INTERNATIONAL CONGRESS ON RECENT ADVANCES IN SCIENCES AND TECHNOLOGY - Kuala Lumpur - Malaysia (2019-02-20)

Characteristics of the Nanoscale Pore Structure in the Kroh Formation Using Field Emission Scanning Electron Microscopy and Gas Adsorption
Marine Paleozoic rocks account for about 25% of the surface Peninsular Malaysia. The Paleozoic formations of Peninsular Malaysia are distributed in three northwesterly to northerly trending zones parallel to the general elongation trend of the Peninsula. They are the Western Zone, Central Zone, and Eastern Zone. Each of this zone is characterized by distinctive tectonic, stratigraphy, structure and sedimentary history. Black shales have attracted interest from researchers primarily because of their economic importance in terms of hydrocarbon development potential. During the last few years, considerable attention has been given to unconventional oil and gas shales. Successful exploration and development of shale gas reservoirs have enabled the United States to ensure a predominantly domestic supply of gas for many years. The Kroh Formation is one of the western formations in Peninsular Malaysia, is Upper Ordovician to Lower Devonian age. Generally, the Kroh Formation is composed of black shale, sub-mature arenite, calcareous shale, and limestone. Nevertheless, no work has been carried out in the Kroh Formation related to regards the shale morphology and it is pore structure. Representative samples of black shales from the Kroh Formation were analyzed using Field Emission Scanning Electron Microscope (FE-SEM) occupied with energy dispersive X-ray (EDX) to determine the shapes, sizes, and distributions of pores in shale. Nitrogen adsorption method (N2) using Surface Area Analyzer and Porosimetry System (SAP) was performed to evaluate the nature of the pore structure including, pore size distribution and pore volume. Accurate of the microstructures of the rocks is essential to petroleum engineering for evaluating and development of oil and gas resource. This is especially important for the unconventional reserves with abundant interior nanoscale pores such as shale. The results of SEM-EDX showed that the shale samples mainly composed kaolinite which appears as booklets and quartz as round grains with small oval depressions of various grain sizes. The shale samples have nanoscale pores, which can be classified into four types: inter-particle pores, organic pores, intra-particle pores, and micro-fractures. The abundant of pores in the analysed samples are inter-particle pores between the clay particles and organic nano-pores (Figure 1). The result of N2 adsorption analysis of the shale samples revealed that the pressure adsorption showed significant differences in surface area and pore volumes. The pore size distribution suggested a multi-modal system with a broad peak between 2 nm and 25 nm. The pore volume is predominantly occupied by mesopores (2~ 50 nm), while the main specific surface area is dominated by the micro-pores (< 2 nm) and mesopores (< 50 nm). The porosity of shales proved to be mainly dependant on the degree of pore volume development in pores less than 10nm. Identifying the Characterisation of pore structure is important for estimating Original Gas in Place (OGIP).
Ms. Monera Shoieb