Figure 9. Top - Typical lateral and vertical compartmentalization of reservoir zones in cavernous (karsted) carbonate rocks. Bottom - Typical porosity types and fills of cavernous reservoirs. Cave roof rocks become progressively more brecciated downward, with attending fracture, dissolution-enlarged fracture, and commonly, vuggy porosity. Cave-fill deposits variously can be: (1) cave roof-collapse breccia, which can have inter-clast porosity as well as intra-clast vuggy and fracture porosity. Conversely, original inter-clast porosity can be filled with cements and/or shale, or can be filled with porous sand; (2) impermeable shale infiltered into the cavern from above; or (3) porous or tight sand infiltered into the cavern from above. Cave roof collapse and infiltering of sand and/or shale can occur soon after karstification or later.