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Line 17: − An FPLP is a type of fault-dependent leak point in which the hydrocarbon contact coincides with the intersection of the fault plane and the top of the reservoir. As shown in the following figure, an FPLP limits the hydrocarbon to the structurally independent closure. The lack of hydrocarbons in contact with the fault plane implies leakage has occurred vertically along the fault.<ref name=ch10r76>Smith, D., A., 1966, Theoretical considerations of sealing and non-sealing faults: AAPG Bulletin, vol. 50, no. 2, p. 363–374.</ref><ref name=ch10r3>Allard, D., M., 1993, Fault leak controlled trap fill, rift basin examples (abs.), in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg conference, Crested Butte, Colorado, June 21–23.</ref><ref name=ch10r34>Harding, T., P., Tuminas, A., C., 1988, Interpretation of footwall (lowside) fault traps sealed by reverse faults and convergent wrench faults: AAPG Bulletin, vol. 72, no. 7, p. 738–757.</ref> − + + + Line 27:
Line 28: − An example of asymmetric dip leakage is the Chocolate Bayou field, U.S. Gulf Coast, shown in the following figure. All of the hanging wall gas accumulations are limited by FPLPs and dip leak. The three gas accumulations in the footwall, however, are all dip sealing; all have gas columns in contact with the fault plane. This pattern of behavior is common in both the U.S. Gulf Coast and the Niger Delta.<ref name=ch10r93 /> − + + + + + − + − + − + − − [[file:evaluating-top-and-fault-seal_fig10-13.png|thumb|{{figure number|10-13}}See text for explanation.]]
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==Fault plane leak point (FPLP)==
==Fault plane leak point (FPLP)==
[[file:evaluating-top-and-fault-seal_fig10-10.png|thumb|{{figure number|10-10}}See text for explanation.]]
[[file:evaluating-top-and-fault-seal_fig10-10.png|thumb|{{figure number|1}}See text for explanation.]]
An FPLP is a type of fault-dependent leak point in which the hydrocarbon contact coincides with the intersection of the fault plane and the top of the reservoir. As shown in [[:[file:evaluating-top-and-fault-seal_fig10-10.png|Figure 1]], an FPLP limits the hydrocarbon to the structurally independent closure. The lack of hydrocarbons in contact with the fault plane implies leakage has occurred vertically along the fault.<ref name=ch10r76>Smith, D., A., 1966, Theoretical considerations of sealing and non-sealing faults: AAPG Bulletin, vol. 50, no. 2, p. 363–374.</ref><ref name=ch10r3>Allard, D., M., 1993, Fault leak controlled trap fill, rift basin examples (abs.), in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg conference, Crested Butte, Colorado, June 21–23.</ref><ref name=ch10r34>Harding, T., P., Tuminas, A., C., 1988, Interpretation of footwall (lowside) fault traps sealed by reverse faults and convergent wrench faults: AAPG Bulletin, vol. 72, no. 7, p. 738–757.</ref>
The ability to predict leakage is important in prospect assessment. An FPLP limits the hydrocarbon volume. Where no independent closure exists, prospects may be completely emptied by dip leakage.
The ability to predict leakage is important in prospect assessment. An FPLP limits the hydrocarbon volume. Where no independent closure exists, prospects may be completely emptied by dip leakage.
==Example of asymmetric dip leakage==
==Example of asymmetric dip leakage==
[[file:evaluating-top-and-fault-seal_fig10-11.png|thumb|{{figure number|10-11}}After .<ref name=ch10r57>Myers, J., D., 1968, Differential pressures: a trapping mechanism in Gulf Coast oil and gas fields: Gulf Coast Assoc. of Geologists Transactions, vol. 18, p. 56–80.</ref> Copyright: Gulf Coast Assoc. of Geologists.]]
[[file:evaluating-top-and-fault-seal_fig10-11.png|thumb|{{figure number|2}}After .<ref name=ch10r57>Myers, J., D., 1968, Differential pressures: a trapping mechanism in Gulf Coast oil and gas fields: Gulf Coast Assoc. of Geologists Transactions, vol. 18, p. 56–80.</ref> Copyright: Gulf Coast Assoc. of Geologists.]]
An example of asymmetric dip leakage is the Chocolate Bayou field, U.S. Gulf Coast, shown in [[:file:evaluating-top-and-fault-seal_fig10-11.png|Figure 2]]. All of the hanging wall gas accumulations are limited by FPLPs and dip leak. The three gas accumulations in the footwall, however, are all dip sealing; all have gas columns in contact with the fault plane. This pattern of behavior is common in both the U.S. Gulf Coast and the Niger Delta.<ref name=ch10r93 />
[[file:evaluating-top-and-fault-seal_fig10-12.png|thumb|{{figure number|3}}See text for explanation.]]
==Low-side traps==
==Low-side traps==
Low-side traps may have very different fault seal risk compared with high-side traps. In the following figure, a map shows that dip leakage in the hanging wall limits fill (shaded) to the structurally independent closure. Dip seal in the footwall allows fill in excess of the independent closure. The footwall contains purely fault-dependent traps. The hanging wall relies upon independent closure for entrapment.
Low-side traps may have very different fault seal risk compared with high-side traps. In [[:file:evaluating-top-and-fault-seal_fig10-12.png|Figure 3]], a map shows that dip leakage in the hanging wall limits fill (shaded) to the structurally independent closure. Dip seal in the footwall allows fill in excess of the independent closure. The footwall contains purely fault-dependent traps. The hanging wall relies upon independent closure for entrapment.
[[file:evaluating-top-and-fault-seal_fig10-12.png|thumb|{{figure number|10-12}}See text for explanation.]]
[[file:evaluating-top-and-fault-seal_fig10-13.png|thumb|{{figure number|4}}See text for explanation.]]
==Dip leakage of gas vs. oil==
==Dip leakage of gas vs. oil==
Afault may dip seal oil and dip leak gas or vice versa. The following illustration shows a fault that is dip leaking to gas in both the hanging wall and footwall. Both gas accumulations are limited by an FPLP. The oil accumulation in the footwall, however, is filled beyond the structurally independent closure. The fault is dip sealing to oil but dip leaking to gas.
Afault may dip seal oil and dip leak gas or vice versa. The illustration in [[:file:evaluating-top-and-fault-seal_fig10-13.png|Figure 4]] shows a fault that is dip leaking to gas in both the hanging wall and footwall. Both gas accumulations are limited by an FPLP. The oil accumulation in the footwall, however, is filled beyond the structurally independent closure. The fault is dip sealing to oil but dip leaking to gas.
==Direction of dip leakage==
==Direction of dip leakage==