Reservoir Efficiency Processes – Various Programs of the D.O.E. – part two
Polymer Flooding: In this enhanced water-flooding method, high molecular weight water-soluble polymers are added to the injection water to improve its mobility ratio, reducing oil "bypassing" and raising yields.
Permeability profile modification treatments with polymer solutions are becoming increasingly common. Incremental production cost is estimated at $5 to $10 per barrel.
Surfactant Flooding: Also known as mi-cellar-polymer flooding, low-tension water-flooding, and micro-emulsion flooding, this method typically involves injecting a small slug of surfactant solution into the reservoir, followed by polymer-thickened water, and then brine.
Despite its very high displacement efficiency, mi-cellar-polymer flooding is hampered by the high cost of chemicals and excessive chemical losses within the reservoir. Incremental production cost is estimated at $8 to $12 per barrel.
One of the key projects in this area is with Lawrence Berkeley National Laboratory (LBNL). The Laboratory is investigating effective surfactant packages and a mechanism- based simulator of foam displacement in porous media for mobility control in improved oil recovery processes.
Although modern improved oil recovery practice is well developed in the area of dislodging trapped oil, mobility control is not well-developed, even though the basic principles are understood. Because reservoirs are naturally heterogeneous, all current enhanced oil recovery processes (including steam flooding, hydrocarbon injection, carbon dioxide flooding, alkaline flooding, and surfactant flooding) require mobility control.
This work focuses on the use of gas-aqueous surfactant dispersions as a general mobility control agent, both in establishing macroscopic sweep efficiency and microscopic displacement efficiency, and are under development for a range of enhanced oil recovery processes. Foams are under development for both in-depth sweep improvement and local well profile modification.
This method takes advantage of microbial byproducts in the reservoir, such as carbon dioxide, methane, polymer, alcohol, acetone, and other compounds. These, in turn, can change oil properties in a positive direction, and thereby facilitate additional oil recovery.
This method is usually applicable to marginal oil wells in the well stimulation mode. Incremental production cost is estimated at $1 to $8 per barrel.
Idaho National Engineering and Environmental Laboratory (INEEL) is currently developing and field testing improved, more cost effective, and environmentally acceptable methods of oil recovery using microbial enhanced oil recovery (MEOR) technology.
This research involves production and application of microbially produced polymers and biosurfactants produced from agricultural wastes; elucidation and quantification of microbial mechanisms responsible for oil displacements; and development of microbial systems for oil recovery and application of MEOR systems in industry cost-shared field demonstrations.
MEOR research has progressed rapidly in the past few years, but improved understanding of the controlling mechanisms and economics of MEOR processes are required before this technology will be a viable method for general application.
Note: One-Dimensional Reservoir Simulation
Researchers at the Department of Petroleum Engineering at Stanford University, funded by DOE and a consortium of oil companies, have developed a novel computational technique that greatly improves current state-of-the-art reservoir simulation technology.
Basically, fluid flow in a reservoir is calculated in one dimension, but also separately along many "streamlines."
This one-dimensional simulation technology is 1,000 times faster than conventional reservoir simulation, and is more accurate as well (even for very complex production scenarios). Such accelerations in the time needed to complete simulations will allow a much more extensive search for optimal production strategies.
Source: United States Department of Energy