BACKGROUND
The production of conventional and unconventional oil and gas resources is accompanied by the production of large volumes of produced water (PW). PW contains high concentrations of total dissolved solids (TDS) and oil. TDS of PW includes high concentrations of toxic metals (e.g., Ba, Sr, Cd, Cr, and As). Oil includes dissolved and emulsified oil mostly composed of n-alkanes. Concentrations of n-alkanes and toxic metals in PW is orders magnitude higher than in conventional wastewater. A combination of high concentrations of n-alkanes and toxic metals does not only pose a risk to human health, but it also hinders the reutilization of PW 1as a drilling or hydraulic fracturing fluids, the integration of PW into industrial and agricultural uses, and/or the safe disposal of PW.
SUMMARY OF TECHNOLOGY
Researchers at OSU have developed a method to remove dissolved and emulsified oil (mostly n-alkanes) and heavy metals from petroleum produced water (PW) which consists of a two-stage treatment process. The first stage is to remove dissolved and emulsified oil from PW through a known microbiological stimulation of indigenous oil degrading methanogenic microbial communities that are adapted to high salinity conditions. The second stage is novel and removes heavy metals using filters made of compressed powdered dolomite of uniform grain size. Here, increased levels of heavy metals removal are achieved by filtrating PW previously treated for oil. To further increase the removal efficiency of the dolomite filter, calcium and magnesium is removed from PW by the addition of lime and soda ash in a sedimentation tank, and guar gum is supplied to PW to enable the trapping of heavy metals by guar gum in small pore throats of the dolomite filter.
POTENTIAL AREAS OF APPLICATION
- Industrial or Agricultural use
- Oil & Gas Exploration
MAIN ADVANTAGES
- Allows reuse as a drilling or hydraulic fracturing fluid, industrial or agricultural use
- Safe disposal in surface or subsurface.
- Inexpensive and simple to implement treatment of large volumes of PW
STAGE OF DEVELOPMENT
This technology is currently available as a proof of concept.