Changes

===Semipermeable fluid barriers===

===Semipermeable fluid barriers===

Semipermeable barriers can divide a reservoir into compartments with different fluid contacts even if the capillary properties of the reservoir rock are the same on both sides of the barrier. Semipermeable barriers can include faults, mineralized fractures, or semipermeable beds. The resulting pool has horizontal fluid contacts, but the contacts occur at different elevations on different sides of the barrier ([[:file:fluid-contacts_fig5.png|Figure 5]]). The elevation difference between fluid contacts is related to the [[displacement pressure]] of the semipermeable barrier.<ref name=pt06r151>Watts, N. L., 1987, Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns: Marine and Petroleum Geology, v. 4, p. 274–307, DOI: [http://www.sciencedirect.com/science/article/pii/0264817287900080 10.1016/0264-8172(87)90008-0].</ref> Whereas fault or mineralized fracture compartmentalization is not readily recognized without detailed mapping, semipermeable beds are commonly recognized and the reservoir is separated into different pools corresponding to the different fluid contacts. Once the position of the barrier is mapped and the elevations of the contact on either side are determined from control wells, the fluid contacts can be mapped as horizontal surfaces within each compartment of the pool. Limited communication across semipermeable barriers is possible during production from the pool.

Semipermeable barriers can divide a reservoir into compartments with different fluid contacts even if the [[Capillary pressure|capillary properties]] of the reservoir rock are the same on both sides of the barrier. Semipermeable barriers can include [[fault]]s, mineralized [[fracture]]s, or semipermeable beds. The resulting pool has horizontal fluid contacts, but the contacts occur at different elevations on different sides of the barrier ([[:file:fluid-contacts_fig5.png|Figure 5]]). The elevation difference between fluid contacts is related to the [[displacement pressure]] of the semipermeable barrier.<ref name=pt06r151>Watts, N. L., 1987, Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns: Marine and Petroleum Geology, v. 4, p. 274–307, DOI: [http://www.sciencedirect.com/science/article/pii/0264817287900080 10.1016/0264-8172(87)90008-0].</ref> Whereas fault or mineralized fracture compartmentalization is not readily recognized without detailed mapping, semipermeable beds are commonly recognized and the reservoir is separated into different pools corresponding to the different fluid contacts. Once the position of the barrier is mapped and the elevations of the contact on either side are determined from control wells, the fluid contacts can be mapped as horizontal surfaces within each compartment of the pool. Limited communication across semipermeable barriers is possible during production from the pool.

==Anomalously thick transition zones==

==Anomalously thick transition zones==