Experimental study of chlorite authigenesis and influence on porosity maintenance in sandstones

• DOI: 10.2110/jsr.2020.122
• Publication Date: 2021-03-26T01:49:50Z
• Authors: Dimitrios Charlaftis; Stuart J. Jones; Katherine J. Dobson; Jonathan Crouch; Sanem Acikalin
• Keywords: Authigenic; Cementation (geology)

ABSTRACT Chlorite is recognized as a key mineral for preserving reservoir quality in deeply buried sandstones, chlorite coatings inhibit the nucleation of quartz overgrowths. A limited understanding mechanisms and conditions under which these authigenic form prevents accurate forward modeling diagenesis limits models critical to wide range geoscience applications. We present experimental data that show how grain preserve porosity sandstone reservoirs, using series hydrothermal reactor experiments simulate cementation capture evolving porosity. To evolution, berthierine-bearing samples (Lower Jurassic Cook Formation, Oseberg Field, 30/6-17R, Norway) were exposed silica-supersaturated Na2CO3 (0.1 M) solution 72 hours at temperatures between 100 250 °C. Quantification temperature-dependent changes volume chlorite, thickness coverage clay coatings, sample shows increases (from ∼ 2% 14%). This occurs by transformation, patchy amorphous berthierine into grain-coating Fe-chlorite cements through mixture solid-state transformation dissolution–precipitation mechanisms, siderite replacement, direct precipitation on clay-free surfaces. With increasing temperature, increase from 3.8 μm 5.4 thick expand their surface 28% 50%. The face-to-edge face-to-face foliaceous structure produced are morphologically similar those observed sandstones. Only above 175 °C preserved consequence inhibition overgrowths generation secondary Our quantitative approach enhances our knowledge regarding temperature precursor influence chlorite-coating authigenesis therefore provides insight potential sedimentary sequences greater than 2.5 km.