Effects of microporosity on permeability and sonic velocity of Miocene carbonates and an approach to relate micrite microtextures with microporosity occurrences in Miocene carbonate reservoirs of offshore Sarawak, Malaysia

The quantification of microporosity leads to determine its empirical relationships with permeability and sonic velocity of Miocene carbonate reservoirs. These relationships can be used for a better understanding of the reservoir systems. This study on Miocene carbonate reservoirs of Central Luconia, offshore Sarawak, Malaysia revealed an inverse relationship between microporosity and permeability. Microporosity has its effects on porosity-permeability correlation. The relationship between porosity and permeability of Miocene carbonate reservoirs shows a better correlation when microporosity is deducted from the total porosity of the reservoir. Microporosity in carbonate reservoirs of Central Luconia, affects the elastic properties of the rock. Microporosity reduces the sonic velocity of the carbonate reservoirs. Both P and S wave velocities of Miocene carbonates of Central Luconia, show an inverse relationship with microporosity. Microporosity affects sonic velocity and permeability in carbonate reservoirs and influences the assessment of ultimate recovery of hydrocarbon. Microporosity can occur in grain, cement or matrix and it is related to the diagenetic history of the carbonate reservoirs. Depending on the crystallometry and morphometry of micrite particles, microporosity can vary both in amount and in nature.