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Dolograinstones are dominated by intercrystalline/intergranular porosity with a narrow size range of pore throats that results in most of the nearly 20% porosity being effective to oil flow. In contrast, dolopackstones are less porous and contain both moldic and intercrystalline/intergranular porosity. Their bimodal pore system results in a wider range of pore throat size and more ineffective porosity.
The typically fine-crystalline dolomite results in low-permeability reservoirs, but a long production history for the field attests to good connectivity. Meteoric overprint produced moldic and enhanced intercrystalline porosity leading to patchily distributed zones of higher porosity and permeability, whereas evaporate cementation and replacement further complicates the reservoir quality distribution.