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Enhanced natural gas recovery (EGR) with supercritical (sc)CO2 sequestration offers the prospect of increased natural gas recovery. High-fidelity reservoir simulations offer a method to quantify the risk of contamination of produced gas by the injected scCO2. Simulations of scCO2 mixing with the reservoir gas have been reported; however the effects of connate water on EGR have not been effectively explored. We extend a prior EGR simulation tool (Patel, May and Johns, 2016; Ref. [1]) to incorporate connate water accounting for its effect on dispersivity and permeability; chemical equilibrium is modelled using a novel, computationally efficient Lagrange multiplier-based approach. The code is applied to a ‘quarter five-spot’ benchmark scenario. The inclusion of connate water generally resulted in a reduction in breakthrough time and a decrease in methane recovery. The connate water's largest effect was to change the scCO2 flow field, which sank towards the reservoir floor, flooded the lowermost accessible layers and entered the production well via a high throughput channel (‘coning’). The magnitude of these effects were, however, sensitive to well perforation depth, the influence of which was subsequently studied systematically. Well perforation depth was found to determine the duration of these sinking and coning events in a non-linear manner.

EGR (Enhanced natural gas recovery) with CO2 sequestration offers the prospect of significant environmental and economic benefits by increasing gas recovery while simultaneously sequestering the greenhouse gas. Field-scale deployment is currently limited as the risks of contamination of the produced gas by injected CO2 are poorly understood. Reservoir simulations offer a method to quantify the risk but only if sufficiently accurate. For the first time, finite element simulations are presented for several EGR scenarios that incorporate the most accurate models available for fluid mixture and rock properties. Specifically, the GERG-2008 EOS (equation of state) is utilised to describe the supercritical fluid mixture's density, as are reference correlations linked to the most accurate experimental data available for diffusivity and viscosity. Realistic values for rock dispersivity and tortuosity determined from high-accuracy core-flooding and NMR (nuclear magnetic resonance) experiments were also integrated. The relative impacts of these properties were investigated for a benchmark layered reservoir with a quarter 5-spot well pattern. Recovery efficiency at different CO2 injection rates was also investigated and was determined to be the dominant consideration: a 100-fold rate increase improved recovery from 53% to 69% while CO2 breakthrough time decreased by less than expected. Collectively, these results emphasise the importance of accurate reservoir simulations for EGR.

Extensive movement of the liquid phase relative to the solids in solid–liquid pastes during extrusion forming is an undesirable process phenomenon. The impact of formulation and flow pattern on liquid phase migration (LPM) during extrusion of model pharmaceutical pastes (40–50 wt% microcrystalline cellulose/water) has been investigated by ram extrusion through square-entry and 45° conical-entry dies, and by lubricated squeeze flow (extensional flow). Threshold velocities for LPM were observed in both configurations. Squeeze flow testing showed that dilation during extension can cause LPM, while ram extrusion featured both dilation effects and drainage due to compaction. The threshold velocities observed in the two configurations agreed when presented as characteristic shear rates. The threshold velocity increased with paste solids content.

Petroleum based mineral insulating liquid has being used for a long long time as transformer oil. As there are limited reserves of precious petroleum, the search is on for an alternate suitable synthetic liquid. An effort has been made to evaluate LAB (linear alkyl benzene) as per relevant standard specification (IS: 335-1993) for a new transformer oil. It is observed that it also conforms to the requirements of equivalent international standards e.g., LEC 296, BS 148, ASTM D 3487. This is also compatible with different construction materials of transformer as well as mineral insulating oil in service. Significant improvement in pour point and ageing characteristics of indigenous paraffinic transformer oil is observed due to blending of LAB. The lower gassing tendency of LAB makes it a good substitute as a capacitor impregnant. There is a need to conduct long term ageing studies and field trials to ensure its reliability as a liquid dielectric.

Chapattis are a staple in the diet of people living in the sub-continent of India. They are widely made using atta flour in homes and in small scale industries. Atta is flour obtained by grinding wheat grown in the Indian sub-continent. Atta dough is made by mixing flour with only salt and water. It is rolled into circular disks and baked on open hot stoves. High quality chapattis puff during baking and remain soft and pliable over a considerable period of time. Attempts to make chapattis of the same quality have been made in countries outside of the Indian sub-continent using local flours. However, it has not been possible to produce products of a similar quality. The same issue of quality – sub-standard puffing and texture, has also hindered fortifying atta by adding nutrition-rich additives, like pulse flours. A project was carried out in our laboratory comparing quality of chapattis made with Indian atta with those made with local wholemeal flour (WW), mixes of local wholemeal flour (L+WW) and lupin flour and 100% lupin flour. Lupin is a legume, high in protein and fibre with no starch. Having no gluten, lupin dough lacks extensibility. All chapattis made from these four different flours, including those made with 100% lupin dough, puffed fully. Qualitatively, the quality of chapattis made with atta was equivalent to those made with the mix of lupin flour and WW flour. To understand these surprising results, doughs were characterized by measurement of true rheological properties and by image analyses of pore structures in doughs using a Skyscan CT scanner. Results showed that atta dough was more porous and retained more elasticity and porosity compared to other doughs. Dough extensibility was not a requirement for puffing of chapattis. These results provide new methods for characterizing atta dough quality and methods to guide addition of additives atta to improve nutritional profiles.