Changes

Reservoirs are inherently heterogeneous assemblages of depositional facies and subfacies (for more information, see [[Lithofacies and environmental analysis of clastic depositional systems#Clastic depositional lithofacies and environments|Clastic lithofacies]] and [[Carbonate facies#Basic carbonate facies zones|Carbonate lithofacies]]), each with characteristic and commonly differing sediment textures, stratification types, and bedding architectures. Variability is compounded by postdepositional alterations of the strata, such as through compaction, cementation, and tectonic deformation. Geological heterogeneities have been classified in a variety of ways according to their size or scale; the common categories, used here, are ''wellbore, interwell'', and ''fieldwide'' scales of heterogeneity ([[:file:geological-heterogeneities_fig1.png|Figure 1]]).

Reservoirs are inherently heterogeneous assemblages of depositional facies and subfacies (for more information, see [[Lithofacies and environmental analysis of clastic depositional systems#Clastic depositional lithofacies and environments|Clastic lithofacies]] and [[Carbonate facies#Basic carbonate facies zones|Carbonate lithofacies]]), each with characteristic and commonly differing sediment textures, stratification types, and bedding architectures. Variability is compounded by postdepositional alterations of the strata, such as through compaction, cementation, and tectonic deformation. Geological heterogeneities have been classified in a variety of ways according to their size or scale; the common categories, used here, are ''wellbore, interwell'', and ''fieldwide'' scales of heterogeneity ([[:file:geological-heterogeneities_fig1.png|Figure 1]]).

Heterogeneities at the wellbore scale affect matrix [[permeability]], distribution of residual oil, directional flow of fluids, potential fluid-rock interactions, and formation damage. Heterogeneities at the interwell scale affect fluid flow patterns, drainage efficiency of the reservoir, and vertical and lateral sweep efficiency of secondary and tertiary recovery projects. Heterogeneities at the fieldwide scale determine the in-place hydrocarbon volume, areal distribution, and trend of hydrocarbon production.

Heterogeneities at the wellbore scale affect matrix [[permeability]], distribution of residual oil, directional flow of fluids, potential fluid-rock interactions, and formation damage. Heterogeneities at the interwell scale affect fluid flow patterns, drainage efficiency of the reservoir, and vertical and lateral sweep efficiency of [[Waterflooding|secondary and tertiary recovery projects]]. Heterogeneities at the fieldwide scale determine the in-place hydrocarbon volume, areal distribution, and trend of hydrocarbon production.

==Wellbore scale heterogeneities==

==Wellbore scale heterogeneities==