− | Studies of the [[hydrocarbon distribution]] in the Gulf Coast relative to the top of overpressure suggest hydraulic fracturing and seal integrity influence the vertical distribution of hydrocarbons, success ratios, and seal risk.<ref name=ch10r30>Fertl, W., H., Leach, W., G., 1988, Economics of hydrocarbon reserves in overpressured reservoirs below 18,000 feet in south Louisiana: SPE paper 18146, 16 p.</ref><ref name=ch10r46>Leach, W., G., 1993a, Fluid [[migration]], HC concentration in south Louisiana Tertiary sands: Oil & Gas Journal, vol. 91, no. 11, p. 71–74.</ref><ref name=ch10r47>Leach, W., G., 1993b, Maximum hydrocarbon window determination in south Louisiana: Oil & Gas Journal, vol. 91, no. 13, p. 81–84.</ref> | + | Studies of the [[hydrocarbon distribution]] in the Gulf Coast relative to the top of overpressure suggest [[Natural hydraulic fracturing of top seals|hydraulic fracturing]] and seal integrity influence the vertical distribution of hydrocarbons, success ratios, and seal risk.<ref name=ch10r30>Fertl, W., H., Leach, W., G., 1988, Economics of hydrocarbon reserves in overpressured reservoirs below 18,000 feet in south Louisiana: SPE paper 18146, 16 p.</ref><ref name=ch10r46>Leach, W., G., 1993a, Fluid [[migration]], HC concentration in south Louisiana Tertiary sands: Oil & Gas Journal, vol. 91, no. 11, p. 71–74.</ref><ref name=ch10r47>Leach, W., G., 1993b, Maximum hydrocarbon window determination in south Louisiana: Oil & Gas Journal, vol. 91, no. 13, p. 81–84.</ref> |
− | The distribution of hydrocarbons relative to the top of overpressure changes as reservoir depth changes is shown in [[:file:evaluating-top-and-fault-seal_fig10-46.png|Figure 2]]. This pattern is consistent with loss of top seal integrity because of hydrofracturing rather than a simple loss of reservoir quality or other variable. Deeper reservoirs have the peak gas occurrence below the top of overpressure. This is consistent with the changing P<sub>f</sub> with depth. As depth increases, confining pressure increases and thus the amount of pressure required to fracture the top seal (P<sub>f</sub>) increases. As fracture pressure increases, the depth of the first intact top seal increases. | + | The distribution of hydrocarbons relative to the top of overpressure changes as reservoir depth changes is shown in [[:file:evaluating-top-and-fault-seal_fig10-46.png|Figure 2]]. This pattern is consistent with loss of top seal integrity because of [[Natural hydraulic fracturing of top seals|hydrofracturing]] rather than a simple loss of reservoir quality or other variable. Deeper reservoirs have the peak gas occurrence below the top of overpressure. This is consistent with the changing P<sub>f</sub> with depth. As depth increases, confining pressure increases and thus the amount of pressure required to fracture the top seal (P<sub>f</sub>) increases. As fracture pressure increases, the depth of the first intact top seal increases. |