Produced-water treatment: Application and research of combined fiber coalescence technique in offshore oilfield

When the process of extraction of oil from an offshore oilfield enters the advanced stages,the water content in the extracted fluid can be above 90%.The water quality is complex with many types of pollutants and highly emulsified water.Therefore,a key consideration in the production process of offshore oilfields is the efficient and economical treatment of the oil-containing produced water to make it suitable for discharge and recover oil pollutants.In this study,we developed a hydrophilic and hydrophobic combined fiber coalescence separator with composite fiber shapes using fiber induction and X/Uweaving.The separator is designed based on experimental observations of the mechanism of structure coalescence in the physical oil removal method.A pilot test was performed on an oil exploration platform in the Bohai Sea.At the designed flow rate,the separator reduced the total concentration of petroleum in the produced water from 2000 to 3000 mg/L to below 60 mg/L,with an average oil removal efficiency of 98.24%.Furthermore,it effectively reduced the number of organic compounds present in the water from 120 to 17 and removed 70% of the SS.The test results show that the proposed device can be used fr produced-water treatment on offshore platforms.

Compressive fatigue behavior and failure evolution of additive fiber-reinforced cemented tailings composites

The ordinary cemented tailings backfill(CTB)is a cement-based composite prepared from tailings,cementitious materials,and water.In this study,a series of laboratory tests,including uniaxial compression,digital image correlation measurement,and scanning electron microscope characteristics of fiber-reinforced CTB(FRCTB),was conducted to obtain the uniaxial compressive strength(UCS),failure evolution,and microstructural characteristics of FRCTB specimens.The results show that adding fibers could increase the UCS values of the CTB by 6.90%to 32.76%.The UCS value of the FRCTB increased with the increase in the polypropylene(PP)fiber content.Moreover,the reinforcement effect of PP fiber on the CTB was better than that of glass fiber.The addition of fiber could increase the peak strain of the FRCTB by0.39%to 1.45%.The peak strain of the FRCTB increased with the increase in glass fiber content.The failure pattern of the FRCTB was coupled with tensile and shear failure.The addition of fiber effectively inhibited the propagation of cracks,and the bridging effect of cracks by the fiber effectively improved the mechanical properties of the FRCTB.The findings in this study can provide a basis for the backfilling design and optimization of mine backfilling methods.

Spectral Beam Combining of Fiber Lasers by Using Reflecting Volume Bragg Gratings

By employing three reflecting volume Bragg gratings, a near-infrared 4-channel spectral-beam-combining system is demonstrated to present 720 W combined power with a combining efficiency of 94.7%. The combined laser beam is near-diffraction-limited with a beam factor M^2-1.54. During this 4-channel beam-combining process, no special active cooling measures are used to evaluate the volume Bragg gratings as combining elements are under the higher power laser operation. Thermal expansion and period distortion are verified in a 2 k W 2-channel beam-combining process, and the heat issue in the transmission case is found to be more remarkable than that in the diffraction e-se. Transmitted and diffracted beams experience wave-front aberrations with different degrees, thus leading to distinct beam deterioration.

Fabrication of side pump combiners when pumping with a laser diode and a fiber laser

Side pumping combiners are widely used in fiber laser schemes for their high coupling efficiency, low insertion loss, and multi-point pumping capability. However, side pumping combiners perform differently in coupling efficiency when pumping with a laser diode(LD) and a high-brightness 1018 nm Yb-doped fiber laser(YDFL). In this paper, for the first time, to the best of our knowledge, we investigated the different parameters to fabricate the(2 + 1) × 1 combiner with high coupling efficiency when pumping with an LD and a YDFL, respectively. After optimization, the maximum coupled pump power from one single-pump port of the combiner was 1200 W and 2730 W when pumping with a LD and a YDFL, respectively.

Supercontinuum generation with 15-fs pump pulses in microstructured fiber with combination core and random cladding

We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.

Coherent beam combination of two fiber amplifiers with multi-dithering technique

Coherent beam combination of two W-level fiber amplifiers with multi-dithering technique is demonstrated.In the experiment,the master laser is split into two channels.Multi-dithering technique is used for phase control.One channel is modulated with a 100 kHz sine wave produced by signal generator,and DSP lock-in amplifier is used for electric signal processing in the feedback loop.When the phase control loop is off,the far field interference pattern is blurred and dynamic with 20% fringe contrast.When the feedback loop is closed,the far field interference pattern is clear and stable with 72% fringe contrast,and 75% coherent combination efficiency is achieved.

Improved all-optical OR logic gate based on combined Brillouin gain and loss in an optical fiber

Improved all-optical OR gates are proposed, using a novel fiber nonlinearity-based technique, based on the principles of combined Brillouin gain and loss in a polarization-maintaining fiber （PMF）. Switching contrasts are simulated to be between 82.4%-83.6%, for two respective configurations, and switching time is comparable to the phonon relaxation time in stimulated Brillouin scattering （SBS）.

Humidity and temperature sensor based on GOQDs-PVA coated tapered no-core fiber combined with FBG

A simple structure optical fiber sensor for relative humidity(RH) and temperature measurement is proposed and verified in this paper, which is based on graphene oxide quantum dots and polyvinyl alcohol(GOQDs-PVA) composite coated tapered no-core fiber(NCF) combined with a fiber Bragg grating(FBG). FBG is insensitive to humidity and sensitive to temperature, which is used to compensate temperature of the sensor. Experimental results show this sensor has humidity sensitivity of 143.27 pm/%RH ranging from 30%RH to 80%RH and the temperature sensitivity of 9.21 pm/℃. The proposed sensor has advantages of simple structure, good repeatability, and good stability, which is expected to be used in both RH and temperature measurement in biological and chemical fields.

152 W high-power blue diode laser operated at 447 nm

We demonstrate a high-power blue diode laser operated at 447 nm combining laser diodes using an optical fiber bundle. As many as 127 diode lasers at 447 nm were coupled into 400 μm/0.22 NA fibers using an aspherical lens group with different focus lengths. The bare fibers were mechanically bundled through high temperature ultraviolet adhesive after the coatings of the 127 fibers were stripped. The diameter of the fiber bundle was 6 mm. The total output power of such a bundle was 152 W with electro-optical conversion efficiency of 27.56%and the RMS power instability was less than ±1% within 3 h.