Three-dimensional convective dissolution of carbon dioxide into brine

The sequestration of carbon dioxide (CO2) through storage into deep saline aquifers represents an indispensable support technology to achieve the zero-carbon target necessary to mitigate the impact of CO2 on climate change. The effectiveness of the sequestration process, partly driven by the convective dissolution of CO2 in brine, is nowadays well characterized for two-dimensional geometries, low permeabilities, and small pressures of injection of CO2. However, reliable predictions of process-efficiency are missing because of the lack of full understanding of the three-dimensional (3D) spatio-temporal behaviour of CO2-rich convective fingers in brine over a large range of injection pressures. Here, we show that the convective dissolution is determined by the instability of the boundary layer formed at the interface between the two phases and is totally independent of the overall vertical size. Experiments were conducted over a broad range of injection pressures, close to process-relevant conditions. The results show the formation of complex 3D structures, including interconnecting stream tubes at the CO2-liquid interface, which could not be detected in previous 2D Hele-Shaw studies, and fingerings. A scale-free theoretical modelling of the convective process allows us to remap our laboratory results to length-scales of relevance for geological reservoirs. The experiments and the model show that the times needed for the onset of convection and the convective flux are independent of the system size.

EXPERIMENTAL STUDY ON THE INJECTION CHARACTERISTICS OF HYDROTREATED VEGETABLE OIL IN A DIESEL ENGINE COMMON RAIL SYSTEM

The diesel combustion is primarily controlled by the fuel injection process. The start of injection therefore has a significant effect in the engine, which relates large amount of injected fuel at the beginning of injection to produces a strong burst of combustion with a high local temperature and high NOx formation. This paper investigated the impact of Hydrotreated Vegetable Oil (HVO) and blends of 10%, 20%, 30%, 50%, 80% by mass of HVO with commercial diesel fuel (mixed 7% FAME-B7) to injection process under the Zeuch’s method and compared to that of B7. The focus was on the injection flow rate in the variation of injection pressures, back pressures, and energizing times. The experimental results indicated that injection delay was inversely correlated to HVO fraction in the blend as well as injection pressure. At different injection pressures, HVO revealed a slightly lower injection rate than diesel that resulted in smaller injection quantity. Discharge coefficient was recognized larger with HVO and its blends. At 0.5ms of energizing time, injection rate profile displayed the incompletely opening of needle. Insignificant difference in injection rate was observed as increasing of back pressure.

Using the BBraun BSmartTM Pressure Manometer to Prevent Unsafe Injection Pressures During Simulated Peripheral Nerve Blockade: A Pilot Study

Background: Peripheral nerve injury during regional anaesthesia may result from accidental intraneural placement of the needle, or forceful needle nerve contact. Intraneural injections are associated with increased resistance to injection, typically >15 psi. The BBraun BSmart™ is an inline mechanical manometer, offering a visual display of injection pressures. Objective: The primary objective of this study was to determine if using the BBraun BSmartTM manometer successfully prevents 90% of anaesthetists and anaesthetic assistants from injecting at pressures > 15 psi during simulated nerve block. Methods: This was a prospective observational study involving anaesthetists and anaesthetic assistants. Two 20 ml injections were performed by each participant, once when the BBraun BSmartTM manometer was obscured from view, and once with the manometer visible. A PendoTech PressureMATTMS recorded injection pressures. Results: 39 participants completed the study, with a total of 78 injections recorded. During the study, 32 peak pressures during the 78 procedures were recorded above the recommended upper limit of 15 psi, 41% of the total injections. The peak pressure rose above 15 psi in 24/39 (62%) injections when the BBraun Bsmart™ manometer was obscured, but only in 8/39 (21%) injections when the manometer was visible. Conclusion: The BBraun Bsmart™ manometer did not successfully prevent 90% of anaesthetists or anaesthetic assistants from injecting at unsafe pressures. However, using the BBraun BSmart™ did reduce the number of unsafe injection pressures generated by participants. When utilised in conjunction with PNS and ultrasound guidance, this may offer additional safety during peripheral nerve blockade.

The experimental investigation of diesel fuel-biofuel blends at different injection pressures in a DI diesel engine

In this study, it was aimed to investigate the effects of a diesel-biodiesel blend (B20) and a diesel-biodiesel-bioethanol blend (BE5) on combustion parameters in addition to engine performance and exhaust emissions compared with diesel fuel. Parameters included in the evaluation was brake specific fuel consumption, brake thermal efficiency, CO, CO2, HC, NOx, smoke opacity emissions and finally cylinder pressure, heat release rate, ignition delay, some key points of the combustion phases such as start of ignition, start of combustion, CA50 and CA90 and combustion duration. Engine tests were conducted at different injection pressures of 170 bar, 190 bar, which is the original injection pressure, and 220 bar by the engine being loaded by 25, 50, 75 and 100% for the assessment of engine performance and exhaust emissions. For combustion evaluation, the data obtained at 1400 rpm, maximum torque-speed, and 2800 rpm, maximum power-speed were used, while the injection pressures were set to 170, 190 and 220 bar under full load condition. According to test results, the better performance characteristics, exhaust emissions and combustion behaviour of engine were obtained with the use of BE5 at high injection pressure. So, BE5 fuel improved brake specific fuel consumption by about 7% and brake thermal efficiency by about 6% compared to B20. In addition, while the emission values of BE5 gave better results than diesel fuel, it reduced the NOx and smoke emissions of B20 by approximately 1.4% and 6.4% respectively. Moreover, it has achieved a reduction in smoke emission of up to 45% compared to diesel fuel.

Evaluation of Injection Strategies in Supersonic Nozzle Flow

The ability to manipulate shock patterns in a supersonic nozzle flow with fluidic injection is investigated numerically using Large Eddy Simulations. Various injector configurations in the proximity of the nozzle throat are screened for numerous injection pressures. We demonstrate that fluidic injection can split the original, single shock pattern into two weaker shock patterns. For intermediate injection pressures, a permanent shock structure in the exhaust can be avoided. The nozzle flow can be manipulated beneficially to increase thrust or match the static pressure at the discharge. The shock pattern evolution of injected stream is described over various pressure ratios. We find that the penetration depth into the supersonic crossflow is deeper with subsonic injection. The tight arrangement of the injectors can provoke additional counter-rotating vortex pairs in between the injection.

Numerical study for the spray characteristics of diesel engine powered by biodiesel fuels under different injection pressures

Great attention is directed towards the study of the spray phenomena theoretically and experimentally due to its dramatic effect on the combustion process that occurred in an internal combustion engine, in particular, the diesel engine. The spray macroscopic characteristic of diesel engines fueled with two different biodiesel fuels in addition to nominal diesel under various injection pressures has been investigated numerically in this work. The selected biofuels are Rapeseed methyl ester (RME), Waste cooking oil methyl ester (WCOME). The Russian simulation software Diesel-RK is used in this work. Four different injection pressures are used which are 200, 500, 800 and 1000 bar respectively. It is found that RME has higher spray penetration with a narrow spray angle due to high viscosity and large momentum compared to diesel fuel. The results reported that biodiesels have greater Sauter mean diameter (SMD) compared to pure diesel because of their higher viscosity and surface tension. Promising reduction in SMD comes with WCOME as the injection pressure increases. Cylinder pressure along with heat release is reduced in the case of biodiesel due to the reduction in heating values. The lowest ability to produce smoke is recorded for WCOME where 93% reduction is achieved followed by a 57% reduction for RME as compared to diesel. The obtained results are compared with the results of other researcher and the convergence between them is observed.

Offshore CRI Well Performance Diagnostics and Fractured Domain Mapping Using Injection Data Analytics and Hydraulic Fracturing Simulation, Verified Through 4D Seismic and Wireline Logging

The cuttings re-injection (CRI) well in the Astokh area of Piltun-Astokhskoye field offshore Sakhalin Russia is one of the longest operating drilling waste disposal wells in the oil and gas industry worldwide. The Astokh area has been developed as a waterflood and is operated by Sakhalin Energy, a joint venture between Gazprom, Shell, Mitsui, and Mitsubishi. The Astokh CRI well has been utilized for waste injection for over 16 years. About 300,000 m3 of waste has been disposed into the main injection zone of the CRI well. Monitoring and modelling the CRI process to understand the evolution of the disposal domain is paramount for safeguarding further disposal operations. The disposal domain can be described as a complex system of multiple hydraulic and natural fractures due to injection under fracturing conditions. CRI domain evaluation includes analysis of historical injection pressures to identify the reasons of continuous injection pressure increase with increasing cumulative waste volumes disposed, to confirm domain containment, and to predict remaining domain capacity. Transient pressure analysis has revealed that the fracture closure pressure, driven by pore pressure increase and the accumulation of injected solid-phase waste, is the key parameter affecting injection pressures. Injection intensity, periods of shut-in, large overflushes, and solids-free liquids injections with corresponding solids and stresses redistribution are the other factors that affecting the pressure trends. CRI domain mapping was carried out with history-matched time-lapse 3D hydraulic fracture models. Injection pressure history matching results reveal the fracture geometry evolution during well life. The distribution of the injected liquid phase in the sand layers was modeled with a 3D dynamic reservoir sector model, matched with injection pressures and with formation pressure data in two offset wells, located at a distance of 1 and 2 kilometers, respectively. A matched model was then used to assure fracture containment for future waste disposal and to estimate remaining domain capacity. High-precision temperature and spectral noise logs were acquired in seawater injection and shut-in modes. The log-derived fracture height confirmed the domain size predicted by the matched model. 4D seismic data processing revealed that dimensions of Geomechanically Altered Rock Volume (GARV) were also in the same range as predicted by the model p. The integration of CRI domain evaluation with matched 3D hydraulic fracture models, well logs and 4D seismic demonstrated that injection pressure data collected during every injection cycle may be sufficient to characterize disposal domain evolution and to estimate domain capacity.

Laboratory-Scale Investigation of the Utilisation of Multiple Flat-Fan Nozzles in Descaling Petroleum Production Tubing

Despite the recent wide embrace of mechanical descaling approaches for cleaning scales in petroleum production tubings and similar conduits with the use of high-pressure (HP) water jets, the process is still associated with downhole backpressure and well integrity challenges. While the introduction of sterling beads to replace sand particles in the water recorded high successes in maintaining well completion integrity after scale removal in some recent applications of this technique, it is, unfortunately, still not without questions of environmental degradation. Furthermore, the single nozzle, solids-free, aerated jetting descaling technique – recently published widely – is categorized with low scale surface area of contact, low descaling efficiency and subsequent high descaling rig time. The modifications to mechanical descaling techniques proposed in this work involve the use of three high-pressure flat fan nozzles of varying nozzles arrangements, standoff distances and injection pressures to remove soft scale deposits in oil and gas production tubings and similar circular conduits. This experiment provides further insights into the removal of paraffin scales of various shapes at different descaling conditions of injection pressures, stand-off distances and nozzle arrangements with the use of freshwater. The results obtained from this study also show consistency with findings from earlier works on the same subject.