Waterflood
When should you start waterflood planning?
production rates decline significantly
pressure decline to a low level
economic limit was approaching
What is MMP?
min. pressure at which crude oil will be miscible with CO2 @ reservoir pressure.
What is FCM?
inject a relatively small primary slug that is miscible with oil and followed by a large slug.
Effects of impurities?
methane, nitrogen, and flue gas increase MMP
H2S decreases MMP.
What is infill drilling.
additional wells drilled during primary, secondary, and tertiary field developments.
What is HCPV?
hydrocarbon pore volume
What are MCM processes
vaporizing drive
condensing drive
combined condensing and vaporizing drive
Piston like displacement.
oil flows at initial water saturation ahead of the front and water flows behind like residual oil.
If pressure is below MMP CO2 is more efficient.
True or False
False
What is EOR?
EOR methods modify some physical or chemical properties of rock-fluids systems.
Waterflood pattern assumptions
1. Reservoir is continuous over an area much larger than that on an individual WF pattern.
2. Volumes injected must equal volumes produced.
Advantages of CO2 flooding
1. low solubility with water
2. high solubility with oil
3. low cost and abundance
4. environmental abundance
Why is well spacing so important?
drilling too many wells destroys value; too few wells leaves money on the table.
Supercritical conditions
conditions of temp. and pressure reaching critical point where it exhibits properties of both liquid and gas.
How much does a successful EOR recover?
5 - 20%
WF "rule of thumb"
Plan to inject 10 - 15% HCPV per year
Effects of CO2 solubility
CO2 is more soluble in oil than water
as more CO2 dissolves in the oil, the oil viscosity goes down.
What is slim tube test?
When the same solvent displaces oil at reservoir temperature and above a suitably high pressure in a long, small-diameter (slim) sand packed tube. a miscible-like displacement occurs.
What is Sor?
oil that remains in the reservoir after primary and secondary or tertiary production.
Results from CO2 Fluid swelling
volume of oil increases from 10-40%
water volume does not swell
What's the rule of number of injectors to producers
total number of producers equals or is greater than number of injectors.
Challenges of CO2 flooding
H2S
C1 and N2 impurities
corrosion
poor sweep efficiency
well spacing
What are the functions of MMP correlations?
Temperature and composition
Determining water injection rates
voidage replacement is being controlled by water injection.
miscibility is a function of?
1. temperature
2. reservoir fluid
3. injection gas composition
4. pressure