Oil and Gas at Your Door? (2005 Edition) - Earthworks

STAGES OF OIL & GAS DEVELOPMENT
Production Enhancement
A variety of techniques are used to enhance the flow of oil or gas during operations. Some of
these techniques are the same ones used to stimulate flow during well completion, e.g.,
hydraulic fracturing and acidizing.
For enhancement of oil production, a common technique is known as waterflooding. This technique
enhances oil recovery by injecting water to build up the pressure in the reservoir, thus,
forcing more oil into the well.
FIGURE I-17. OIL PRODUCTION ENHANCEMENT USING THE WATERFLOODING TECHNIQUE.
Source: Energy Information Administration, Department of Energy, 1991. 114
Often, produced water is used for the waterflooding operation. Produced water should be thoroughly
treated before injection so that it is free of solids, bacteria, and oxygen, all of which could
contaminate the oil reservoir and, in the case of sulfur-reducing bacteria, could lead to
increased hydrogen sulfide concentrations in the extracted oil. 115
Other methods of enhancement may be used, but are often more expensive and energy intensive
than waterflooding. Examples include: 116
• Thermal recovery, where the reservoir fluid is heated through the injection of steam or by controlled
burning within the reservoir. Heating makes the fluid less viscous and more conducive
to flow. This technique is used to stimulate the flow of heavy oils from oil shales and tar sands.
• The injection of carbon dioxide or alcohol, which reduce oil density, allowing the oil to rise
to the surface more easily.
• The injection of surfactants, which are substances that essentially wash the oil from the
reservoir.
• Microbial enhanced recovery, where oxygen and microbes capable of digesting heavy oil
and asphalt are injected into the formation, freeing up the lighter oil to flow to the surface.
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