|Swellable Organosilica Materials to Clean Produced Water
||Last Reviewed 12/12/2013
The goals of this project are to (1) develop and improve several water treatment technologies to remove dispersed and dissolved organic species from produced water with a focus on flow back water treatment and (2) develop a production process to make these technologies commercially viable.
ABS Materials Inc., Wooster, Ohio 44691-9359
The primary commercial and research focus of this project is the treatment of flow back water resulting from gas field hydraulic fracture stimulations. Unconventional natural gas is an important growing domestic energy supply typically found in shale plays. The challenge industry faces is determining what to do with the flow back water. The Energy Information Agency (EIA) projects shale gas natural gas production will continue to grow, reaching 45 percent of the total volume of produced U.S. natural gas by 2035.Thus, advanced methods to treat flow back water are important for developing this substantial domestic energy source.
Flow back water is an amalgamation of dispersed oil, dissolved volatile and semi-volatile organics, organic acids, metal ions, radionuclides, oilfield treatment chemicals, salt, polymers, insoluble material (rock dust, organic species), or any combination of these. However, very little effective technology exists to address dissolved hydrocarbons, slicking agents, and polymers, which can prevent flow back water from being recycled or discharged.
This project examines a novel and innovative solution to treat flow back water dissolved organics by using swelling glass - Osorb®, which is an engineered organosilica material with high porosity. Osorb® functions as nanomechanical sponge since the porous matrix rapidly swells up to eight times its dried volume upon exposure to non-polar liquids. Osorb® does not swell in water, but is highly effective at removing a wide range of free or dissolved organics from water, including polar species (such as alcohols and carboxylic acids) and non-polar species (such as toluene, benzene, naphthalene, nonane, octane, and 90 percent of naturally occurring organic acids). The goal is to engineer Osorb-based materials into systems that will reduce flow back fluid clean-up costs, effectively clean flow back water streams, and create purified water that can be safely discharged to the environment. Recovered hydrocarbon products can be sold or used as fuel to power the purification system.
Successful development of the Osorb-based materials to remove hydrocarbons and organic process chemicals would benefit the treatment of flow back water and produced water in the following ways:
- Significantly reduce water storage and disposal costs.
- The portable treatment unit would reduce off-site water hauling and associated costs.
- Water can be recycled for fracturing operations or returned as agricultural water in arid regions
- Modification of the base Osorb® formulation may allow for selective removal of metal and/or radionuclide contaminants from Marcellus Shale flow back and produced waters.
The project has completed all Phase I objectives. ABS Materials, in conjunction with three global oil service companies, designed and built a trailer-mounted, 3600 gallon per hour (gal/hr) flow back water purification system for field use. One major oil services company, with scientific leadership present, was contracted to conduct a full pilot test in the field using produced water from the Clinton formation (Ohio) in July 2010 and March 2011. Total petroleum hydrocarbon (TPH) levels were reduced from 227 mg/L to 0.1 mg/L during testing. TPH is a more stringent measurement than oil and grease, indicating the treated water was well below the discharge threshold of 29 mg/L. This test successfully demonstrated the effectiveness of Osorb® in a large system.
ABS Materials has finished the build of PWU 1.5, a 65 gal/min fully automated treatment system mounted upon a 53 ft drop deck trailer. Successful wet testing was conducted in June 2012 with fresh water only. Successful wet testing with the addition of Osorb® and the recovery of Osorb® from the fresh water was completed in August 2012. The system is available for customer use and field trials. A pilot unit was designed and built based upon a replaceable cartridge design and capable of a 1 bbl/min flow rate, VOCCapture Unit. The VOCCapture unit is being used on contaminated industrial waste and the lessons learned can be utilized to improve both the pilot unit design and provide a means to evaluate Osorb® regeneration concepts. Industrial waste water is a substitute for produced water in these field trials. The system is modular in design allowing for easy scale up to higher bbl/min flow rates. This system was trialed at three industrial companies that had waste water too contaminated to be treated at a POWT facility. The industrial waste water was similar to produced water in that regard. Lessons learned are being incorporated into current research efforts to reduce the costs to process waters.
Osorb® modified with organic groups that bind metals ions were developed and were able to selectively bind certain cations. ABS Materials completed bench-scale testing of forms of Osorb® that co-extract radionuclides (ex. 235U, 212Pb, 228Ac). In addition, ABS Materials has begun looking at formulations that can be used to harvest rare earth cations from produced water.
Current Status (December 2013)
Lessons learned during field trials with the 1.5 bbl/min pilot unit indicateed that a significant cost of processing produced water using Osorb® technology rests in two main areas. The first is the finished goods cost of Osorb® and the second is costs associated with regenerating Osorb® for re-use.
Reducing the cost of the raw materials comprising Osorb® is important. Even a < 1% loss of Osorb® during operations and recovery operations significantly increases the cost of processing a bbl of water. The cost of Osorb® is being reduced via several approaches. The first is to replace a portion of the expensive silane monomer with less expensive silane monomers. Secondly, improving the manufacturing methods to reduce Osorb® production time requirements from the current 1.5 weeks; learning to manufacture the reduced cost, mixed-silane Osorb® formula; and improving first time quality are being investigated. Project personnel have improved the final yield of suitably sized, graded Osorb® by15 wt% by changing the grinding machine from a disc grinder to another mode. A sealed canister system utilizing a solvent cocktail was built to remove excess production chemicals to <300ppm, giving a clean product with minimal leaching characteristics. The combination of these approaches is reducing the finished goods cost of Osorb®.
The other major cost driver is regenerating the Osorb® for re-use. The design improvements to utilize sealed canisters to contain the Osorb® are significantly reducing the costs associated with accidental spillage. However, canisters of Osorb®es to thermal energy, novel system processes, and pilot system designs to regenerate the Osorb® within the canisters.
ABS Materials has a combined solvent wash plus low-pressure steam follow-on treatment in one system that is proving to be very effective. A combined ( solvent plus steam) regeneration of an Osorb® ( 5.0 kg) that captured mixed-phenols and BETX from a Gulf of Mexico off-shore platform reduced contamination levels from 12,000 ppm to <200ppm in 50 minutes.
A second approach to the regeneration challenge is utilizing super-critical CO2 (SC-CO2) technology. ABS Materials’ technical team selected leading SC-CO2 system designer, Thar, to partner with. Initial testing demonstrated that 5.0 kg of Osorb® containing 20 percent corn oil in a wet state was regenerated, removing > 85 percent of corn oil. Corn oil was selected because it presents a “worst case” and is non-toxic. The latest efforts are focusing on determining the lowest pressure possible to effectively remove corn oil like molecules from Osorb® with SC-CO2. The project team has completed the first 2 of 7 steps to get to the point where a suitable system can be designed, built, and tested using the sealed Osorb® canisters.
Project Start: June 19, 2010
Project End: August 14, 2014
DOE Contribution: $1,082,434
Performer Contribution: $175,000
NETL – John Terneus (firstname.lastname@example.org or 304-285-4254)
Absorbent Materials Corporation (ABS Materials) – Stephen Jolly (email@example.com) or 330-234-7999)
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