Open Access

Downloads

Download data is not yet available.

Abstract

Porosity and permeability play a prerequisite role for hydrocarbon reservoirs and fluid flows, especially in sandstone reservoir rocks. The rocks with high porosity decrease down to lower porosity with increasing burial depth due to compaction, cementation and precipitation of authigenic minerals in pores from over saturated solution of minerals. The detailed study of the authigenic clay mineral formation in pore spaces of sandstone reservoir rocks is therefore crucial to estimate the degree of reservoir rock quality. In this study 20 sandstone cores taken from the interval burial depths of 3,700 m - 4,200 m from Oligocene sandstone sequence of a well in the West of the Cuu Long basin, offshore Vietnam, were analyzed by SEM and thin section. Authigenic clay minerals were formed due to temperature and chemistry changes and owing to dissolution of less stable minerals in these burial depths. Authigenic chlorite mineral appears quite abundantly and illite is less frequently. Chlorite was formed from the elements Al and Si, which were released from dissolved grains and Fe and Mg supplied from breakdown of the ferromagnesian minerals of rock fragments and matrix components into pore waters in the burial stage. Illite is associated with the expense of grain dissolution of feldspar, volcanic fragment. Chlorite mostly appears as a coating or mats comprising of small pseudo-hexagonal crystals arranged perpendicular to detrital grain surfaces. Grainrimming chlorites on quartz grain are responsible for the preservation of the porosity in the sandstones because they limit the formation of quartz overgrowth. Additionally fibrous or flaky illite bridging the pores between the grains creates permeability barriers to fluid flows through the sandstones. Thus illite significantly reduces the permeability but to lesser extent affect porosity. Locally, smectite mixes with illite or chlorite and is not abundant in the studied samples. It therefore has no significant impact on the porosity and permeability as well. The variations of the porosity and the permeability of the studied sandstones depend on the generated degree and the arranged patterns of chlorite and illite in pore spaces.



Author's Affiliation
Article Details

Issue: Vol 17 No 3 (2014)
Page No.: 21-26
Published: Sep 30, 2014
Section: Engineering and Technology - Research article
DOI: https://doi.org/10.32508/stdj.v17i3.1456

 Copyright Info

Creative Commons License

Copyright: The Authors. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

 How to Cite
Ho, T., Lieu, P., Doan, T., & Bui, P. (2014). Generation of authigenic clay minerals during diagenesis and their influences on porosity and permeability of Oligocene sandstone reservoir rocks, from a well in the west of Cuu Long basin. Science and Technology Development Journal, 17(3), 21-26. https://doi.org/https://doi.org/10.32508/stdj.v17i3.1456

 Cited by



Article level Metrics by Paperbuzz/Impactstory
Article level Metrics by Altmetrics

 Article Statistics
HTML = 1564 times
Download PDF   = 562 times
Total   = 562 times