Geoscience Reference
In-Depth Information
Flowing and pumped wells are considered “primary recovery” from the well and about
12 to 20 percent of the original oil in place in the reservoir is recovered in this manner.
This relatively low rate of recovery results from several factors: (1) the decrease in natural
reservoir pore pressure over time; (2) the natural porosity and permeability of the rock
formation (which is an indication of how easily the oil can move through the formation to
the well bore); and (3) the viscosity of the oil, which, when combined with porosity and
permeability, is also an indicator of the ease with which oil can migrate through the rock.
Recovery rates for natural gas are generally higher than for oil (up to 50 to 80 percent may
be recovered through primary production methods) because gas expands naturally upon
release of pressure and has a lower viscosity than liquid petroleum, contributing to the
natural movement of gas up the well bore (Shepherd, 2009).
When primary recovery is no longer viable, petroleum companies may use a variety
of technologies to extract the remaining oil and gas. These technologies include what are
termed secondary and tertiary recovery methods; tertiary recovery is generally also referred
to as enhanced oil recovery (EOR) (Shepherd, 2009). Figure 3.8 shows the differences
between primary, secondary, and tertiary recovery methods.
PrimaryﾠRecoveryﾠ
OilﾠRecoveryﾠ
Generallyﾠlessﾠﾠ
thanﾠ30%ﾠ
NaturalﾠFlowﾠ
Ar.ficialﾠLi2ﾠ
SecondaryﾠRecoveryﾠ
30‐50%ﾠ
Waterfloodingﾠﾠ
PressureﾠMaintenanceﾠ
>50%ﾠandﾠ
upﾠtoﾠ80+%ﾠ
Ter.aryﾠRecoveryﾠ
Thermalﾠ
GasﾠInjec.onﾠ
Chemicalﾠ
Otherﾠ
Alkaliﾠ
Surfactantﾠ
Polymerﾠ
Steamﾠ
HotﾠWaterﾠ
Combus.onﾠ
CO
2ﾠ
Hydrocarbonﾠ
Nitrogen/Flueﾠ
Microbialﾠ
Acous.cﾠ
Electromagne.cﾠ
FIGURE 3.8
Schematic showing the progression of oil production from primary to tertiary recovery. IOR,
improved oil recovery; EOR, enhanced oil recovery. SOURCE: Al-Mutairi and Kokal (2011).
Search WWH ::
Custom Search