Investigations on the effect of silver nanoparticles on performance of coconut oil based cutting fluid in minimal fluid application

In this work, an innovative nanocutting fluid, based on coconut oil was developed by dispersing silver nanoparticles (AgNPs) of size less than 50 nm. The tribological and physical properties of the prepared nanocutting fluid with different volumes of silver nanoparticles were studied. It was found that the addition of 4% by volume of nanoparticles enhanced the properties of the nanocutting fluid compared to the other concentrations studied, thus demonstrating its excellent tribological performance. The effect of the newly developed nanocutting fluid with 4% of silver nanoparticles on cutting performance was also investigated while machining AISI4340 steel with minimal fluid application. Results revealed that the cutting force, cutting temperature, and tool wear are reduced on an average by 22.6%, 12.6%, and 5.3% respectively. It was evident that efficient cooling and lubrication of nanocutting fluid dispersed with silver nanoparticles improved the cutting performance. The outcomes of this work can be considered as a development toward eco-friendly and sustainable machining.

Analysis of Riser Gas Pressure from Full-Scale Gas-in-Riser Experiments with Instrumentation

As the use of adaptive drilling process like Managed Pressure Drilling (MPD) facilitates drilling of otherwise non-drillable wells with faster corrective action, the drilling industry should review some of the misconceptions to produce more efficient well control methods. This paper discusses results from full-scale experiments recently conducted in an extensively instrumented test well at Louisiana State University (LSU) and demonstrate that common expectations regarding the potential for high/damaging internal riser pressures resulting from upward transport or aggregation of riser gas are unfounded, particularly when compressibility of riser and its contents are considered. This research also demonstrates the minimal fluid bleed volumes required to reduce pressure build-up consequences of free gas migration in a fully closed riser.

Use of Micronized Weighting Agents for High Density Completion Fluids: A Case Study

A unique invert emulsion fluid (IEF) weighted up with treated micronized weighting agent (MWA) slurries has been developed and successfully implemented in the field as a completion and testing fluid. The utilization of this unique IEF by design allowed the fluid properties to be lower on viscosity and superior suspension characteristics, which allowed for thermally stable fluid and provided excellent downhole hydraulics performance. Much of the earlier development and deployment of this type of IEF was focused on drilling for sections in narrow mud weight and fracture gradient windows, coiled tubing operations, managed pressure drilling, and extended reach wells. Many of these drilling challenges are also encountered in high pressure and high temperature (HTHP) and ultra-deepwater field developments and mature, depleted fields. Early fluid developments focused on designing the fluids chemistry and physics interactions and the optimization of mineralogy of the weighing agent used. There was also some concern on variability of the results seen on the return permeability as well as standard fluid loss experiments. The paper describes the laboratory and field and rigsite data generated while using the MWA in IEFs during completion operations with a client in India. The paper will briefly describe the laboratory work before the application and the associated results observed on the rig site. It will also outline all the challenges which were faced during the execution and mixing of the MWA IEFs. Each separate operation required a high-density reservoir fluid solution above 15.5 ppg [1.85 sg]. Because corrosion, sag potential, and scale were the operator's main concerns, a solids-free brine or other type of weighting agent (for e.g. Calcium Carbonate and/or Tri-Manganese Tetra Oxide) solution was not favored. A high-density IEF designed with MWA allowed us to provide a solution that mitigated against the risks identified in each operation. The thin viscosity profile enabled completion activities to proceed with minimal fluid consumption at surface, reducing the overall environmental impact. The high-density (15.6 ppg [1.86 SG] and 16.2 ppg [1.94 SG]) invert emulsion fluid was designed to minimize sag potential with minimal reservoir damage potential. With a thinner viscosity profile compared to conventional IEFs at equivalent densities, the fluid enabled completion activities with minimal fluid volumes lost over shakers and reduced the environmental impact. The MWA that was used to build the IEF used for drilling and completion fluid enabled maintenance of extremely low-shear rate viscosities when compared to conventional barite-laden fluids. This fluid was used for suspending and abandoning the well in Case Study A, where the reentry and intervention of the well was planned to be after 2 years. After exposure of the fluid in Case Study A, the fluid showed minimum sag after re-entry of the well and the intervention activities were done without any problems. Case Study B showed that the fluid was mixed to the density of 16.2 ppg and was used to perforate and test two different zones. The bottom hole static temperature (BHST) reported were 356 degF (180 degC) for Case Study A and 376 degF (191 degC) for Case Study B respectively. The paper attempts to show the effects of using this alternative weighing agent as a completion fluid instead of a high-density solids-free brine or other solids-laden high-density brines and the associated success, which could be managed if the fluid design is carefully planned.

Minimal and Locally Edge Minimal Fluid Models for Resource-Sharing Networks

We investigate minimal and locally edge minimal fluid models for real-time resource-sharing networks, which are natural counterparts of pathwise minimal and locally edge minimal performance processes for the corresponding real-time stochastic systems. The models under study arise as optimizers of appropriate idleness-based criteria within a suitable family of fluid models for a given resource-sharing network. The class of minimal fluid models is fairly general, corresponding to efficient service protocols in which transmission on each route takes place in the earliest deadline first (EDF) order. For such a model, the distribution of the current lead times of the fluid mass on each route coincides with the fluid arrival measure for this route, truncated below on the current frontier level. Locally edge minimal fluid models may be regarded, in some sense, as fluid counterparts of EDF resource-sharing networks. Under mild assumptions, a locally edge minimal fluid model is uniquely determined by its data. We also show stability of such models in the strictly subcritical case. More generally, each such a subcritical model converges to the invariant manifold in finite time.

More than Pus – Primary Hepatic Epithelioid Angiomyolipoma Masquerading as Liver Abscess

Hepatic angiomyolipomas (AML) are rare mesenchymal tumours of which the epithelioid type is a rare type with malignant potential. We report a case of primary hepatic epithelioid angiomyolipoma masquerading as liver abscess. A 46-year-old man presented with a 5-day history of fever with epigastric pain and nausea. On the night of admission, his temperature spiked to 39°C, his blood pressure was 135/79, his heart rate 98, his liver function test revealed albumin 37 g/L, bilirubin 25 μmol/L, ALP 298 U/L, ALT 247 U/L, and AST 344 U/L. The clinical suspicion was hepatobiliary sepsis and intravenous ceftriaxone was commenced. CT of the abdomen showed an ill-defined hypodense focus in segment 4A/8 (4.5 × 3.5 cm) with a minimal fluid component implying a developing abscess or phlegmon. The images were reviewed by a radiologist and showed minimal fluid for percutaneous drainage. MRI of the liver was performed to further characterize the lesion and revealed a solid mass with nodular areas of arterial enhancement and washout, suspicious of neoplasm. Ultrasound-guided liver biopsy of the lesion was performed. Histology showed a histiocyte-rich epithelioid neoplasm consistent with the epithelioid variant of AML. Immunohistochemical staining was positive for human melanoma black 45, melan-A and cluster of differentiation 68. He successfully underwent liver resection of segment 4A/8 after 6 weeks of antibiotics. To our knowledge, this is the first reported case in the literature of primary hepatic epithelioid angiomyolipoma masquerading as liver abscess.

Experimental Investigation of Soyabean Oil Based Cutting Fluid during Turning of Hardened AISI 4340 Steel with Minimal Fluid Application

Turning of hardened steel is normally carried out with copious supply of cutting fluid to improve the cutting performance. Most of the cutting fluids in regular use are petroleum based emulsions which create several environmental problems. In this context, pure dry turning is a logical alternative as it is free from the problems associated with the cutting fluid. The achievable tool life and part finish are often affected while machining under completely dry condition. Under such situation, the concept of minimal cutting fluid application (MCFA) presents itself as a possible solution. In this study an effort was made to study the effect of soya bean oil based cutting fluid on cutting performance with minimal cutting fluid application during turning of hardened AISI4340 steel. An 18 run experiment was designed using Taguchi technique to study the effect of fluid application parameters on cutting temperature and surface roughness. Improvement in cutting performance was observed in terms of reduction in cutting temperature and improvement in surface finish (Ra) when water in oil emulsion of soya bean oil was used as the cutting fluid.