Classification of Microporosity in Carbonates: Examples from Miocene Carbonate Reservoirs of Central Luconia, Offshore Sarawak, Malaysia

Abstract

U.S.A., Miocene carbonate reservoirs may contain appreciable amount of microporosity in grain, cement or matrix. Depending on the crystallometry and morphometry of micrite particles, microporosity can vary both in amount and in nature. Different kinds of micrite microtextures may produce different types of microporosity. This study proposes a classification of micrite microtextures and microporosity. Four different types of micrite microtextures are classified in this study; these are rounded micrites, subrounded micrites, microrhombic and polyhedral micrites, and compact anhedral micrites. Four different types of micropores are classified based on their pore sizes. These are very fine, fine, medium, and coarse micropores. The classification of microporosity allows its occurrence in carbonate reservoirs to be explained depending on micrite microtextures. The classification of micropores in terms of their micrite microtextural occurrence lead us to define the micropores that are contributing to the permeability of the reservoirs and allow fluid flow in carbonates. The classes of micropores together with the corresponding micrite microtextures of their occurrences help to define the potential reservoir rocks in terms of micrite microtextures.

Insights into the Pore Structure of Strong Heterogeneous Carbonates in the Mesopotamian Basin

“…The green algae moldic pore is the most common MO in the Mishrif carbonates because green algae are abundant and more easily dissolved due to their aragonitic mineral component. 56 The BC is mainly founded in dolomitized grainstone (Figure 5F) and rudstone. It refers to the pores between dolomite crystals originated from dolomitization and relatively rare than other pore types.…”

“…In this study, it refers to the pore with sizes of less than 30 μm. 56 It includes the fine-sized grain-related micro moldic pores or micro interparticle pores (Figure 5I) and the microcrystal-related matrix mcPs. The mcP is mainly founded in fine-grained packstone and wackestone.…”

“…It indicates the pore size that dominates the sample. 18,21,22 Pores with diameters of larger than 100 μm are macropores, 24 pores with diameters of less than 30 μm are micropores, 56 and others are mesopores.…”

Caracterização de carbonatos bimodais integrando Pressão Capilar por Mercúrio e Ressonância Magnética Nuclear

“…Sabendo-se tratar de textura grainstone, fica evidente que a porosidade entre os grãos (intergranular) é o macroporo com rgp>5 micras e que o microporo (rgp<0,5 micras) só podem estar associados ao grão, ou seja intragranular (dentro dos grãos). Cantrell e Hagerty (1999) discutiram a ocorrência dessa microporosidade em rochas semelhantes na Formação Arab-D. Rahman et al (2012) tratam da classificação de microporosidade em carbonatos apresentando uma breve revisão. Como já foi mostrado na Figura 3, os altos valores de porosidade para amostras com baixa permeabilidade e a dispersão apresentada no gráfico de correlação, sugerem a existência de poros que pouco contribuem para a permeabilidade.…”

Terahertz scattering and water absorption for porosimetry

“…Pores (i.e. the voids), are classified based on their nominal average diameter 'a' to micropores (a<1μm) and macropores (a>1μm), although the threshold diameter may vary based on agreements [8], and field of applications [9]. Flow behavior and micro porosity in porous materials is equally important since it regulates the transport of nutrients and pollutants in soils, and determines the extraction of oil and natural gas from host rocks and geological matrices [10].…”