Oil & Natural Gas Projects
Exploration and Production Technologies
|Swellable Organosilica Materials to Clean Produced Water
||Last Reviewed 12/15/2012
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.
Absorbent Materials Corporation (ABS Materials), 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 and growing domestic energy supply typically found in shale plays. Access to shale gas has been made possible by the development of hydraulic fracturing technology (frac) where water, proppant (graded sand), and a mix of chemical additives are injected under high pressure to induce fractures in shale formations for gas extraction. At the conclusion of the frac process, the well is depressurized and 10–40% of the water is recovered from the system. This flow back water generally contains high levels of dissolved solids, fracing chemicals, and hydrocarbons extracted from the formation. 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% 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. Several treatment techniques separate dispersed oils from water. These methods take advantage of the density difference between oil and water, thus functionally removing solids or dispersed oils from the water. However, very little effective technology exists to remove 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 a swelling glass, Osorb®, which is an engineered organosilica material with high porosity. Osorb functions as a 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% of naturally occurring organic acids). The swelling process is completely reversible—with no loss in swelling behavior even after repeated use (at least 100 times)—when absorbed species are evaporated by heating the material. 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 fracking 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.
All Phase I project objectives have been completed. 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. The trailer mounted system was demonstrated to several global oil company representatives at ABS’s Ohio headquarters. One major oil services company, with their scientific leadership present, 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 completed the construction of PWU 1.5, a 65 gal/min fully automated treatment system mounted on a 53 ft. drop deck trailer. Wet testing with fresh water only was successfully conducted in June 2012. Wet testing with the addition of Osorb® to and recovery of Osorb® from the fresh water was successfully completed in August 2012. The system is available for customer use and field trials.
A smaller footprint, mini-skid, two-cartridge system containing 1.3 kg of Osorb® was developed to replace the larger footprint skid unit for use by GPRI-Texas A&M on their mobile showcase trailer. The mini-skid two-cartridge system was demonstrated by GPRI at two sites in Pennsylvania during the summer of 2012. The results were inconclusive and were believed to be due to the low level of dissolved hydrocarbons present in the flow back water used for the evaluations. Analyses of the results are still in progress.
A pilot VOCCapture unit capable of a 1 bbl/min flow rate was designed and built based upon a replaceable cartridge design. The VOCCapture unit is being used on contaminated industrial waste process water because clients are willing to pay for the field testing and lessons learned can be utilized to both improve 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 tested by three industrial companies whose waste water was too contaminated to be treated at a (Publically Owned Wastewater Treatment) POWT facility. The industrial waste water was similar to produced water in that regard. The trials successfully demonstrated that the water could be cleaned to suitable discharge limits, but the cost per barrel to treat it was too high. Lessons learned are being incorporated into current research efforts to reduce processing costs.
Osorb® (modified with organic groups that bind metal ions) was developed and found to selectively bind certain cations. ABS Materials completed bench-scale testing of forms of Osorb® that co-extract radionuclides (ex. 235U, 212Pb, 228Ac). ABS Materials also has begun looking at formulations that can be used to harvest rare earth cations from produced water.
Current Status (December 2012)
The project team is searching for a field test site to test the ability of the PWA 1.5 Capture Trailer System to remove BTEX (benzene, toluene, ethyl-benzene and xylene), grease and oils and, potentially, polymeric surfactants. The goal is to reduce the total contaminates concentration from 100 to 200 ppm to 10 ppm or to meet other customer defined requirements. The project team is searching for a site that has either (1) late stage flowback frac water in tanks, (2) a frac water containment pond, and/or (3) an Injection well.
Lessons learned during field trials with the 1.5 bbl/min pilot unit indicate that the significant cost to process produced water using Osorb technology is due to two factors: the finished goods cost of Osorb® and the 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 adds significantly to the cost of processing a bbl of water. The cost of Osorb is being reduced by replacing a portion of the expensive silane monomer with less expensive silane monomers, and by investigating methods to manufacture a reduced cost, mixed silane, Osorb formula; reduce Osorb production time requirements by 1.5 weeks; and improve initial quality. The other major cost driver is regenerating the Osorb for re-use. The current process involves physically transferring loose Osorb from the capture and collection process area to a rotary dryer for thermal regeneration. The Osorb is then transferred from the regeneration dryer to the feed hoppers. Design improvements that utilize sealed canisters to contain the Osorb significantly reduce the chance of accidental spillage. However, having a canister of Osorb material presents its own challenges for regeneration. Current efforts are focused on alternatives to thermal energy, novel system processes, and pilot system designs to regenerate the Osorb within the canisters. It was found that a solvent “cocktail” is more effective than solvent alone in rinsing the collected hydrocarbons from Osorb. It was further established that a flow-through system is 8–10 times more effective than a batch system for solvent cocktail rinsing. Challenges still exist and include determining how to effectively remove the rinsing solvent cocktail from the canister and regenerate the Osorb-filled canister for re-use. Additionally, alternative rinsing solvents (e.g., supercritical carbon dioxide and low pressure steam) are being investigated.
Project Start: June 19, 2010
Project End: August 14, 2013
DOE Contribution: $599,663
Performer Contribution: $75,000
Loan/Donated Materials: $100,000
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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