Graphene aerogels have been a promising electrode material for high-power supercapacitors due to their three-dimensional porous structure and good conductivity. However, enhancing their electrochemical kinetics in a more realistic device setting is still a major challenge. In this work, the effects of nitrogen incorporation on the electrochemical performance of graphene aerogels were systematically examined by direct comparison of the electrochemical performance of pristine graphene aerogel (GA) and nitrogen-doped graphene aerogel (NGA). The materials were synthesized by hydrothermal reduction of graphene oxide and freeze-drying, and the nitrogen doping was made by a post-treatment modification step. Electrochemical characterization was carried out in the form of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) with a symmetric two-electrode setup and 6M KOH electrolyte. Both the electrodes showed quasi-rectangular CV profiles as well as symmetrical triangular GCD curves, thus representing a predominantly electric double-layer capacitance behavior. The specific capacitance was found to moderately increase from 174.18 F/g for GA to 187.54 F/g for NGA at 5 mA. More importantly, N modification significantly decreased the charge transfer resistance from 9.55 to 2.37 \(\:{\Omega\:}\) and the electrochemical relaxation time constant, leading to improved rate capability. These results show that the nitrogen incorporation mainly leads to an improvement in interfacial charge transfer kinetics and does not result in significant pseudocapacitive contributions to the supercapacitor kinetics, which is a useful insight for the design of high-rate graphene-based supercapacitor electrodes.
This study aims to mitigate the impact of electromagnetic interference on the performance of electronic systems in Unmanned Aerial Vehicles (UAVs) by employing various shielding materials. The materials tested include carbon fiber, E-glass, E-glass with an aluminium foil, and E-glass with a copper foil. A Vector Network Analyzer (VNA) and scattering parameter (S-Parameter) analysis, including reflection, absorption, and multiple reflection, were used to evaluate the shielding effectiveness of these materials within the frequency range of 4 - 5 GHz. The results showed that E-glass coated with copper had good overall shielding performance for SER, SEA, and SET values. This material reached a SET value of 96 dB at a frequency of 4.6 GHz, followed by E-glass coated with aluminium. In addition, adding carbon layers increased the shielding effectiveness, while E-glass without coating had the lowest shielding performance compared to the other materials. These findings indicate that E-glass coated with metal provides superior shielding effectiveness compared to carbon fiber, even when used in greater thickness.
A plug and abandonment (P&A) method using a support tool for cementing is presented. The production tubing is cut at a desired location, and the tubing is lifted some 20-30 meters, to later be left in hole. This 20–30-meter section is selected where the cement plug for the abandonment operation shall function as a barrier. Thereafter, cement slurry is placed at this location. In front of the cement slurry a cement support tool is pumped. This tool is designed to deploy in the well, covering the whole cross section area after deployment. This support tool hinders heavy cement slurries to migrate further down in the well. The presented results and observations are based on previous operations in Sabah water, where the cement support tool was used in a large number of plug cementing operations. The following timing and modus operandi are based on previous Hydraulic Workover Unit operations, with average handling speed for the tubing of 15 joints per hour, and 18 joints per hour for the 3-1/2″ drill pipe. The old and traditional method would require 4.9 days for the entire bottom plug operation. By use of the cement support tool, the time of this operation was reduced to 1.4 days. The result is a reduction equal to 3.5 rig days per bottom hole plug placement. In the paper this reduction in rig time is presented in detail
In October 2023, a proof of concept ("POC") to repurpose oil and gas industry end-of-life materials into artificial reef was undertaken in Malaysia as a collaboration between Sumitomo Corporation, Petroliam Nasional Berhad ("PETRONAS") and the Department of Fisheries, Malaysia ("DOFM"). For the aforementioned POC, surplus Oil Country Tubular Goods ("OCTG") casing pipes were used in the fabrication of purposefully designed artificial reef structures for the enhancement of biodiversity and commercial fisheries. This paper will share a brief overview of this initiative, the monitoring results and the replication of this concept in a subsequent project. This novel concept enables circular economy by repurposing end-of-life material into bespoke artificial reefs to target specific species or objectives. This greatly differs from traditional in-situ or ex-situ Rigs-to-Reefs ("RTR") initiative where the decommissioned offshore structures are deployed as artificial reef structures based on as-is condition, without any modifications. The X-to-Reef ("XTR") initiative serves to utilize decommissioned materials as building blocks and to provide scientific insights into design modifications of existing materials, enabling the end-of-life materials to be reefed with a purpose. In X-to-Reef, the ‘X’ represents any object or material—not limited to decommissioned offshore structures—that can be intentionally repurposed or redesigned into artificial reef structures, fostering a circular economy within the oil and gas ecosystem. For the POC in 2023, ten structures were fabricated from unused surplus OCTG casings, with bespoke designs targeting growth of commercial fisheries as well as seagrass. The flexibility and quick turnaround of this concept also enabled replication on another RTR project (Project 1) in 2024. From the initiation of discussion, the decommissioned caisson and boat landing structures from a twenty-year-old platform were transformed into five different artificial reef structures which were installed in Malaysian waters within four months from initiation of discussion. Physical monitoring surveys were conducted on the installed XTR structures on periodic basis to determine post-monsoon structural integrity, water quality as well as quantifying marine biodiversity and fish biomass. Results have shown that the installed artificial reef structures were structurally sound, without any detrimental effect on water quality based on physicochemical parameters. As of May 2025, 64 unique fish species were identified across the 10 POC artificial reef structures. While in terms of fish biomass, an improvement exceeding 1625% were observed at some structures. While RTR is an accepted industry practice, it often faces criticism due to the perception of cost-cutting during decommissioning and opportunistic dumping at sea. However, the XTR concept aims to repurpose end-of-life materials to create marine havens by transforming decommissioned materials into thriving ecosystems to mitigate climate change, support biodiversity, and enhance the resilience of marine environments. Additionally, it promotes local community's socio-economy and fosters a holistic approach to Sustainable Development Goals, in particular SDG1: No Poverty, SDG14: Life Below Water and SDG17: Partnerships For The Goals.
