Slurry fracture injection is a process by which solid particulate wastes may be combined with waste fluids and injected at fracturing conditions into the deep subsurface for disposal. It holds a number of significant environmental advantages over traditional landfill disposal, and has been applied with increasing success for large volume waste disposal in the oil and gas industry. This technology has also been recently applied to dispose of municipal sanitation wastes. The natural geothermal heat present in the deep subsurface biodegrades the organic waste, converting it into CO2 and CH4. The CO2 is preferentially dissolved and sequestered in the native formation fluids, while methane in relatively pure form collects for potential recovery as a source of renewable energy.
Slurry fracture injection is a process by which solid particulate wastes may be combined with waste fluids into a suitable slurry mixture and injected at fracturing conditions into the deep subsurface for disposal (see Figure 1 below). The target injection formation is typically a high por Injection proceeds at a pressure sufficient to part the formation (fracturing pressure). When injection ceases, the parting zone closes and compresses under the natural in-situ stress conditions, the carrying fluid bleeds off rapidly into the surrounding formation, and the wastes solids are permanently held in place by the earth stresses.
Ongoing exploration and production activity, combined with increased regulatory requirements, are increasing the volume and costs associated with disposal of oil field wastes, including produced oily sands and tank bottoms, drilling mud and cuttings, crude contaminated surface soils, and naturally occurring radioactive materials (NORM). A cost-effective and environmentally sound disposal option is to re-inject waste material into the subsurface into non-productive and/or depleted zones under controlled fracture conditions. On-site deep well injection of exploration and production wastes provides significant environmental and cost advantages over traditional surface impoundment and landfill disposal. These include: 1. Improved protection for surface and groundwater; 2 3. Reduced transportation and disposal costs; 4. Reduced long-term liability risk to waste
Slurry fracture injection may also be applied to effectively manage municipal sanitation sludges in both dilute form direct from digesters, or in de-watered form (biosolids). Improved environmental management of biosolids (treated sewage residuals) is critical to sustainable urban development throughout the world. Most biosolids in the US are currently managed by application to farmland, lagoons, or landfills. As the ratio of farmland to urban areas decreases, this practice becomes increasingly difficult and restricted. For organic wastes, deep injection provides significant environmental advantages over land application due to the high temperature and pressure conditions. In the subsurface high temperature environment the biosolids will undergo a natural process of anaerobic biodegradation. This will fully treat (sterilize) the material within a period of days and within a period of months convert the organic mass to methane and carbon dioxide.enerator.strong
Reviewing the Definition of Rock Mechanics.
