
- Influence of brine composition and fines migration on crude oil/brine/rock interactions and oil recoveryJournal of Petroleum Science and Engineering, 1999
- Making Sense of Water Injection Fractures in the Dan FieldSPE Reservoir Evaluation & Engineering, 1998
- Prospects of improved oil recovery related to wettability and brine compositionJournal of Petroleum Science and Engineering, 1998
- Effect of brine composition on recovery of Moutray crude oil by waterfloodingJournal of Petroleum Science and Engineering, 1996
- Core Acquisition and Analysis for Optimization of the Prudhoe Bay Miscible-Gas ProjectSPE Reservoir Engineering, 1995
- Cation and proton exchange, pH variations, and carbonate reactions in a freshening aquiferWater Resources Research, 1994
- Some Surprises in the Transport of Miscible Fluids in the Presence of a Second Immiscible PhaseSociety of Petroleum Engineers Journal, 1985
- Quantitative Evaluation of Numerical Diffusion (Truncation Error)Society of Petroleum Engineers Journal, 1971