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→Carbonate reservoir models
If the grainstone bars are exposed to meteoric diagenesis, significant separate vug porosity can develop, causing a loss of permeability while retaining porosity. In the dolomite environment, grainstone bars are commonly cemented with anhydrite, and intercrystalline porosity in mud-supported sediments forms the permeable facies.
If the grainstone bars are exposed to meteoric diagenesis, significant separate vug porosity can develop, causing a loss of permeability while retaining porosity. In the dolomite environment, grainstone bars are commonly cemented with anhydrite, and intercrystalline porosity in mud-supported sediments forms the permeable facies.
===Subtidal-supratidal dolomitization and sulfate emplacement reservoir model===
===Subtidal-supratidal dolomitization and sulfate emplacement reservoir model===
The subtidal-supratidal sequence is commonly dolomitized and contains anhydrite and gypsum. In the subtidal interval, dolomitized grainstones retain their intergranular pore space, except where cemented by anhydrite, and form permeable units. Dolomitization of the subtidal mud-supported sediments converts the tight, mud-supported limestones to permeable units because of the larger dolomite crystals and intercrystalline pore space. This produces two types of flow units in the subtidal interval: a dolomud-supported flow unit and a dolograin-supported flow unit. Each will have a unique porosity-permeability transform.
The subtidal-supratidal sequence is commonly dolomitized and contains anhydrite and gypsum. In the subtidal interval, dolomitized grainstones retain their intergranular pore space, except where cemented by anhydrite, and form permeable units. Dolomitization of the subtidal mud-supported sediments converts the tight, mud-supported limestones to permeable units because of the larger dolomite crystals and intercrystalline pore space. This produces two types of flow units in the subtidal interval: a dolomud-supported flow unit and a dolograin-supported flow unit. Each will have a unique porosity-permeability transform.
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===Karst-collapse reservoir model===
===Karst-collapse reservoir model===