on emaze

water flooding

Secondary oil recovery

water flooding

-Moman Adel

-Mounier Mohammed

Energy demands are increasing around the world. Thus we are slowly heading for oil crisis

By 2030 the oil demands will be 50% higher than now

Increasing demand for oil consumption

Oil recovery

primary

secondary

tertiary

Natural flow / artificial left

water flooding /injection/ gas injection

thermal"steam-hot water" /chemical"polymer-caustic

/gas "co2-nitrogen" /others

What is a Waterflood?

•It is the injection of water into a wellbore to push, or “drive” oil to another well where it can be produced

•Recognized enhanced oil recovery technique since early 1900’s

•Some oil reservoirs have natural water influx, which increases oil production

–Called “water drive” reservoirs

–They are natural “waterfloods”

How does a waterflood work?

•Certain oil wells are converted to water injection wells

•Other oil wells remain as producers

•The injected water displaces, or “pushes” oil to the producing wells

FACTORS TO CONSIDER IN WATERFLOODING

Fluid properties

Reservoir geometry

Reservoir depth

Lithology and rock properties

Fluid saturations

Reservoir uniformity and pay continuity

Primary reservoir driving mechanisms

FLOODING PATTERNS

•The objective is to select the proper pattern that will provide the injection fluid with the maximum possible contact with the crude oil system.

•This selection can be achieved by

1.Converting existing production wells into injectors.

2.drilling infill injection wells.

Factors to determine the reservoir pressure

Water injection should be initiated when the reservoir pressure reaches its bubble-point pressure since the oil viscosity reaches its minimum value at this pressure. The mobility of the oil will increase with decreasing oil viscosity, which in turns improves the sweeping efficiency

Reservoir oil viscosity

EFFECT OF

TRAPPED GAS

First Theory (Cole (1969) )

In this case, this would dictate that the gas molecules enclose themselves in an oil “blanket.” This increases the effective size of any oil globules. The amount of residual oil left in the reservoir would be reduced by the size of the gas bubble within the oil globule.

Second Theory

as water displaced the oil from the reservoir rock, the amount of residual oil left in the larger pore spaces would be reduced because of occupancy of a portion of this space by gas.

two different theories

2-Peripheral

1-Irregular

3-Regular

4-Crestal & basal

Type of arrangments

Peripheral Injection Patterns

•The injection wells are located at the external boundary of the reservoir and the oil is displaced toward the interior of the reservoir.

Regular Injection Patterns

Crestal and Basal Injection Patterns

In crestal injection, as the name implies, the injection is through wells located at the top of the structure. Gas injection projects typically use a crestal injection pattern. In basal injection, the fluid is injected at the bottom of the structure. Many water-injection projects use basal injection patterns with additional benefits being gained from gravity segregation.