Why use N2 for your hydraulic fracturing?
Typically, nitrogen is delivered to the well site as a refrigerated liquid that is gasified prior to injection and then is injected into the well to enhance recovery. As the primary component of the air we breathe, the benefits of nitrogen include it being inert, environmentally friendly, non-flammable, and when gasified, exhibiting very low densities with large expansion factors. These properties make nitrogen the perfect choice for safely and efficiently tackling the toughest well needs.
The use of nitrogen in hydraulic fracturing fluids is very common within the industry. By using nitrogen the liquid portion of the fracturing fluid can be significantly reduced; with less liquid in the treatment and the high mobility and expansion of the nitrogen, the fracturing liquids are much easier and much quicker to remove from the formation. Additionally, the use of nitrogen with water or oil based fracturing fluids can alter the physical properties of the base fluid following the treatment including reducing the viscosity, minimizing relative permeability effects and lowering surface tension. Nitrogen is particularly effective in oil based fracturing fluids where it is benign to the viscosity developing chemicals and exhibits a high but limited solubility. In addition to imparting improved physical properties to the hydrocarbon base fluid, the dissolved nitrogen breaks out of solution during drawdown ensuring a gas phase exists in the pore space and energized flow is achieved. These effects result in improved fracturing fluid mobility within the formation pores, improved recovery of the fracturing fluids and greater production.
Further, replacement of liquids with nitrogen can provide economic and environmental benefit by reducing the liquid volume needed to complete the fracturing treatment. In the case of hydrocarbon based fluids, the nitrogen may be less expensive and provide a cost effective volume substitution thereby lowering the cost of the treatment. Water, though often inexpensive to acquire, may be subject to significant costs for handling and then disposal of the recovered fluid. Consumption of water in the fracturing process and disposal can also have a negative environmental impact. Again nitrogen can provide benefit by reducing the volume of liquids used and then consumed requiring disposal.
Generally fracturing compositions using nitrogen can be distinguished as a mist (a mixture composed of over 95% nitrogen carrying a liquid phase), a foam (a mixture composed of approximately 50% to 95% of nitrogen formed within a continuous liquid phase), or an energized fluid (a mixture composed of approximately 5% to 50% nitrogen).
Oilfield applications of N2
Well drilling and construction:
- Free differentially stuck pipe
- Control drilling fluid losses
- Complete underbalanced drilling
- Reduce cement density with foamed cementing
Completions and workovers:
- Remove liquids from wellbores
- Enhance coiled tubing operations
- Lighten liquid columns in wellbores
Stimulation and hydraulic fracturing:
- Carry treating chemicals deep into formations
- Commingle with acid to improve treatment penetration
- Nitrify fracturing fluids to improve liquids recovery, minimize liquid loading in the wellbore and speed post-fracturing clean-up
- Foam fracturing liquids to improve fracture fluid viscosity and proppant transport
- Effectively fracture coal bed methane wells without reservoir damage
- Substitute nitrogen for water to meet environmental needs
- Substitute nitrogen for workover or fracturing oil to reduce costs
Facilities and pipeline:
- Purge facilities and pipelines for safe turnarounds and repairs
- Safely and effectively pressure test facilities and pipelines
How is liquid nitrogen produced?
Liquid nitrogen is made by Ferus using air that is compressed using electric-driven compressors. After initial compression, trace gases are removed and pressure is released, further cooling the air. This process is repeated until oxygen (O2) turns to liquid and is separated from gaseous nitrogen. The oxygen is then released back into the atmosphere.