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The porosity of a rock is a measure of its capacity to contain or store fluids. Porosity is calculated as the pore volume of the rock divided by its bulk volume.Two types of porosities can exist in a rock. These are termed primary porosity and secondary porosity. Primary porosity is described as the porosity of the rock that formed at the time of its deposition. Secondary porosity develops after deposition of the rock. Secondary porosity includes vugular spaces in carbonate rocks created by the chemical process of leaching, or fracture spaces formed in fractured reservoirs. Porosity is further classified as total porosity and effective porosity. Total porosity is defined as the ratio of the entire pore space in a rock to its bulk volume. Effective porosity is the total porosity less the fraction of the pore space occupied by shale or clay. In very clean sands, total porosity is equal to effective porosity. effective porosity represents pore space that contains hydrocarbon and non-clay water.1 Free formation water that is neither bound to clay nor to shale is called non-clay water. An accurate definition of effective porosity is total porosity minus volume of clay-bound water.
تقصد المساميه والنفاذيه
المساميةهي الحجم المملوء بالمائع (من الصخرة) إلى حجم الصخرة الكلي.
اما النفاذية فهي قابلية الصخرة على السماح للموائع بالمرور من خلالها بحيث تكون هذه الصخرة مشبعة100% بالمائع
اذا بتحب اترجملك للانجليزيه اترجمهالك
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porosity of no of void spaces in a bulk volume of rock and effective porosity of no of void which are interconnected to each other..