Semi-Empirical Model to Estimate the Solubility of CO2 NaCl Brine in Conditions Representative of CO2 Sequestration

Peer reviewedPublisher PD

The effects of controlling parameters on polymer enhanced foam (PEF) stability

In the present study, four surfactants including AOS, SDS, SDBS, and TX100 were used as the foaming agent and a PHPA polymer with relatively low to high concentrations was added to the solutions prepared in both fresh water and 8 wt. % NaCl. Also, paraffin and vaseline oils with different viscosities were used to investigate the effect of oil on PEF stability. Polymer addition to foam can effectively improve foam stability compared with conventional foam stability. In addition, the polymer concentration increase could lead to foam stability increase; thus, the maximum polymer concentration in solutions could produce the most stable foam. Solutions with 8 wt. % NaCl had destabilizing effect, that is, unlike solutions with fresh water, it slightly reduced foam stability. Contacted oil in the solutions could substantially reduce foam stability. Also, the destabilizing effect was more severe with paraffin oil rather than vaseline oil. Of all the four surfactants used in this research, SDS had the highest compatibility with PHPA and produced the most stable foam, while AOS, SDBS, and finally TX100 surfactants were in next orders. In addition, microscopic photos showed that the type of solution has a significant effect on bubble size and foam stabilit

Application of a novel green nano polymer for chemical EOR purposes in sandstone reservoirs: Synergetic effects of different fluid/fluid and rock/fluid interacting mechanisms

In this research, a novel natural-based polymer, the Aloe Vera biopolymer, is used to improve the mobility of the injected water. Unlike most synthetic chemical polymers used for chemical-enhanced oil recovery, the Aloe Vera biopolymer is environmentally friendly, thermally stable in reservoir conditions, and compatible with reservoir rock and fluids. In addition, the efficiency of the Aloe Vera biopolymer was investigated in the presence of a new synthetic nanocomposite composed of KCl-SiO2-xanthan. This chemically enhanced oil recovery method was applied on a sandstone reservoir in Southwest Iran with crude oil with an API gravity of 22°. The Aloe Vera biopolymer’s physicochemical characteristics were initially examined using different analytical instruments. The results showed that the Aloe Vera biopolymer is thermally stable under reservoir conditions. In addition, no precipitation occurred with the formation brine at the salinity of 80,000 ppm. The experimental results showed that adding ethanol with a 10% volume percentage reduced interfacial tension to 15.3 mN/m and contact angle to 108°, which was 52.33 and 55.56% of these values, respectively. On the other hand, adding nanocomposite lowered interfacial tension and contact angle values to 4 mN/m and 48°, corresponding to reducing these values by 87.53 and 71.42%, respectively. The rheology results showed that the solutions prepared by Aloe Vera biopolymer, ethanol, and nanocomposite were Newtonian and fitted to the Herschel-Bulkley model. Finally, core flooding results showed that the application of a solution prepared by Aloe Vera biopolymer, ethanol, and nanocomposite was effective in increasing the oil recovery factor, where the maximum oil recovery factor of 73.35% was achieved, which could be attributed to the IFT reduction, wettability alteration, and mobility improvement mechanisms

A mechanistic model to predict pressure drop and holdup pertinent to horizontal gas-liquid-liquid intermittent flow

In this work a mechanistic model is proposed to predict pressure drop and phase holdup for viscous oil-water-gas flows within horizontal duct. The model is suitable for three phase intermittent (slug) flows where oil and water phases are fully mixed. However, validation is also made for slug flow with core-annular oil and water flow. This approach makes use of a correlation for total slug unit length developed by Babakhani Dehkordi (2017) as an input in the model so that the continuity equation is explicitly solved, reducing complexity of the present models in the literature survey. Furthermore, oil and water are assumed to have a homogeneous behavior to simplify three-phase flow equations. The model predictions are compared with experimental data of viscous oil-water-gas slug flows. Results revealed that inclusion of slug unit data together with assumption of homogeneous flow for oil and water in mechanistic model improved prediction of pressure drop over the range of investigated flow conditions

Mineral carbonation of red gypsum via pH-swing process: Effect of CO2 pressure on the efficiency and products characteristics

The objective of this study was to investigate the feasibility of indirect carbonation of red gypsum through pH swing process. The effect of CO2 pressure as one of the major controlling parameters in carbonation process was investigated in details. The dissolution of red gypsum was performed using 2M H2SO4 at 70°C for 60min reaction time. The pH was regulated using NH4OH, which also precipitated out the impurities from the solution. Finally, the calcium rich solution was poured in an autoclave reactor and CO2 was injected into the reactor for carbonate precipitation. The experimental results showed that the Fe, the main impurity can be effectively separated prior to carbonation stage (92-95%). At low pH the Fe was separated while at high pH Ca was precipitated as carbonate. The carbonation efficiency was directly affected by the CO2 pressure and the maximum efficiency (100%) was achieved when 8bar CO2 pressure was used. In addition, carbonation experiments resulted in CaCO3 production in the form of calcite, aragonite, and vaterite with 98% purity

The effect of ultrasonic waves on oil viscosity

This study presents the development of a technique to directly investigate the effect of ultrasonic waves at 25 and 68 kHz and 100, 250, and 500 W on the viscosity of paraffin, synthetic oil, and kerosene. Experiments were performed under both controlled and uncontrolled temperature conditions in a smooth capillary tube. The results indicate that the viscosity of the liquids decreases upon exposure to ultrasound and may be attributed to induced heat generation and cavitation within the fluid. The specifics of ultrasound frequency, power, and temperature on viscosity reduction are discussed and interpreted

Study of viscous oil-water-gas slug flow in a horizontal pipe

Slug flow characteristics for viscous oil-water-air are experimentally conducted in a horizontal pipe with a 40 mm ID and 12 m long. Results of experimental pressure gradient are presented, taking into account μo = 0.83 Pa s. Water and air superficial velocities ranged 1.02–2.1 m s−1 and 0.22–1.9 ms−1, respectively. Flow patterns were observed and images captured by using a video camera. New data-sets on such flow that include translational bubble velocity, slug and elongated bubble length, total slug unit length and frequency are experimentally provided. Translational velocity of slug units is measured by means of optical probes and video camera, and compared with modified Nicklin (1962) correlation. Moreover, slug body, elongated bubble and slug unit lengths are measured by optical probe. Statistical analysis was adopted based on measured data of slug length to develop probability density function (PDFs). As a result, a new expression to compute slug unit length in terms of liquid, gas superficial velocities, and pipe diameter was proposed