Disclosed is an improvement to water-alternating-gas (WAG) processes for oil recovery that utilizes an enzyme detergent additive to increase the ability of the water phase to change the adhesion behavior of hydrocarbons to recover and mobilize oil. GreenZyme® is non-reactive and can be used with to miscible and immiscible gases processes.
In an overview, the water-alternating-gas (WAG) and enzyme system (EEOR) is comprised of four (4) stages. The first stage includes a normal water composition injection stage; an alternative period of idle process known as the soak stage; followed by the gas injection stage; finally the recovery stage of produced oil by one or more producing wells. This WAG and enzyme system is sequential and repeated based on the economics and availability of gas to inject, water availability, energy requirements to both produce oil, recover and re-inject the gas, and increased production and recovery rates achieved.
During the regular water injection stage, GreenZyme® is added to water where it is then pumped down an injection pipe, and displaced into the producing formation rock to interact with the fluids. The use of GreenZyme will improve the permeation of oil in the formation via the creation of smart water using enzyme fluid technology.
The water composition acts to release the oil from solid surfaces, increase the mobility of the oil by reducing surface tension, decreasing contact angles, preventing crude oil
that has become less viscous from re-adhering to itself and acts catalytically in contacting and releasing oil from solid surfaces.
Blockages in the oil well formation may be reduced or eliminated as well. The enzymes are pushed into the oil well formation to further contact oil particles thereby increasing contact volume and liberation activity.
The soak stage allows the water and enzyme solution to permeate the oil well formation allowing the enzymes to reach maximum oil releasing efficiency. It is not restricted by variations in the (API) specific gravity ratings of the crude oil. Using WAG, the soak stage lasts between 0-30 days depending on the type and size of the oil well formation. Normally following the soak stage there is a gas injection stage to which a gas injection pump is connected to the oil well formation. Miscible, near miscible or immiscible gas under pressure flows into the oil well formation to make contact with GreenZyme.
The gas then displaces the enzyme-water solution while simultaneously pushing oil particles toward the formation where recovery operations occur. This effects mitigates fingering by changing the attachment behavior of crude. GreenZyme will also have positive effects on displacing water conning zones.
Following the gas injection stage is the final recovery stage in which one or more producing wells are connected to the oil well formation via a retrieval pipe.
Enzyme Enhanced Oil Recovery (EEOR) for water alternating gas (WAG) systems
Application number: 20080142230, Issued: June 19, 2008