Evaluation of anionic and non-ionic surfactant performance for Montney shale gas hydraulic fracturing fluids

Hydraulic fracturing is often used in unconventional shale reservoirs, and 50%–95% of the injected hydraulic fracturing fluid remains in the formation due to the capillary effect. This phenomenon has been observed in the Montney shale formation, Canada, where the flowback water recovery is generally less than 25%. Surfactant is one of the hydraulic fracturing fluid additives for reducing surface tension and capillary forces to facilitate water flowback recovery. Surfactant loss due to adsorption by the reservoir rocks reduces the chemical’s efficiency, and this causes water retention in the formation and reduces water flowback recovery. The compatibility of surfactant with reservoir rock is critical to minimize surfactant adsorption on the rock surface because this diminishes the primary function of the surfactant hydraulic fracturing fluid additive and to ensure cost-effectiveness. This study evaluates surfactant efficiency to improve flowback recovery for the Montney shale formation based on IFT, surface tension, and adsorption. This study evaluates surfactant performance and performs a fluid–fluid interaction experiment and fluid-rock compatibility investigation. Several commercial surfactants are screened for low interfacial tension and surface tension. Further analysis is carried out by evaluating the fluid-rock compatibility using the static soaking test at reservoir pressure and temperature. The pre-soaking and post-soaking test fluids were analyzed for water composition, liquid–liquid interfacial tension, surface tension, and pH. Results showed that the selected surfactant is a critical determiner of the hydraulic fracturing fluid performance. SOLOTERRA 938 is an anionic surfactant that has good compatibility with Montney shale formation. Unlike other non-ionic surfactants, SOLOTERRA 938 retains the interfacial tension and surface tension after seven days of interaction with reservoir rock. The interfacial tension remained unchanged at 0.1 mN/m. The surface tension decreased from 28.4 to 27.5 mN/m with air and from 21.7 to 20.8 mN/m with hydrocarbon because surfactant behavior changes with pH change. The surfactant concentration was measured using high-pressure liquid chromatography, and the loss was 12% after seven days of interaction with the reservoir rock (from 0.1 to 0.088wt%). The adsorption calculated based on the concentration volume showed a low value of between 0.43 and 0.97 mg/g rock.

Fluorescence and biological stabilization of phosphorous-functionalized mesoporous silica nanospheres modified with a bis(8-hydroxyquinoline) Zn complex

Greenish-emitting phosphorous-functionalized mesoporous silica (PMPS) nanospheres were fabricated by modifying their surfaces with (8-hydroxyquinoline) zinc (Znq2). Simulated body fluid soaking test and subsequent gas-adsorption measurement revealed that Znq2-modification could dramatically...

Improving the Photostability of Small-Molecule-Based Organic Photovoltaics by Providing a Charge Percolation Pathway of Crystalline Conjugated Polymer

Photostability of small-molecule (SM)-based organic photovoltaics (SM-OPVs) is greatly improved by utilizing a ternary photo-active layer incorporating a small amount of a conjugated polymer (CP). Semi-crystalline poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) and amorphous poly[(2,5-bis(2-decyltetradecyloxy)phenylene)-alt-(5,6-dicyano-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2CNBT) with similar chemical structures were used for preparing SM:fullerene:CP ternary photo-active layers. The power conversion efficiency (PCE) of the ternary device with PPDT2FBT (Ternary-F) was higher than those of the ternary device with PPDT2CNBT (Ternary-CN) and a binary SM-OPV device (Binary) by 15% and 17%, respectively. The photostability of the SM-OPV was considerably improved by the addition of the crystalline CP, PPDT2FBT. Ternary-F retained 76% of its initial PCE after 1500 h of light soaking, whereas Ternary-CN and Binary retained only 38% and 17% of their initial PCEs, respectively. The electrical and morphological analyses of the SM-OPV devices revealed that the addition of the semi-crystalline CP led to the formation of percolation pathways for charge transport without disturbing the optimized bulk heterojunction morphology. The CP also suppressed trap-assisted recombination and enhanced the hole mobility in Ternary-F. The percolation pathways enabled the hole mobility of Ternary-F to remain constant during the light-soaking test. The photostability of Ternary-CN did not improve because the addition of the amorphous CP inhibited the formation of ordered SM domains.

Kinetics of Quality Changes in Soaking Water during the Retting Process of Pepper Berries (Piper nigrum L.)

There are organic matters and bioactive compounds naturally present in pepper that may have leached out into the soaking water due to a prolonged retting process that caused changes in water quality. This study was carried out to determine the influences of different quantities of mature pepper berries and soaking time on the quality of soaking water during the retting process. The soaking test was conducted by having three tanks with different quantities of pepper berries soaked in the 18 L of water. The results show that the tank with the highest quantities of pepper berries has the highest increment of turbidity from 21.80 ± 1.90 NTU to 1103.30 ± 23.10 NTU (98%), the highest reduction in pH from 6.99 ± 0.02 to 3.67 ± 0.02 (47.50%), the highest reduction in dissolved oxygen from 5.19 ± 0.17 mg/L to 1.05 ± 0.02 mg/L (79.77%) and the highest increment of chemical oxygen demand from 21.67 ± 1.15 mg/L to 3243.33 ± 5.77 mg/L (99.33%) compared to other tanks. Furthermore, the zero, first and second-order kinetic models fitted well with the experimental data of the quality of soaking water for three conditions using the Arrhenius law approach. Thus, these findings are useful for estimating water quality during the retting process.

Influence of Multi-Phase Carboxylate Salt on Mortar Properties under Sulfate Environment

A novel multi-phase carboxylate (MPC) salt was prepared by free radical polymerization. Influence of MPC salt on properties of mortar under sulfate environment was investigated. The results from static solution soaking and wet-dry cycling tests indicated that MPC would not bring negative effects on strength and shrinkage of mortar. In particular, MPC was able to reduce the strength loss as a result of inhibiting the generation and growth of ettringite in static solution soaking test. The crystal expansion of AFt was reduced since the Ca2+ dissolution and SO42- ingress were less. Meanwhile, the strength loss of mortar under sulfate wet-dry cycling could be reduced as well by MPC. MPC inhibited the growth of CaSO4·2H2O crystals by replacing the functional groups. The growth of micro-cracks in cement paste was inhibted and the the risk of crystal expansion and destruction of mortar was reduced. It was believed that MPC exhibited an excellent sulfate attack resistance for mortar.

COMPARATIVE STUDY OF CORROSION BEHAVIOR FOR PLASMA NITRIDED 1045 CARBON STEEL WITH AND WITHOUT PRETREATMENT OF SAND BLASTING

A pretreatment of sand blasting with the duration of 15[Formula: see text]min was carried out prior to plasma nitriding for 1045 carbon steel in this study. The corrosion behavior was evaluated by means of electrochemical polarization, electrochemical impedance spectroscopy (EIS) and soaking test, and compared with that without pretreatment of sand blasting. The results show that the pretreatment of sand blasting can significantly enhance the corrosion resistance, the corrosion potential shift to the noble direction, with higher corrosion potential of [Formula: see text][Formula: see text]mV and lower corrosion current of 0.0853[Formula: see text][Formula: see text]A/cm2, and exhibit larger diameter, higher phase angle and wider frequency region, there exists no corrosion pit after soaking test, and the corrosion rate is decreased from 0.0387[Formula: see text]g/mm2 to 0.01341[Formula: see text]g/mm2, only 1/3 comparing with that of sample without pretreatment of sand blasting. The enhancement mechanism of corrosion behavior is mainly ascribed to the excellent protection from the thicker and denser compound layer with higher amount of [Formula: see text]-Fe[Formula: see text]N.

Bioactive and Antibacterial Ag-AgCl-TiO2 Coating on Titanium Implants

In this work, Ag-AgCl-TiO2 coating was fabricated on titanium substrates to obtain an implant material having excellent antibacterial property and bioactivity. The coating was investigated by scanning electron microscopy and X-ray diffraction. The bioactivity of coatings was examined by simulated body fluid soaking test. To verify the susceptibility of implant material surface to bacterial adhesion, S. aureus (Sau), E. coli (Eco), K. pneumoniae (Kpn), P. Aeruginosa (Pae), four types of major pathogen were chosen for in vitro antibacterial analyses. The results showed that Ag-AgCl-TiO2 coating had excellent antibacterial property and bioactivity.