Heterogeneity Effects on Low Salinity Water Flooding

Abstract

We investigate the effect of heterogeneous petrophysical properties on Low Salinity Water Flooding (LSWF). We considered reservoir scale models, where the geological properties were obtained from a giant Middle East carbonate reservoir. The results are compared against a typical sandstone model. We simulated low salinity induced wettability changes in field scale models in which the petrophysical properties were randomly distributed with spatial correlation. We examined a wide range of geological realisations which mimic complex geological structures. Sandstone was simulated using a log-linear porosity-permeability relation with fairly good correlation. A carbonate reservoir from the Middle East was simulated where a much less correlated porosity permeability relationship was obtained. The salinity of formation water was set to typically observed values for the sandstone and carbonate cases. A number of simulations were then carried out to assess the flow behaviour. We have found that the general trend of permeability-porosity correlation has a key role that could mitigate or aggravate the impact of spatial distributions of petrophysical properties. We considered models with a log-linear permeability-porosity correlation, as generally observed for sandstone reservoirs. These are likely to be directly affected by the spatial distribution more than models with a power permeability-porosity correlation, which is often reported for flow units of carbonate reservoirs. The scatter of data in the permeability-porosity correlations had a relatively small impact on the flow performance. On the other hand, the effect of heterogeneity decreases with the width of the effective salinity range. Thus, uncertainty in carbonate reservoirs arises due to the ambiguity of spatial distribution of permeability and porosity would be less affects the LSWF predictability than in sandstone case. Overall, the incremental oil recovery due to LSWF was higher in the carbonate models than the sandstone cases. We observe from uncertainty analysis that the formation waterfront was less fingered than the low salinity waterfront and the salinity concentration. The dispersivity of salinity front and the water cut can be estimated for models with various degrees of heterogeneity. The outcome of the study is a better understanding of the implications of heterogeneity on LSWF. In some cases the behaviour can appear like a waterflood in very heterogeneous cases. It is important to assess the reservoir effectively to determine the best business decision.

Macroscale Modeling of Geochemistry Influence on Polymer and Low-Salinity Waterflooding in Carbonate Oil Reservoirs

“…These results indicate the favorability of heterogeneity in reservoir permeability toward low-salinity flooding at field-scale application in carbonate oil reservoirs. This is consistent with a study by Al-Ibadi et al, where LSWF in a carbonate oil reservoir was modeled through a set of LSWF’s wettability hysteresis on permeability. Also, note that the considered stratigraphic and anisotropic permeability distributions may not adequately represent the influence of LSWF in other permeability variations.…”

“…The geology considered through a sandbox is moderately representative of the normal reservoir, which is usually intersected by faults and has petrophysical properties that vary exponentially over close distances. Nonetheless, the simulation agrees with LSWF and LSP laboratory core-scale data and field-scale results modeled with log-normal permeability distribution. , …”

“…Nonetheless, the simulation agrees with LSWF and LSP laboratory core-scale data and field-scale results modeled with log-normal permeability distribution. 34 , 35 …”

The Impact of Plane Heterogeneity on Steam Flooding Development in Heavy Oil Reservoirs

“…In addition, the long-term scouring of injected water intensifies the heterogeneity of the reservoir and greatly restricts the development performance of the oilfield [6]. According to the previous research and development practice [7][8][9], we know that reservoir heterogeneity has a great influence on the development effect of water flooding [10][11][12][13].…”

The Impact of Spatially Correlated Heterogeneity and Adsorption on Modified Salinity Water in Carbonates

“…Due to the presence of various forms of heterogeneity at the reservoir scale, the scalability of the obtained responses from MSW core flooding experiments to the larger scale requires considerable precautions. The application of MSW at the oil field scale is still limited due to the unknown effects of geological uncertainty and heterogeneity on the performance of MSW flooding . Reservoir simulations are commonly used to study the impact of heterogeneity on the performance of MSW flooding.…”