The water-soluble polymer PAM (polyacrylamide) is used in enhanced oil recovery (EOR) operations. It is pumped into water injection wells to increase the viscosity of the injected water and in turn to direct more oil towards production wells. This EOR process is proven to be sensitive to operational well conditions such as hydrocarbon reservoir temperature, as well as the salinity of the injected water and/or formation water. These operational conditions lead to technical challenges ranging from the solubility of PAM in injection water to the behaviour of PAM inside the reservoir. To gain a clear picture of the functionality of PAM in EOR applications, this report characterizes its behaviour of in terms of degree of hydrolysis and changes in solution viscosity determined using Perkin Elmer spectrum 100 Fourier transform infrared-Attenuated total reflection (FTIR)-ATR and nuclear magnetic resonance spectroscopy (¹H NMR) and a Fann model 35 Couette and Cole Parmer rotational viscometer, respectively. Different shear rates were investigated to determine the effect of shear on PAM gel stability. Experiments were performed for PAM mixed with formation brine at 50, 70, and 90 °C for ageing times of up to 30 days. The results indicate that the degree of hydrolysis achieved after 30 days is much higher in saline solutions than in pure water, and that this effect is more pronounced at higher temperatures. For example, after 30 days at 50 °C, the hydrolysis level was observed to be 53%, rising to 65% at 70 °C and 75% at 90 °C in PAM mixed with brines. Similar trends were observed with viscosity, where lower viscosity was observed for samples at higher temperatures and salinities. It is thus reasonable to conclude that the degree of hydrolysis causes changes in the viscosity of the polymer gel, leading to a decline in its performance as it ages.

Polyacrylamides (PAM) are widely used as water-soluble polymers producing gel in oil reservoirs to assist in oil extraction from reservoirs with high levels of heterogeneity. These gels are susceptible to degradation due to hydrolysis in harsh reservoir conditions such as elevated temperature and salinity. This study uses a polymer integration technique in attempting to optimize the performance of PAM in the enhanced oil recovery process for reservoirs with high temperature and salinity. The results show that, at high temperature, hydrolysis is suppressed and gel stability is maintained via the addition of Polyvinylpyrrolidone (PVP) to PAM solutions. The optimum composition was identified as being 20/80 wt% PAM: PVP for oilfield operations at 90 °C and a moderate salinity of 43,280 ppm. The degree of hydrolysis at 30 days was suppressed from 75% to 29.9%, with associated increases in viscosity from 11 to 38.2 mPa.s and from 18 to 44.3 mPa.s corresponding to rotational speeds of 30 and 10 rpm respectively. The issue of high salinity was considered by increasing the salinity of the optimised PAM: PVP mixture to 200,000 ppm. Under these conditions the degree of hydrolysis of the optimised solution increased from 29.9 to 46.9% and viscosity decreased from 38.2 to 28.6 and from 44.3 to 40.4 mPa.s for rotational speeds of 30 and 10 rpm respectively. 2-Acrylamido-2-MethylpropaneSulfonic acid (AMPS) was added to the mix to try to improve temperature stability. It was observed that, with an optimum composition of 18/72/10 wt% PAM:PVP:AMPS, the degree of hydrolysis decreased to 22% with viscosity levels of 30.6 and 22.8 mPa.s corresponding to rotational speeds of 10 and 30 rpm respectively.

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

The objective of this work is to present a novel geometrical configuration for microbubble generators (MBGs) to improve dissolved‐oxygen levels in water. Among various methodologies from the literature, Orifice and Venturi tubes have been considered as baseline cases. Experimental data from the literature are used to verify a computational fluid dynamics (CFD) case developed for a better understanding of the dynamics of MBGs. As a result, the validated CFD setup has been implemented on a modified Venturi‐type generator, where air is injected coaxially with respect to the tube axis, whereas a helicoid wall at variable pitch angle is used. Results show a reduction in the mean bubble diameter distribution from the baseline Venturi tubes, particularly, at low‐speed inlet velocities. This is of interest, especially to decrease the energy requirement for most common water aeration systems.

The effect of Aspect ration on melting process of PCM (polyethylene glycol 1500 (PEG 1500)) in a rectangular encloser was investigated using CFD modelling. The CFD model was validated by experimental measurement performed for one case of aspect ratio of 2.31 with height = 155 mm, width = 67 and depth = 200 mm. The study was conducted in two phases: i) constant height enclosure, ii) constant volume enclosure. The main conclusions from this study are: i) the conduction heat transfer is the only mode of heat transfer in the first 250 secs from the start of heating of PCM. Then, the evolution of natural circulation starts at the hot wall and developed to a complete steady cycle after 2000 secs. ii) the results indicate a clear effect of the aspect ratio (AR) on melting percentage with peak at AR = 2,31 for both cases of constant heght and constant volume. iii) the results also show that there is a limiting width of the encloser where the circulation velocity reduced to low values (<0.3 mm/s) regardless of the enclosure heht.