− | The shale smear factor remains constant between the offset terminations because it does not depend on smear distance (although lateral variations in fault throw would have a corresponding effect on the calculated SSF). SSF thus models the profile of abrasion-type smears. From a study of 80 faults (excluding composite smears), Lindsay et al.<ref name=Lindsay /> concluded that shale smears may become incomplete for an SSF greater than 7. Smaller values of SSF are more likely to correspond to continuous smears and therefore to a sealing layer on the fault surface. The values of SSF are not additive for compound smears because thin shales give higher SSF and dominate the sum. In such cases, a simple application of SSF values would take the minimum value (most sealing) from the relevant shale beds at that point on the fault. | + | The shale smear factor remains constant between the [[offset]] terminations because it does not depend on smear distance (although [[lateral]] variations in fault throw would have a corresponding effect on the calculated SSF). SSF thus models the profile of abrasion-type smears. From a study of 80 faults (excluding composite smears), Lindsay et al.<ref name=Lindsay /> concluded that shale smears may become incomplete for an SSF greater than 7. Smaller values of SSF are more likely to correspond to continuous smears and therefore to a sealing layer on the fault surface. The values of SSF are not additive for compound smears because thin shales give higher SSF and dominate the sum. In such cases, a simple application of SSF values would take the minimum value (most sealing) from the relevant shale beds at that point on the fault. |
| [[File:Shale-smear-factor-fig2.png|center|{{figure number|1}}Smear factor algorithms for estimating likelihood of clay smear on a fault plane. (a) Clay smear potential (CSP)<ref>Bouvier, J. D., C. H. Kaars-Sijpesteijn, D. F. Kluesner, C. C. Onyejekwe, and R. C. Van der Pal, 1989, [http://archives.datapages.com/data/bulletns/1988-89/data/pg/0073/0011/1350/1397.htm Three-dimensional seismic interpretation and fault sealing investigations, Nun River field, Nigeria]: AAPG Bulletin, v. 73, p. 1397-1414.</ref><ref>Fulljames, J. R., L. J. J. Zijerveld, R. C. M. W. Franssen, G. M. Ingram, and P. D. Richard, 1996, Fault seal processes, in Norwegian Petroleum Society, eds., Hydrocarbon seals-importance for exploration and production (conference abstracts): Oslo, Norwegian Petroleum Society, p. 5.</ref> given by the square of source-bed thickness divided by smear distance; (b) generalized smear factor, given by source-bed thickness divided by smear distance, with variable exponents; (c) shale smear factor (SSF)<ref name=Lindsay /> given by fault throw divided by source-bed thickness. Methods (a) and (b) model the distance-tapering of shear-type smears, whereas method (c) models the form of abrasion smears.]] | | [[File:Shale-smear-factor-fig2.png|center|{{figure number|1}}Smear factor algorithms for estimating likelihood of clay smear on a fault plane. (a) Clay smear potential (CSP)<ref>Bouvier, J. D., C. H. Kaars-Sijpesteijn, D. F. Kluesner, C. C. Onyejekwe, and R. C. Van der Pal, 1989, [http://archives.datapages.com/data/bulletns/1988-89/data/pg/0073/0011/1350/1397.htm Three-dimensional seismic interpretation and fault sealing investigations, Nun River field, Nigeria]: AAPG Bulletin, v. 73, p. 1397-1414.</ref><ref>Fulljames, J. R., L. J. J. Zijerveld, R. C. M. W. Franssen, G. M. Ingram, and P. D. Richard, 1996, Fault seal processes, in Norwegian Petroleum Society, eds., Hydrocarbon seals-importance for exploration and production (conference abstracts): Oslo, Norwegian Petroleum Society, p. 5.</ref> given by the square of source-bed thickness divided by smear distance; (b) generalized smear factor, given by source-bed thickness divided by smear distance, with variable exponents; (c) shale smear factor (SSF)<ref name=Lindsay /> given by fault throw divided by source-bed thickness. Methods (a) and (b) model the distance-tapering of shear-type smears, whereas method (c) models the form of abrasion smears.]] |