[[:file:Mth16Ch7Figure7-1.jpg|Figure 1]] is a flowchart for one such scanning technique. Note that it has two paths, one for [[Lithofacies and environmental analysis of clastic depositional systems|clastics]] and one for [[carbonate]]s. In the clastic case, the [[Basic_open_hole_tools#Resistivity|resistivity log]] is the primary reconnaissance measurement because clastics tend to consist of reservoirs surrounded by [[shale]]s of slowly varying resistivity. The changes in resistivity due to changes in fluid content of the reservoirs tend to stand out against this relatively constant background. On the carbonate path, on the other hand, formation resistivities tend to vary widely with changing rock types, and commonly there are few shales against which to measure changes. In this case, the [[Basic_open_hole_tools#Porosity|porosity log]] is the primary reconnaissance measurement. By first finding the porous zones, those with the capacity to hold fluids (of any type) can be identified. | [[:file:Mth16Ch7Figure7-1.jpg|Figure 1]] is a flowchart for one such scanning technique. Note that it has two paths, one for [[Lithofacies and environmental analysis of clastic depositional systems|clastics]] and one for [[carbonate]]s. In the clastic case, the [[Basic_open_hole_tools#Resistivity|resistivity log]] is the primary reconnaissance measurement because clastics tend to consist of reservoirs surrounded by [[shale]]s of slowly varying resistivity. The changes in resistivity due to changes in fluid content of the reservoirs tend to stand out against this relatively constant background. On the carbonate path, on the other hand, formation resistivities tend to vary widely with changing rock types, and commonly there are few shales against which to measure changes. In this case, the [[Basic_open_hole_tools#Porosity|porosity log]] is the primary reconnaissance measurement. By first finding the porous zones, those with the capacity to hold fluids (of any type) can be identified. |