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Energized Fracturing of Oil & Gas Wells
A Sustainable Approach to Higher Reservoir YieldsWhether waterless or as part of a foam, using carbon dioxide or nitrogen offers many benefits over traditional fracturing methods
Why Use Energized Solutions?
Fracturing with carbon dioxide or nitrogen allows developers to expand beyond conventional oil and gas reserves to also develop partially depleted reserves and unconventional deposits. Well fracturing thus has the ability to contribute to energy security.
The flexibility of energized solutions allows for the hydraulic fracturing fluid to be mixed according to the technological needs of each reservoir. They provide more rapid and complete treatment fluid recovery, help to clean without swabbing, and reduce formation damage by lowering the amount of aqueous fluids introduced into the formation. In addition, energized solutions can enhance proppant-transport properties and, in the case of under-pressured or depleted zones, provide enhanced energy for hydrocarbon recovery.
Lowering Formation Damage
Proppant can cause damage. Too little, too much, improperly placed or of poor quality, and it can block the flow of oil and gas. Fractures too far apart, too close together or that tap into non-productive areas of the reservoir can create damage. Residue left from polymers and gels used in fracturing can impede flow through the proppant pack, while overflushing to remove the residue can create fines - superfine particles that can block the flow as they migrate. Leak-off, both a reservoir and treatment fluid property, in aqueous or liquid form can also block flow. Liquid leak-off causes water saturation to increase, thereby decreasing the relative permeability to gas, and may play a significant role in damage to gas reservoirs.
Energized solutions, however, use less water than conventional fracturing treatments and provide energy for the recovery of induced fluids while decreasing the fluid leak-off potential, thus lowering the risk of reservoir damage. Less water means less potential for clay swelling, fines migration and fluid retention. Less damage enhances flow for effective flowback, thus reducing the time it takes to move into production while increasing overall productivity.
Benefits of Fracturing with CO2 Foam
Used extensively since 1962 as an additive to acid fracturing, carbon dioxide (CO2) is very soluble with oil and water. Due to this high solubility, it greatly reduces viscosity during a fracturing treatment. This provides greater opportunities to energize the flow of more viscous hydrocarbons, especially oil.
In formations where clays are usually found, using CO2 with the frac fluid lowers the swelling of these clays due to its low pH, allowing the sand-laden fluid to penetrate further into the fractures. A lower volume of pumped gel means less unbroken gel left in the rock pore space and less on the fracture walls.
Far less water is introduced into the formation compared with traditional frac treatments. This results in significantly less liquid to clean up and less liquid trapped in the formation by capillary forces. Additionally, the high percentage of CO2 lightens the fluid column in the well bore, reducing the energy required to remove the frac fluids. As it expands, CO2 also provides much of the energy needed to remove the fracture fluids and excess sand. This results in faster, more thorough, and more economical cleanup as well as accelerated well production startup.
No Special Equipment Required
The use of CO2 can be an added advantage for service companies and well operators because the same equipment as that used for water - with very limited modifications - can be used to pump the high-pressure CO2.
Safety is our Priority
As a non-flammable frac fluid, CO2 is a sustainable alternative to other waterless fracturing fluids such as propane/butane or diesel fuel. We have safely provided CO2 pumping services for oil and gas and mining applications since the late 1970s. With over 40 years of experience supplying industrial gases to well sites, and with a far-reaching CO2 supply network, we are a trusted CO2 supplier for oil and gas extraction use cases.
Benefits of Fracturing with N2 Foam
Like carbon dioxide (CO2), nitrogen (N2) can be used alone or mixed with other components for fracturing oil and gas wells. It has the added advantage of being typically more readily available for unconventional reservoir plays. It can be injected into the well in pure form as a gas or as a foam. It works effectively without proppant in formations where the rock effectively props itself. For liquid-free stimulations, it can be ideal for fracturing dry, shallow formations, such as coalbed methane (CBM). Though less soluble than CO2, N2 can establish presence in the invaded zone with additional measures, such as delaying flowback to allow the gas phase to penetrate. Because it is an energized treatment, N2 improves reservoir flow, providing trapped hydrocarbons with a lift. It also reduces leak-off while improving fracturing fluid recovery.