2,803
edits
Changes
Jump to navigation
Jump to search
Line 47:
Line 47: − +
→Capillary pressure concepts
These equations show that capillary pressure increases with greater height above the free surface and with smaller capillary size.
These equations show that capillary pressure increases with greater height above the free surface and with smaller capillary size.
The importance of capillary pressure in reservoir studies is that many reservoir rocks can be approximated by a bundle of capillaries, with formation water being the wetting phase and hydrocarbons the nonwetting phase. As hydrocarbons begin to migrate into a rock, displacing the pore water, the hydrocarbons first enter the pores with the largest pore throats (capillaries), leaving the wetting phase (water) in the pores with smaller throats or in small nooks and crannies (surface roughness). As the hydrocarbon column increases, the height above the surface where ''P''<sub>c</sub> = 0, called the free surface or ''free water level'' (FWL), becomes greater and the capillary pressure increases, allowing hydrocarbons to enter pores with smaller and smaller throats. This process continues ntil one of several things occurs:
The importance of capillary pressure in reservoir studies is that many reservoir rocks can be approximated by a bundle of capillaries, with formation water being the wetting phase and hydrocarbons the nonwetting phase. As hydrocarbons begin to migrate into a rock, displacing the pore water, the hydrocarbons first enter the pores with the largest pore throats (capillaries), leaving the wetting phase (water) in the pores with smaller throats or in small nooks and crannies (surface roughness). As the hydrocarbon column increases, the height above the surface where ''P''<sub>c</sub> = 0, called the free surface or ''free water level'' (FWL), becomes greater and the capillary pressure increases, allowing hydrocarbons to enter pores with smaller and smaller throats. This process continues until one of several things occurs:
# generation or migration ends,
# generation or migration ends,
# the trap reaches its spill point, or
# the trap reaches its spill point, or