A simple analysis of oil-induced fracturing in sedimentary rocks |
| |
| Institution: | 1. School of Natural and Built Environment, Queen''s University Belfast, Belfast BT7 1NN, Northern Ireland, UK;2. Department of Earth and Environmental Sciences, Geology Division, University of Leuven, Celestijnenlaan 200E, 3001 Leuven-Heverlee, Belgium;3. Geological Survey of Northern Ireland, Dundonald House, Upper Newtownards Road, Belfast BT4 3SB, Northern Ireland, UK;1. Computational Earth Science (EES-16), Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA;2. Earth System Observations (EES-14), Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA;3. Geophysics (EES-17), Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA |
| |
| Abstract: | Geometric form of kerogen patches control oil-induced fracturing in impermeable source rocks. Thin elongate kerogen flakes cause lateral fracturing. Kerogen has to occur in spherical or cylindrical forms to induce vertical fractures. If length to width ratio of kerogen flakes is sufficiently large, then lateral fractures are definitely initiated during oil generation in impermeable source rock. Oil and rock compressibilities, and lateral to vertical stress ratio are decisive factors in vertical fracturing in impermeable rocks. Lateral to vertical stress ratio is generally higher than the maximum for oil-induced vertical fracturing in tectonically relaxed sedimentary basins. Oil generation cannot initiate vertical fractures, except when the lateral to vertical stress ratio is reduced below critical level either by tectonic tension or erosion of overburden.When the source rock is permeable, then the rate of oil seepage from kerogen into the surrounding rock is crucial in fracture initiation. Oil-induced fractures cannot form unless permeability, and hence rate of oil seepage from kerogen into the surrounding rock, is non-existent or negligible. Most source rocks have some permeability. Therefore, oil-induced fracture initiation should be a rare phenomenon. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
