Oil & Natural Gas Projects
Exploration and Production Technologies
|Swellable Organosilica Materials to Clean Produced Water
||Last Reviewed 6/24/2013
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.
Absorbent Materials Corporation (ABS Materials), Wooster, Ohio 44691-9359
The primary commercial and research focus of this project is the treatment of flowback 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 with the development of hydraulic fracturing technology 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 fracturing process, the well is depressurized and 10–40% of the water is recovered from the system. This flowback water generally contains high levels of dissolved solids, fracturing chemicals, and hydrocarbons extracted from the formation. The challenge industry faces is determining what to do with the flowback 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 flowback water are important for developing this substantial domestic energy source.
Flowback 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 address dissolved hydrocarbons, slicking agents, and polymers, which can prevent flowback water from being recycled or discharged.
This project examines a novel and innovative solution to treat flowback 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 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 flowback fluid clean-up costs, effectively clean flowback 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.
Accomplishments (most recent listed last)
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.) flowback 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 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 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 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 flowback water used for the evaluations.
A pilot unit (VOC Capture Unit) was designed and built based on a replaceable cartridge design and capable of a 1 bbl./min flow rate. The VOC Capture 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 improve both the pilot unit design and provide a means to evaluate Osorb® regeneration concepts. Industrial wastewater 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 that had waste water too contaminated to be treated at a POWT facility. The industrial wastewater was similar to produced water in that regard. The trials successfully demonstrated that the waters could be cleaned to suitable discharge limits, but the cost to treat per barrel was too high. 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. (DOE indicated that this goal was not of high priority and can be considered completed.)
Lessons learned during field trials with the 1.5 bbl./min pilot unit indicate that a significant cost to 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 that constitute Osorb® is important. Even a < 1% loss of Osorb® during operations and recovery operations adds significant cost to processing a bbl of water. Researchers are reducing the finished goods cost of Osorb® using several approaches. The first is to replace a portion of the expensive silane monomer with less expensive silane monomers. Secondly, improvements to 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. A combination of these approaches can lead to a reduction in the finished goods cost of Osorb®.
The other major cost driver is regenerating the Osorb® for re-use. Handling loose Osorb® causes some loss of material by accidental spillage. The current regeneration process requires the transfer of loose Osorb® from the capture and collection processes to the current thermal regeneration by a rotary dryer process. The Osorb® is handled once again when transferred from the regeneration dryer to the feed hoppers. Design improvements to utilize sealed canisters to contain the Osorb® can significantly reduce accidental spillage; however, this proposed solution presents its own challenges for regeneration. These efforts focus 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® and that a flow-through system is 8–10 times more effective than a batch system of solvent cocktail rinsing. Challenges still exist and include determining how to effectively remove the rinsing solvent cocktail from the canister and design and regeneration of the Osorb-filled canister for re-use. Additionally, alternative rinsing solvents (e.g., supercritical carbon dioxide and low pressure steam) are being investigated.
Current Status (June 2013)
Reducing the finished goods cost of Osorb continued to be a major effort this past reporting period.
- A 50 percent reduction in the amount of Osorb particles—generated during particle reduction operations—that were too small was accomplished by changing the grinding equipment. The amount of unsuitable Osorb® particles was reduced from 30 to 15 percent, which translates to an 18 percent reduction in the cost of finished goods Osorb®.
- First-time product quality was improved through the design and construction of a custom solvent rinsing system for Osorb, improved sieve operation techniques, gradation measurements, and VOC capture effectiveness tests.
Regeneration of Osorb® for continued re-use was another major development effort this reporting period.
- A laboratory-sized, novel solvent extraction instrument was rented. A series of evaluations demonstrated that typical BTEX compounds are readily removed via the novel solvent extraction instrument. Researchers are currently evaluating how to remove the more difficult-to-remove heavy dispersed oils typical of flowback and produced water. The target oil is walnut oil because there is readily available information from the food industry using the novel solvent extraction instrument and walnut oil. Subsequent experiments will center on Osorb® saturated with Ohio crude oil. Next steps are to design and build a larger-scale system from readily available components. The learning goals are to determine design feasibility and cost-effectiveness in the use and integration of the novel solvent extraction regeneration system as a component of the cartridge-based excursion unit/ VOC Capture systems.
- Osorb regeneration using low-pressure steam in the seal canister developed for the “excursion unit” continued to demonstrate positive results. A 15 minute exposure of synthetic crude oil-saturated Osorb® to low-pressure steam removed 55–60 percent of the compounds. Compounds as heavy as pentadecane (C15 hydrocarbons) were removed. The process is currently being evaluated using Ohio crude oil as a replacement for the synthetic crude oil mixture.
- A rinsing system was designed and built that includes a larger canister with a 22 liter capacity and utilizes the solvent cocktail. This rinsing system has two purposes: (1) to conduct solvent regeneration studies and (2) to use the Osorb manufacturing /finishing process to remove undesirable chemicals. The rinsing system is very effective for these two tasks.
There were very limited opportunities during the past six months for field testing the PWU 1.5 at an active drilling pad/fracturing site. Several small-scale (275 gal /1000 liters) paid pilots for the canister-based VOC Capture system of oil, hydrocarbons, chlorinated solvent, and/or aromatic chemical contaminated industrial waters were conducted. These industrial waters were used as a source of chemically tainted water and presented learning opportunities for deploying the VOC Capture system and determining effectiveness of the smaller, yet comparable, VOC Capture system. Two of the three pilots behaved as expected while the third did not, the difference being that an oil-water emulsion in the contaminated industrial water formed that required a much longer contact time with the Osorb to break-down and effectively capture oil. Knowledge gained from treating these contaminated industrial water can be applied to many of the types of waters expected to be encountered in the flowback and produced water segments.
Project Start: June 19, 2010
Project End: August 14, 2013
DOE Contribution: $1,082,434
Performer Contribution: $175,000
NETL – John Terneus (email@example.com or 304-285-4254)
Absorbent Materials Corporation (ABS Materials) – Stephen Jolly (firstname.lastname@example.org) or 330-234-7999)
If you are unable to reach the above personnel, please contact the content manager.