Changes

==Wellbore scale heterogeneities==

==Wellbore scale heterogeneities==

[[file:geological-heterogeneities_fig1.png|thumb|left|{{figure number|1}}Levels of reservoir heterogeneity. (Modified from Weber.<ref name=pt06r153>Weber, K. J., 1986, How heterogeneity affects oil recovery, in Lake, L. W., Carroll, H. B. J., eds., Reservoir Characterization: Orlando, FL, Academy Press, p. 487–544.</ref>)]]

[[file:geological-heterogeneities_fig1.png|thumb|left|300px|{{figure number|1}}Levels of reservoir heterogeneity. (Modified from Weber.<ref name=pt06r153>Weber, K. J., 1986, How heterogeneity affects oil recovery, in Lake, L. W., Carroll, H. B. J., eds., Reservoir Characterization: Orlando, FL, Academy Press, p. 487–544.</ref>)]]

[[file:geological-heterogeneities_fig2.png|thumb|{{figure number|2}}Typical vertical stratification and permeability profiles of (a) fining- or thinning-upward and (b) coarsening- or thickening-upward sequences. ''Fining'' and ''coarsening'' refer to average relative grain size of individual laminae and beds, and ''thinning'' and ''thickening'' refer to the relative thickness of Individual laminae and beds.]]

[[file:geological-heterogeneities_fig2.png|thumb|300px|{{figure number|2}}Typical vertical stratification and permeability profiles of (a) fining- or thinning-upward and (b) coarsening- or thickening-upward sequences. ''Fining'' and ''coarsening'' refer to average relative grain size of individual laminae and beds, and ''thinning'' and ''thickening'' refer to the relative thickness of Individual laminae and beds.]]

Elements of wellbore heterogeneities include the pore network ([[Pore system fundamentals|pores and pore throats]]), [[Porosity#Influence of textural parameters on porosity|grain size and composition, grain packing]], lamination and [[bedding style]]s, [[sedimentary structure]]s, lithofacies, and [[vertical stratification sequence]]s. These properties can be readily described in a numerical or quantitative fashion because of the usual availability of rock samples and well logs. Rock [[Conventional coring|core]]s provide the best information on lithofacies and stratification sequences, plug or whole core [[porosity]], [[Permeability|permeability]], and [[Water saturation|fluid saturation]] (if [[oil-based drilling mud]] was used during coring). The use of [[Quick-look lithology from logs#Log shapes|log shapes]] for facies recognition, as well as [[Sidewall coring|sidewall samples]], [[Basic open hole tools#Microresistivity|micrologs]], and [[Dipmeter analysis|dipmeter]] tools can also provide indirect information on lithofacies and stratification types. (For more on lithofacies, see [[Lithofacies and environmental analysis of clastic depositional systems#Clastic depositional lithofacies and environments|Clastic lithofacies]] and [[Carbonate reservoir models: facies, diagenesis, and flow characterization#Carbonate sediments and environments|Carbonate lithofacies]]). [[Pore network]]s, [[grain size]] characteristics, and [[mineralogy]] can be analyzed by routine [[Thin section analysis|thin section petrography]] as well as by [[SEM, XRD, CL, and XF methods#X-ray diffraction (XRD)|X-ray diffraction]], [[Scanning electron microscopy (SEM)|scanning electron microscopy]], [[capillary pressure]] measurements, and [[petrographic image analysis]] (see [[Reservoir quality]]). Analysis of all or most of these properties is essential for adequate reservoir description because these properties provide the database and thus the foundation for reservoir description at larger scales.  

Elements of wellbore heterogeneities include the pore network ([[Pore system fundamentals|pores and pore throats]]), [[Porosity#Influence of textural parameters on porosity|grain size and composition, grain packing]], lamination and [[bedding style]]s, [[sedimentary structure]]s, lithofacies, and [[vertical stratification sequence]]s. These properties can be readily described in a numerical or quantitative fashion because of the usual availability of rock samples and well logs. Rock [[Conventional coring|core]]s provide the best information on lithofacies and stratification sequences, plug or whole core [[porosity]], [[Permeability|permeability]], and [[Water saturation|fluid saturation]] (if [[oil-based drilling mud]] was used during coring). The use of [[Quick-look lithology from logs#Log shapes|log shapes]] for facies recognition, as well as [[Sidewall coring|sidewall samples]], [[Basic open hole tools#Microresistivity|micrologs]], and [[Dipmeter analysis|dipmeter]] tools can also provide indirect information on lithofacies and stratification types. (For more on lithofacies, see [[Lithofacies and environmental analysis of clastic depositional systems#Clastic depositional lithofacies and environments|Clastic lithofacies]] and [[Carbonate reservoir models: facies, diagenesis, and flow characterization#Carbonate sediments and environments|Carbonate lithofacies]]). [[Pore network]]s, [[grain size]] characteristics, and [[mineralogy]] can be analyzed by routine [[Thin section analysis|thin section petrography]] as well as by [[SEM, XRD, CL, and XF methods#X-ray diffraction (XRD)|X-ray diffraction]], [[Scanning electron microscopy (SEM)|scanning electron microscopy]], [[capillary pressure]] measurements, and [[petrographic image analysis]] (see [[Reservoir quality]]). Analysis of all or most of these properties is essential for adequate reservoir description because these properties provide the database and thus the foundation for reservoir description at larger scales.