Kerogen is usually classified into one of three types, based on bulk H/C and O/C ratios
Type I kerogen has a high H/C (atomic) ratio (>1.5) and a low O/C (atomic) ratio (<0.1). It is rich in lipids, especially long-chain aliphatics, and has high petroleum potential. It is derived primarily from algal and bacterial remains, often deposited in aquatic or estuarine environments.
Type II kerogen, the most common type, has intermediate H/C (~ 1.25) and O/C (<2.0) ratios. It is derived primarily from planktonic and bacterial remains deposited in marine environments (though remains of high plants can contribute as well). Because of its marine origin, it is often sulfur rich. Its lipid content and oil potential are somewhat lower than Type I kerogen.
Type III kerogen has low H/C ratios (<1.0) and high O/C ratios (<0.3). It is rich in aromatic and poor in aliphatic structures. It is formed principally from the remains of vascular plants. Its oil potential is poor, but can be a source of gas (particularly methane).
No comments:
Post a Comment