Three dimensionless parameters influencing the optimal membrane orientation for forward osmosis

Effects of membrane orientation on fouling characteristics of forward osmosis membrane in concentration of microalgae culture

This work presents new solutions to modeling the production performance of hydraulically fractured wells in unconventional reservoirs, where intensive hydraulic fracturing creates a stimulated reservoir volume (SRV) with an induced permeability field within.We found previously that the permeability field induced in the SRV (single porosity) can be effectively represented by an exponential or linear dependence of permeability on the distance measured from the main hydraulic fracture plane. However, many researchers consider dual porosity as a necessary ingredient in modeling unconventional reservoirs.In this work, we extend the induced permeability field model to the dual porosity idealization, considering transient fluid transfer from matrix to natural fractures and distance-dependent properties of the medium of secondary porosity (affected by the intensive stimulation).We show that the combined effect of creating a main fracture and altering the properties of the medium of secondary porosity leads to a production behavior that can be characterized and understood provided that effects related to skin and varying flowing bottomhole pressure are correctly accounted for.In addition to the standard diagnostic tools for decline-curve or rate-transient analysis, we use the ratio between the production time and material balance time, a dimensionless group that enables identifying the characteristic signatures of flow regimes. We provide practical criteria to identify various scenarios affecting the data during the pre-linear and prebilinear flow regimes in the reservoir (short times). Then we show that transient, late transient and boundary dominated flow periods can also be diagnosed using the dimensionless group, providing a useful addition to existing procedures involving conventional plots.In connection to the new model, this work also discusses a novel approach to handle non-constant bottomhole pressure, the cause of significant distortion in production data at early times. In particular, we consider the effect of a bottomhole pressure exponentially approaching a stabilized value. We show that the deviation from the idealized constant bottomhole pressure case depends on the flow regime in the reservoir, fluid and reservoir properties, skin factor, and the mean lifetime (the time when 63% of the total change has happened) of the decaying part of the flowing pressure. The results reveal that half-, three-fourths-, and unit-slope straight lines (on log-log plot of production rate versus time) develop at short times during the increasing trend of production rate. These new flow regimes enable to gain useful information about the SRV from the early stage of the production history – if the quality of data allows such a detailed analysis.We present a field example involving multi-fractured horizontal wells producing from a shale-gas reservoir, to illustrate, in a practical manner, how to apply the new approach when interpreting production history of wells in unconventional reservoirs.

A series of carboxyethyl amine sodium salts (CASSs) with different carboxyl group numbers are synthesized as draw solutes for forward osmosis (FO) application. Their chemical structures are examined by 1HNMR and HRMS. FO performances are investigated and compared in terms of different physicochemical properties. The effects of the CASS concentration on the osmotic pressure and viscosity of the draw solutions, as well as the resulted FO performance are also systematically investigated. A high water flux of 23.07 LMH and an acceptable reverse salt flux of 0.75 gMH can be achieved with 0.5 g mL−1 triethylenetetramine hexapropionic acid sodium (TTHP‐Na) draw solution under PRO mode, which is superior to most other draw solutes reported in previous literatures. TTHP‐Na draw solution is further evaluated to recycle the Congo red solution via FO process to examine its applicability for waste water treatment. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1226–1235, 2016

The present work aimed to study the efficiency of thermal osmosis process for recovery of water from organic wastewater solution and study the factors affecting the performance of the osmosis cell. The driving force in the thermo osmosis cell is provided by a difference in temperature across the membrane sides between the draw and feed solution. In this research used a cellulose triacetate (CTA), as flat sheet membranes for treatment of organic wastewater under orientation membrane of active layer facing feed solution (FS) and draw solution (DS) is placed against the support layer. The organic materials were phenol, toluene, xylene and BTX (benzene, toluene, and xylene) used as feed solution. The osmotic agent in draw solution was sodium chloride salt. The membranes have high rejection percentage for NaCl and organic materials. In this research, the operating conditions that have been studied are: temperature of draw and feed solution (18 – 45 °C) and the operating time of process was (0 – 3) hours. It was found that water flux in thermal osmosis process increases with increasing temperature of draw and feed solution ( by average ratio 1:2), and decreases with increasing operating time.

Elucidating two-phase transport in a polymer electrolyte fuel cell, Part 1: Characterizing flow regimes with a dimensionless group

Sulfonated polysulfone supported high performance thin film composite membranes for forward osmosis

To advance commercial application of forward osmosis (FO), we investigated the effects of two additives on the performance of polysulfone (PSf) based FO membranes: one is poly(ethylene glycol) (PEG), and another is PSf grafted with PEG methyl ether methacrylate (PSf-g-PEGMA). PSf blended with PEG or PSf-g-PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaCl (1 mol∙L–1) and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSf with 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L∙m–2∙h–1 than the commercial HTI membranes (6–8 L∙m–2∙h–1) under the FO mode. Our study suggests that hydrophobic interface is very important for the formation of polyamide, and a small amount of PSfg-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization. Open image in new window

Exploring the use of cheap natural raw materials to reduce the internal concentration polarization in thin-film composite forward osmosis membranes

Anchoring polyamide active layer to improve the thermal stability of polyacrylonitrile composite forward osmosis membrane through interfacial enthalpic effect

Anti-fouling and high water permeable forward osmosis membrane fabricated via layer by layer assembly of chitosan/graphene oxide

The significance of convection, density driven flow, for placement of proppant during hydraulic fracturing has been discussed in the literature. In this study, small glass model was constructed to simulate a fracture. Newtonian and non-Newtonian fluids with controlled density differences were used and variables such as density difference, viscosity, fracture width, proppant concentration, and flow rate were considered. Proppant placement efficiency in the experiments was interpreted with two dimensionless groups. One group compares viscouse and gravity effects and the other compares convective and dispersive effect. The experiments showed that the pattern formed by the boundary between the displaced and the displacing fluids is very simmilar to that observed in much larger models. It has been noticed that convection is very significant even with very small density differences. As viscouse to gravity ratio increases by reducing gap width or increasing the displacing fluid viscosity, the effect of convection becomes less and proppant placement efficiency tends to increase resembling that of Craig et al.1 for gravity override in reservoirs. The effect of convective-dispersive group was found to be small compared to the viscouse to gravity group. The experiments conducted were simulated using an excutable code (GOHFER) and the results indicate that proppant slurry transport can be accurately modeled.

Chemical and bioassay assessment of waters related to hydraulic fracturing at a tight gas production site

Synthesis of novel thin film nanocomposite (TFN) forward osmosis membranes using functionalized multi-walled carbon nanotubes

Water is the most common and heavily used fluid in the petroleum industry. It is produced along with oil and gas from nearly every well. Fresh water is used as a base fluid in drilling, completion, and production operations. Produced water is handled in three primary ways: injected in salt water disposal wells, for pressure maintenance in secondary or tertiary recovery projects, or as a recycled base fluid in hydraulic fracturing. In unconventional oil and gas operations hydraulic fracturing is the biggest user of fresh water. The focus of this paper is the procurement, conditioning, transportation, storage, reuse and disposal of water for hydraulic fracturing in Newfield's MidContinent operations. Newfield's two primary fresh water sources are subsurface aquifers and surface water. The transportation of either fresh water or recycled (produced) water can be done by either pipeline or truck. Where possible it is preferable to transport the water through pipelines. For the transportation of smaller volumes of water 3" or 4" poly pipe is used or the water is trucked. Large volumes of fresh water are generally moved through 10" aluminum irrigation line, although polyvinyl chloride (PVC), lay flat hose, and high density polyethylene (HDPE) are also used. For the transportation of recycled or produced water HDPE has been the choice for most operators. Newfield's preference for storing fresh water is unlined ponds because they can then be used by a landowner for long term water supply on his or her property. Lined pits are used where the soil conditions will not prevent water from leaking out. Fresh water can also be stored in frac tanks (500 bbl), modular tanks (up to 60,000 bbl), or portadams (sized as required). Recycled or produced water is stored in permitted lined pits, frac tanks, modular tanks, or portadams. After fracturing a well, the produced water used can be recovered, stored, and reused. If the produced water cannot be reused it will be disposed via deep well injection (most common disposal method) or evaporation (limited use). The amount of produced water recovered after stimulation is dependent on the formation characteristics. Usually from 20 to 80% of the water used during the fracturing operation is recovered within the first 60 days of production and can be reused. Depending on the quality of the produced water recovered, it may require some type of treatment prior to reuse. Newfield began recycling water in its Wheeler County, Texas operations during 2005 because it made economic sense and the company is committed to responsible environmental stewardship.

Currently, Russia experienced a rapid growth in horizontal wells drilling. The most popular method of completion is hydraulic fracturing. About 99% of hydraulic fracturing fluids are prepared using water. This fact undoubtedly increases the importance of technology and practices of collecting and utilizing water from underground and surface sources. The current direction of development of multi-stage hydraulic fracturing is increasing the number of stages and the volume of the proppant. So the main task of fracturing companies in Russia is to optimize the process of collecting and preparing water without increasing the cost of hydraulic fracturing. The use of organometallic fluids fracturing is the most common solution for use of unconventional water sources. However, due to the high cost of organometallic liquids, borate fluids will be considered in this work. Existing quality control requirements applied to hydraulic fracturing fluids cannot be directly used to study the rheological properties of fluids based on alternative sources of water — produced water from artesian wells and low temperature water. In connection with the foregoing, in the framework of this work, a new approach to testing and quality control of hydraulic fracturing fluids is presented. In case of using water with low temperature (15 degC in summer, 25 degC in winter), it is crucial to maintain the required recovery rate of fluid viscosity after application of high shear rates when passing through perforations in the near wellbore zone. In the case of the use of artesian water, it will be crucial to maintain the necessary stability of the liquid in a highly mineralized medium. During the hydraulic fracturing campaign in 2017-2019, pilot works were carried out using low temperature water and water from artesian wells. Implementation of water with a lower temperature leads to a reduction in the time of preparation for hydraulic fracturing by 33-50% reduction in heating time for the fluid. As a result, this practice leads to an increase in the monthly amount of work and the production of hydraulic fracturing fleets. Extended laboratory studies revealed that, developed for low temperature conditions, the hydraulic fracturing fluid not only satisfies the parameters for transferring and holding the proppant in the NWB zone, but even surpasses the liquid prepared by the traditional method (25 degC in summer, 35 degC in winter). The main goal of optimization of hydraulic fracturing fluid prepared using artesian water was to reduce the negative impact of some ions, primarily iron ions and hydrocarbonate ions. The presence of these ions in the hydraulic fracturing fluid leads to deterioration of the thermal stability of the hydraulic fracturing fluid. However, following the recommendations developed for the preparation of a fracturing fluid based on artesian water, it is possible to significantly reduce the influence of both one and other ions. The use of artesian water in the area of pads located near artesian wells, has reduced the time of water transportation by 50%. Pilot treatments were successfully carried out, showing a satisfactory level of production after hydraulic fracturing, comparable to similar work using conventional surface water preparation techniques using the standard procedure. Reduction of preparation time, optimization of resources required for water treatment, and reduction of negative environmental impact confirm the significant economic benefits of the methodology described in this paper. This approach, using the environmentally safe "green" chemistry as part of a hydraulic fracturing fluid, allows operators to minimize the negative impact of production factors on the environment and confirm the effectiveness and environmental friendliness of hydraulic fracturing technology as a well workover.