Changes

Whole core porosity is usually less than conventional plug porosity because there is a strong tendency to sample the more porous zones preferentially. Whole core samples incorporate tighter parts of the pore system that are frequently excluded from conventional samples. However, whole core porosity may be higher than that determined from conventional analysis when large solution voids are present or when the core is badly invaded by mud solids.

Whole core porosity is usually less than conventional plug porosity because there is a strong tendency to sample the more porous zones preferentially. Whole core samples incorporate tighter parts of the pore system that are frequently excluded from conventional samples. However, whole core porosity may be higher than that determined from conventional analysis when large solution voids are present or when the core is badly invaded by mud solids.

In samples having a porosity greater than 30%, sidewall core porosity is 1 to 2% lower than conventional analysis porosity. This results from slight compaction that occurs during coring. Medium and low porosity percussion sidewall samples, especially from highly cemented rocks, display porosity that is much too high due to fracturing and grain shattering. The deviation between measured porosity and true porosity becomes greater as the actual porosity decreases. Uncertainty caused by systematic variation in sidewall core porosity relative to plug analysis values can be minimized by development of correlations between sidewall core and conventional core values.<ref name=pt05r38 /> (For more on porosity, see [[Porosity]].)

In samples having a porosity greater than 30%, sidewall core porosity is 1 to 2% lower than conventional analysis porosity. This results from slight compaction that occurs during coring. Medium and low porosity percussion sidewall samples, especially from highly cemented rocks, display porosity that is much too high due to [[Fracture|fracturing]] and grain shattering. The deviation between measured porosity and true porosity becomes greater as the actual porosity decreases. Uncertainty caused by systematic variation in sidewall core porosity relative to plug analysis values can be minimized by development of correlations between sidewall core and conventional core values.<ref name=pt05r38 /> (For more on porosity, see [[Porosity]].)

==Permeability==

==Permeability==