Theia was contacted by a customer who provides treatment systems for water coming from fracking and other drilling operations. In this case, they were looking at treating sour produced water at a site in Texas. The challenge was to treat and remove the Hydrogen Sulfide (H2S) in the produced water so that it could be re-used for hydraulic fracturing fluid for the end user. This customer offers an array of solutions which include chemicals as well as high tech solutions such as ozone injection. They wanted to show the end user that they could affordably reduce the H2S while still meeting the stringent criteria set forth. Naturally, considering the typical expense of treating sulfides, the end user was a more than a little skeptical
Theia shipped the customer one of our test nozzles, an OX550H (the Oxygenator), which uses ambient oxygen to directly oxidize H2S and other compounds (i.e. iron and manganese), while also dissolving oxygen into the water to prevent reformation of H2S.
Testing:
We worked with the customer to set up testing conditions as close to optimum as was feasible, then ran a number of tests. Inlet H2S levels in the produced water fluctuated from 165 to 150 mg/l. the flow of water was 550 g/m.
Unlike submerged aerators or oxygen injection, the reaction is immediate. The customer utilizes sampling locations in the pipe before and after the Oxygenator nozzle itself. Most technologies require reaction chambers and long contact times to achieve the same results, which often means large tanks for the process.
The Oxygenator is a very simple device; the entire system encompasses a pump, an Oxygenator nozzle and some piping. There is nothing to maintain, nothing to clog, and all equipment remains external to the process and easily accessible. The system requires no chemical handling or storage, increasing safety and mitigating environmental risks. Additionally, all equipment is external to any tanks or lagoons, meaning access is available without anyone having to go into the water.
Results:
The Oxygenator was able to reduce the H2S levels from an inlet level of 150-165 mg/l to 50 mg/l simply by passing the water through the nozzle twice. As the sulfide level dropped, the pH of the produced water went up. While this development is typically a positive one, the change in pH from 6.2 to 7.8 converted most of the remaining H2S to HS-.
HS- can be oxidized using the Oxygenator. However, the reaction time and oxygen required for the conversion goes up significantly. Because the system design was based on the immediate conversion, the customer tried other methods to oxidize the remaining sulfides. Ozone worked but the amount of ozone required was impractical. Hydrogen peroxide was able to reduce the sulfides further but requires a 4:1 dosage ratio to do so.
Another option would be to simply reduce the pH back down which would have allowed the Oxygenator to finish the job.
Summary:
The pilot test proved out the technology and allowed our customer to provide a solution to the customer at a fraction of the cost of anything else in the industry. The simplicity and low capital costs (as well as operating costs) can often dissuade skeptics from even trying the process. We all learn at a young age that sometimes when things seem too good to be true, they must be. As our customer learned, this is not one of those cases!
