Figure 3. Sand/shale mixture model used to derive the noncompacted porosity of the formation. The porosities pSd and pSh are the noncompacted porosity corresponding to a clean sand and a perfect shale, respectively. The porosity is at a maximum for the two end-members of the model and is at a minimum when clays fill the pores of grain-supported sand (center panel). For the formations studied in this paper, sediments are mostly clean and clayey sands, with a high carbonate content (20%-50% by weight).

Figure 3. Sand/shale mixture model used to derive the noncompacted porosity of the formation. The porosities

_Sd and

_Sh are the noncompacted porosity corresponding to a clean sand and a perfect shale, respectively. The porosity is at a maximum for the two end-members of the model and is at a minimum when clays fill the pores of grain-supported sand (center panel). For the formations studied in this paper, sediments are mostly clean and clayey sands, with a high carbonate content (20%-50% by weight).