For shale exploration and development, the current portfolio of water treatment tool allows a new field application tool, which concerns mainly the use of vibrating membrane filtration technology for wastewater recycling.

It is estimated that for each barrel of unconventional oil and gas production, it takes up to 20 barrels of water, multi-well shale resources need a lot of water; onshore shale mining operations is currently facing one of the most challenging problems. Therefore, continuously monitored by authorities and the public, pushed by limited treatment options and increasing costs, the application of water treatment technologies highlighted its varied degrees of success, such as in-situ electro-coagulation method (EC) and ultraviolet (UV) disinfection methods, which are very favorable for operators to reduce device power consumption and production cost.

Recently, a unique design, ultra mobile membrane separation technique has been emerged as a cost-effective method option, mainly for water, gas, or shale oil shale development, it reaches up to 80% performance output for treatment or recovery,. Double towers AQUA-VES mobile water treatment system uses a cross-flow vibration isolation, it can process and recycle back fracturing drainage, waste oil and gas, mining and waste water from drilling and completion well, up to 2,500 barrels .

Different from regular systems, to remove some but not all wastewater contaminants, the new trailer-mounted water treatment technology applications in the field proved that it can put out all the impurities, including total suspended solids (TSS) bacteria, oxidized metals, fat, oil, other total petroleum hydrocarbons (TPH), entrained in the slurry within a certain percentage of total dissolved solids (TDS).

The on-site treatment system, using vibrating membrane filtration technology, has been applied successfully in the Permian Basin, Marcellus Shale, Eagle Gefu Te (Eagle Ford) and other shales. Based on a complete life cycle of the water treatment service, the system is able to use only one kind of microfiltration / ultrafiltration or nanofiltration, to remove the very small 0.0005 microns (μ) of the material. This tiny solids removal can pave the way for sustained recycle; otherwise it brings out waste water and subsequently turn out extra costs up to $ 18 / barrel of transportation and handling in some shale mining.

The new research direction of the film separation

Over the years, membrane filtration as a method of purifying water, mainly due to its selection by the aperture and the separation of its superior ability to control the separation. The traditional water treatment systems of film separation applied for shale exploration and production, mostly adopt cross-flow filtration, requiring high flow rates to keep the filter clean. This method not only requires more energy to operate, but also filter a relatively small proportion of the total flow.

In the conventional cross-flow filtration, the majority of the shear turbulence generated away from the boundary layer, thus effectively removing retained particles. Therefore, the film is easy to plug, and the flow rate decrease. On the other hand, cross-flow induce vibration, concentrate on the membrane surface shear waves, exclude within other boundary pollutants and solid particles. This method allows a higher concentration, while maintaining long-term continuous use rate which is higher than the standard filtration system, up to 10 times.

This vibration isolation method is designed as the latest generation of water treatment technology. The new system uses a membrane coated with Teflon of 0.05μ thickness, to keep the vibration, which means that fluid velocity is controlled by the vibration rather than the flow. Therefore, the diffusion from the membrane surface shear waves, so keep suspended particles remain on the surface, allowing more liquid through the membrane transport. Therefore, the film remains clean than conventional filtering techniques by up to 15 times; the new system allows unrestricted flow filtration over a relatively large proportion of the substance. Due to the high-throughput, without even any dirt on membrane, the system is extremely energy-efficient, per one thousand gallons of filtrated liquid it needs only 0.27 kwh.

In addition, the vibration membrane system adopts surface filtration instead of deep filtration. When the membrane cleaning is necessary, it can be done on the surface, not requiring disassembly nor non-productive time as requested by cleaning deep filtration device. Because durable Teflon membrane coatings can tolerate almost all cleaning compounds, include strong acids and solvents, plus the regular contaminations in the past.

How to operate

The system is running at 16 m (53 ft) trailer position, which can accommodate skid mounted pump units and two film towers. Each module contained in a very small 1.3m ×1.3m (4 feet ×4 feet) pads are stainless steel trays, which can accommodate about 400 continuous vibration micro / ultrafiltration membrane, allowing transfer of 112 square meters (1,200 square feet) of the cross-flow. Before the beginning of the processing operation, site specific wastewater samples were analyzed to determine the number of stages required for filtration and processing. According to the operating environment, this system is able to adapt to a variety of membrane pore size, from microfiltration to reverse osmosis.

In the operation, the mud come in from the top of the vibration units, alternating downward flow blockage forced sewage into the cross-flow. Since the slurry going through the diaphragm and the units can flow continuously, thereby generating a vibration of the centrifugal force, which makes heavier material into the open groove, extending along the film to the top plate unit? Separated material fall down to the bottom of the groove. Meanwhile, the filtrated clean solution is forced to go up, which is pumped into the fracture and complete recovery tank.

Because only substances less than 0.05μ can flow through membrane plate, vibrating membrane separation system effectively extract all of the metal oxide, bacteria, suspended solids, some of the TDS, and all hydrocarbons.

Site application performance comparison

Compared with other process on-site, this technology combines EC, UV and evaporation, proved that it has a unique advantage, the quantity of contaminants removed by vibrating membrane separation system is large with big diversity of types, and it can be consistently delivered of cleaning material, and therefore, 80% of the entire slurry can be re-processed freshly and return to active flow, for further use by subsequent drilling operation.

In addition, compared to water treatment systems, this new technology is that the system is the only one adapted to remove all types of pollutants. For example, some processes can only remove suspended substances, while some others are adapted to extract only the biological contaminants and TDS. Moreover, the vibration membrane technology can remove TSS, bacteria, TPH, oxidized metal and some TDS, based on the amount of processing its costs could reach as low as $ 1.50 / barrel.

For more information, please visit Zoranoc's official website: www.zoranoc.com