25 September 2020
WiO asks: Which research areas continue to be interesting and necessary?
Water in Oil spoke to several produced water experts to understand which areas are likely to continue receiving attention despite the oil price downturn.
In response to market volatility caused by oil price crashes during the first half of 2020, operators across the globe have shelved upstream projects of all kinds. No R&D sector has escaped unscathed, but there are still bright spots out there. WiO reached out to researchers working in the academic and corporate communities for their perspectives on where produced water (PW) research remains necessary and which topics will continue to attract interest. Here are their insights:
Ngai Yin Yip, Columbia University (New York City, New York, USA)
“PW is highly diverse in its chemistry, and applications for reuse are also wide-ranging. Therefore, the starting feed and end product will be unique for each site, and a one-size-fits-all approach is unlikely to work. Instead, R&D for PW treatment should also pursue different approaches, but consistently focus on improving energy efficiency, ease of operation and, ultimately, cost effectiveness.
The prevailing distillation-based methods of desalination need to overcome the large enthalpy of water vaporization and are, hence, intrinsically energy-intensive. A better way to desalinate would be one that avoids the evaporative phase change of water. As such, osmotic membrane-based techniques (high-pressure reverse osmosis, osmotically-mediated reverse osmosis [RO] and forward osmosis) can be promising alternatives for the desalination of PW. Likewise, solvent extraction desalination also sidesteps the enthalpic penalty of vaporizing water and, thus, can be a step-change innovation.”
Prakhar Prakash, Chevron (Bakersfield, California, USA)
“Despite the downturn, we need to continue to improve our processes and efficiencies across operations. In our PW world, we should continue to look at improved de-oiling, particularly in established fields where there may not be an appetite to look for new technologies (say, ultrafiltration). Here, the preference is to improve de-oiling media performance.
Water softening for steamfloods is another area where improvement in regeneration efficiencies will save a lot of salts. This includes improved ion-exchange kinetics, low-fouling resin media and ways to reuse spent brine.
In addition, we need to look at new technologies for desalination, particularly for mid-range salinities (5,000-10,000 ppm of total dissolved solids [TDS]) where less pretreatment than RO is required.
Improvement in RO membranes which can withstand high temperatures is another opportunity for heavy oil and oil sands assets. Improved efficiency in gained output ratio with new thermal desalination technologies such as advanced multiple-effect distillation, mechanical vapor compression and membrane distillation are also worth exploring.
There is also a lot of interest in electrochemical processes for driving desired separation using electric charge.
Greater reliability in online measurement of oil and grease is another avenue which needs to be tested in field conditions.”
Laura Ferrando-Climent, Institute for Energy Technology (Kjeller, Norway)
“Most of the physicochemical technologies employed for PW treatment (membrane filtration, adsorption, precipitation and/or oxidation) have so far unveiled disadvantages, mainly due to their large acquisition and exploitation costs, as well as their inefficiency in the removal of special hazardous pollutants such as scale and corrosion inhibitors. Freshwater is scarce and costly in many arid regions, and it may be economically viable to reuse PW for both agricultural and domestic purposes.
There’s large potential in microalgae-based technology, for which deployment should be feasible in regions such as oilfields in Texas or the Middle East, where land is available adjacent to oilfields and there’s sufficient radiation to ensure microalgae blooming. Using natural sunlight as a radiation source, the technology would become almost passive. Energy consumption for such a treatment scheme would be very low compared to others such as membranes and would not require adding other chemicals to the water such as the powerful oxidants employed in advanced oxidation processes.
This microalgae-based approach would provide an economically viable method to reuse PW, e.g. for industrial reuse or agriculture. Moreover, the biomass slurry harvested from bioreactors might be further valorized to obtain nutrients for further use as crop fertilizers. Eventually, the biomass purged from reactors could be delivered to incineration plants for further recovery of their energy content. Under this new paradigm which integrates circular and bioeconomy approaches, microalgae can be seen as a useful bioresource to help turn PW into a valuable resource.”
Karim Ghasemipanah, Research Institute of Petroleum Industry (Tehran, Iran)
“We are looking at reducing COD [chemical oxygen demand] to environmental standards for discharging to seawater without desalination, as well as desalination of PW without reducing COD.
At some of our sites, we only need to reduce oil and COD levels in PW to discharge to sea – for example, in coastal or offshore sites – and don't need to reduce PW TDS. At onshore sites where we do have to reduce TDS, conventional desalination technologies such as multiple-effect distillation and multi-stage flash distillation have limitations on inlet COD of PW, which causes some problems in operation and fouling of these evaporators.
In coastal or offshore sites, we cannot use microbial technologies such as activated sludge to reduce COD in high-TDS PW, which may cause discharges of polluted water with high COD to sea. Finding solutions for these two obstacles will help operators ensure safe and environmentally friendly operations.”
Oswaldo Perez, Weatherford (Houston, Texas, USA)
The classical water conformance technique has been the applied methodology and process at reservoirs and wellbores to reduce water production, increase the recovery factor, minimize environmental impact and reduce operational costs. However, the overall success rate of these treatments is still low (about 5%). One of the reasons relates to failure to identify the source of the water influx, followed by ineffective solutions and challenging scenario injection and placement into wellbores or deep reservoir zones. The main problem is how to integrate data from the reservoir, production, geology and well history. The common industry practice is to analyze each of these categories independently and provide an isolated analysis (scattered data). To address this shortcoming, data analytics must be incorporated into the process to integrate every module into a single workflow, as described in the below diagram.