Numerical approach on production optimization of high water-cut well via advanced completion management using flow control valves

Abstract With the development of smart downhole control devices, such as the electric flow control valve (FCV), research on completion optimization using FCV control is gaining traction for successful field production management. Applying and verifying its applicability to actual assets with uncertain production issues occur are important. This study focuses on managing downhole devices to optimize fluid production in an actual onshore oil field in Alberta, Canada. The target field has been in production operation for over 20 years, and water flooding was used in the early stages of production to maintain reservoir pressure. However, according to the flow characteristics of the field, water injection caused a high water-cut issue due to water channeling. To mitigate the problem, proactive and reactive strategies were investigated to optimize FCV control. Additionally, the effect of completion optimization was estimated considering both the field-level economic value and the fluid production behavior at the device level. In most optimization cases, the cumulative water production could be reduced compared with the base case without valve control. Notably, the flow-balancing strategy increased the revenue of the target field by approximately 23 MM$ by maximizing oil production and suppressing water production. However, reactive and streamline-balancing strategies, which directly control and delay water production, undermined the economic value due to the decrease in oil production. The findings imply that FCV control strategy of suppressing only water production for the field with high water-cut could not be the optimal solution considering the reduction in oil production and the field’s revenue. The results of this study could be used as a reference to optimize downhole devices when applying water flooding in fields where high water-cut is expected

Synergistic effect of Pt-loaded Co–N–C electrocatalysts for hydrogen evolution reaction in alkaline conditions

© 2022 Elsevier B.V.Designing efficient electrocatalysts for the hydrogen evolution reaction (HER) is important for a renewable and sustainable hydrogen economy. Alkaline HER remains particularly challenging because it involves water dissociation in addition to hydrogen recombination. Herein, we developed a simple precursor solution-based electrocatalyst in which Pt nanoparticles (NPs) are positioned independently of the Co-dispersed nitrogen-doped carbon (Co-N-C). The Pt/Co-N-C catalyst exhibited enhanced HER activity in an alkaline electrolyte compared to Pt/C and Co-N-C, achieving a decreased overpotential (33 mV at 10 mA cm−2) and lower Tafel slope (36.8 mV dec−1). Comparison of HER activities under acidic and alkaline electrolyte conditions revealed that the synergistic enhancement of Pt/Co-N-C was only obtained under the alkaline condition. Evaluation of the adsorption/desorption of H or OH through cyclic voltammetry analysis suggested that Co-N-C support can play a role to facilitate water-dissociation under alkaline conditions and leads to a larger charge ratio of Hupd/OHad on Pt, thus improving the HER activity at the Pt NP active sites.11Nscopu

Highly Sensitive Ultraviolet Photodetector Based on an AlGaN/GaN HEMT with Graphene‐On‐p‐GaN Mesa Structure

Abstract The advantageous role of 2D electron gas presence at the AlGaN/GaN interface attracts huge interest in the field of GaN‐based ultraviolet photodetector technology. However, the presence of high dark current deteriorates the photodetector performance by diminishing several figures of merit. In this work, enhanced figures of merit are demonstrated by employing interdigitated p‐GaN finger structure on the top of the AlGaN/GaN heterostructure. The commonly present high dark current in p‐GaN/AlGaN/GaN planar photodetector is largely reduced (from ≈µA to few pA) by etching the p‐GaN, excluding the electrode region. Furthermore, by using a graphene transparent electrode along with the p‐GaN interdigitated fingers on AlGaN/GaN heterostructure, ultraviolet photodetectors with superior sensitivity (3.55 × 106) and ultrahigh detectivity (1.91 × 1014 cm Hz1/2 W−1) are realized at 360 nm. A comparison of graphene/p‐GaN and Ni/Au/p‐GaN interdigitated fingers and planar p‐GaN (with interdigitated graphene contacts) all on AlGaN/GaN heterostructure allows to understand the dominant roles of electrode transparency and the heterojunction structure. The simple and high electron mobility transistor‐compatible fabrication process of UV detectors provides a unique application in the field of UV sensing technology

Space Radiation Effect on Si Solar Cells

High energy charged particles are trapped by geomagnetic field in the region named Van Allen Belt. These particles can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-1) was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-1 orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-1 solar cell degradation was caused by energetic protons which energy is about 700 keV to 1.5 MeV. Our result can be applied to estimate solar cell conditions of other satellites