Porosity Measurement PDF

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Porosity Measurement...

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Porosity Measurement Porosity is measured in a lab by conducting tests on core samples that have been recovered during drilling a well, using a porosimeter. It can also be measured indirectly by using well logs and seismic data. A well log is a record of measurements made using various tools that are lowered into a wellbore after drilling. Density is one of many rock properties measured by logs, and if the rock type is known, porosity can be calculated, as the presence of porosity causes a decrease in the density of a rock. Porosity can also be estimated visually under a microscope on drill cuttings or core samples, or from thin section. A thin section is a very thin slice of rock that has been glued to a glass slide and viewed under a microscope. The slice is so thin that light can be transmitted through it. Blue-coloured glue is often used to reveal porosity. Permeability Measurement Permeability is measured on core samples using a permeameter. It can also be estimated indirectly from well logs and from the rate at which fluids flow out of a reservoir into a wellbore during a controlled test. Permeability is measured in Darcies, named after Henry Darcy (1803-58), a French engineer who derived a relationship among flow rate, pressure and viscosity in fluids. Reservoir rocks fall in the range of 1-50 000 mD (milliDarcies). A rock with less than 10 mD is considered tight, 10-100 mD is fair, 100-1000 mD is good and >1000 mD (equivalent to >1 D) represents excellent permeability. In conventional reservoirs,...