Changes

  | part    = Predicting the occurrence of oil and gas traps

  | part    = Predicting the occurrence of oil and gas traps

  | chapter = Predicting preservation and destruction of accumulations

  | chapter = Predicting preservation and destruction of accumulations

  | frompg  = 11-1

  | frompg  = 11-13

  | topg    = 11-30

  | topg    = 11-14

  | author  = Alton A. Brown

  | author  = Alton A. Brown

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch11/ch11.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch11/ch11.htm

==Seal failure mechanisms==

==Seal failure mechanisms==

A given seal can leak by one of several mechanisms, as defined by Watts.<ref name=ch11r38>Watts, N., L., 1987, Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns: Marine and Petroleum Geology, vol. 4, p. 274–307., 10., 1016/0264-8172(87)90008-0</ref> The first three mechanisms listed have minimum pressure criteria to be exceeded before leakage occurs. Even after leakage, an economic column of petroleum may remain. The last two mechanisms can destroy an accumulation, given enough time. Follow the links for more details:

A given seal can leak by one of several mechanisms, as defined by Watts.<ref name=ch11r38>Watts, N., L., 1987, Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns: Marine and Petroleum Geology, vol. 4, p. 274–307., 10., 1016/0264-8172(87)90008-0</ref> The first three mechanisms listed have minimum pressure criteria to be exceeded before leakage occurs. Even after leakage, an economic column of petroleum may remain. The last two mechanisms can destroy an [[accumulation]], given enough time. Follow the links for more details:

{| class = "wikitable"

{| class = "wikitable"

|-

|-

| [[Intact membrane seal leakage|Intact membrane]]

| [[Intact membrane seal leakage|Intact membrane]]

| [[Capillary pressure]] (created by the height of the underlying petroleum column) exceeds seal capillary displacement pressure. This seal type does not fracture during deformation.

| [[Capillary pressure]] (created by the height of the underlying petroleum column) exceeds [[Top seal displacement pressure|seal capillary displacement pressure]]. This seal type does not [[fracture]] during [[deformation]].

|-

|-

| [[Fractured membrane seal leakage|Fractured membrane]]

| [[Fractured membrane seal leakage|Fractured membrane]]

| Capillary pressure  exceeds displacement pressure of fracture [[porosity]] in the seal.

| Capillary pressure  exceeds [[displacement pressure]] of fracture [[porosity]] in the seal.

|-

|-

| [[Hydrofractured seal leakage|Hydrofractured]]

| [[Hydrofractured seal leakage|Hydrofractured]]

| Total fluid pressure ([[capillary pressure]] plus water pressure) exceeds minimum compressive stress of the seal; seal fails by natural hydraulic fracturing.

| Total fluid pressure ([[capillary pressure]] plus water pressure) exceeds minimum compressive [[Wikipedia:Stress (mechanics)|stress]] of the seal; seal fails by [[Natural hydraulic fracturing of top seals|natural hydraulic fracturing]].

|-

|-

| [[Micropermeable seal leakage|Micropermeability]]

| [[Micropermeable seal leakage|Micropermeability]]

| Leakage is caused by low displacement pressures of [[Seal capacity of breached and hydrocarbon-wet seals|oil-wet seals]] or by capillary pressure of the reservoir exceeding displacement pressure of the seal in a water-wet seal. Accumulations are preserved for geologically significant time if leakage rate is low. Rate of leakage is controlled by seal effective [[permeability]].

| Leakage is caused by low displacement pressures of [[Seal capacity of breached and hydrocarbon-wet seals|oil-wet seals]] or by capillary pressure of the reservoir exceeding displacement pressure of the seal in a water-wet seal. [[Accumulation]]s are preserved for geologically significant time if leakage rate is low. Rate of leakage is controlled by seal effective [[permeability]].

|-

|-

| [[Diffusive seal leakage|Diffusive]]

| [[Diffusive seal leakage|Diffusive]]

==See also==

==See also==

* [[Predicting overall seal failure]]

* [[Seal failure prediction]]

* [[Trap spillage]]

* [[Trap spillage]]

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting preservation and destruction of accumulations]]

[[Category:Predicting preservation and destruction of accumulations]]