Browsing by Author "Archibong-Eso, Archibong"

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    Discharge coefficient of high viscosity liquids through nozzles
    (Elsevier, 2019-01-03) Essien, S.; Archibong-Eso, Archibong; Lao, Liyun
    Experimental investigation on discharge coefficient, Cd, for high viscosity fluid through nozzles was carried out. The viscosity of the fluid used for the test ranged from 350 to 1500 mPa s. The length-to-diameter ratio of the nozzle, l/d and the ratio of nozzle diameter to pipe diameter ratios β were used to investigate the influence of geometry on Cd. Results show a significant dependence of Cd on Re, l/d and β ratio. An empirical correlation on the discharge coefficient was developed based on the data from this study which was also compared with data from other published studies. This correlation, with an R-squared value of 0.9541, was valid for nozzle sizes 10–20 mm and for Re between 1 and 200. Cd values obtained from experimental data, and those from the empirical correlation were compared, and a mean standard deviation of 0.0231 was obtained.
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    Estimating slug liquid holdup in high viscosity oil-gas two-phase flow
    (Elsevier, 2018-10-29) Archibong-Eso, Archibong; Okeke, Nonso Evaristus; Baba, Yahaya D.; Aliyu, Abdulkabir; Lao, Liyun; Yeung, H.
    Slug flow is one of the most critical and often encountered flow patterns in the oil and gas industry. It is characterised by intermittency which results in large fluctuations in liquid holdup and pressure gradient. A proper understanding of its parameters (such as slug holdup) is essential in the design of transport facilities (e.g. pipelines) and process equipment (slug catchers, separators etc.). In this paper, experimental investigation of slug liquid holdup (defined as the liquid volume fraction in the slug body of a slug unit) is performed. Mineral oil with viscosity, μ=−0.0043T3+0.0389T2−1.4174T+18.141 and air were used as test fluids. A 0.0254 m and 0.0762 m pipe internal diameters facilities with pipe lengths of 5.5 and 17 m respectively were used in the study. Electrical Capacitance Tomography was used for slug holdup measurements. Results obtained in the study shows that slug liquid holdup varied directly as the viscosity and inversely as the gas input fraction. Existing slug holdup correlations and models in literature did not sufficiently predict present experimental results. A new empirical predictive correlation for estimating slug liquid holdup was derived from present experimental databank and from data obtained in literature. The databank's liquid viscosity ranges from 0.189 – 8.0 Pa.s. Statistical analysis of the new correlation vis-à-vis existing ones showed that the present correlation gave the best performance with an average percent error, E1; absolute average percent error, E2 and standard deviation, E3 of 0.001, 0.05 and 0.07 respectively, when tested on the high viscosity liquid–gas databank.
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    Prediction of entrained droplet fraction in co-current annular gas–liquid flow in vertical pipes
    (Elsevier, 2017-03-07) Aliyu, A. M.; Almabrok, Almabrok Abushanaf; Baba, Yahaya D.; Archibong-Eso, Archibong; Lao, Liyun; Yeung, Hoi; Kim, K. C.
    The entrained droplet fraction is an important parameter in annular two-phase flow, as its correlations are key inputs in flow simulation codes for the prediction of pressure drop and critical heat flux or dryout. Investigators have stressed the importance of extending the validity range of current correlations so that more conditions are covered. This could be achieved for example by including fluids with higher viscosities, a wider range of operating pressures, and increase in the size of pipes used for experiments (most of the data in the literature are from pipes of 50 mm diameter and below). In attempt to improve the latter, experiments were conducted in a 101.6 mm gas–liquid flow loop at Cranfield University’s Oil and Gas Engineering Laboratory and data on the fraction of droplets were collected in the annular flow regime by measuring the film velocity, from which the droplet fraction was calculated. Comparison of the film velocity by this method and by a mass balance showed close agreement. A capacitance Wire Mesh Sensor was used for flow visualisation in order to distinguish between annular and churn flow. In order to arrive at an improved correlation, over 1300 data points were gathered from other published works. These include air–water studies where large pipes of up to 127 mm in diameter were used. The others were from small-diameter pipes and for refrigerant, steam–water, air–water, and air–glycerine flows. Since in the annular regime, the gas flow entrains liquid droplets into the core, their presence alters the properties of the gas core. Therefore, accurate predictions are pivotal for the energy efficient design and operation of facilities in the petroleum and nuclear power industry. The correlation obtained here showed good agreement with the collected databank.
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    Sand minimum transport conditions in gas–solid–liquid three-phase stratified flow in a horizontal pipe at low particle concentrations
    (Elsevier, 2019-01-15) Fajemidupe, Olawale T.; Aliyu, Aliyu M.; Baba, Yahaya D.; Archibong-Eso, Archibong; Yeung, Hoi
    Sand production in the life of oil and gas reservoirs is inevitable, as it is co-produced from reservoirs. Its deposition in petroleum pipelines poses considerable risk to production and can lead to pipe corrosion and flow assurance challenges. Therefore, it is important that pipe flow conditions are maintained to ensure sand particles are not deposited but in continuous motion with the flow. The combination of minimum gas and liquid velocities that ensure continuous sand motion is known as the minimum transport condition (MTC). This study investigates the effect both of sand particle diameter and concentration on MTC in gas/liquid stratified flow in a horizontal pipeline. We used non-intrusive conductivity sensors for sand detection. These sensors, used for film thickness measurement in gas/liquid flows, were used for the first time here for sand detection. We found that MTC increases with increase in particle diameter for the same concentration and also increases as the concentration increases for the same particle diameter. A correlation is proposed for the prediction of sand transport at MTC in air–water flows in horizontal pipes, by including the effect of sand concentration in Thomas’s lower model. The correlation accounts for low sand concentrations and gave excellent predictions when compared with the experimental results at MTC.
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    Slug length for high viscosity oil-gas flow in horizontal pipes: experiments and prediction
    (Elsevier, 2018-02-08) Baba, Yahaya D.; Aliyu, Aliyu M.; Archibong-Eso, Archibong; Abdulkadir, Mukhtar; Lao, Liyun; Yeung, Hoi
    An experimental investigation was carried out on the effects of high liquid viscosities on slug length in a 0.0762-m ID horizontal pipe using air-water and air-oil systems with nominal viscosities ranging from 1.0 to 5.5 Pa s. The measurements of slug length were carried out using two fast sampling gamma densitometers with a sampling frequency of 250 Hz. The results obtained show that liquid viscosity has a significant effect on slug length. An assessment of existing prediction models and correlations in the literature was carried out and statistical analysis against the present data revealed some discrepancies, which can be attributed to fluid properties in particular, low viscous oil data used in their derivation Hence, a new high viscous oil data presented here from which we derive a new slug length correlation was derived using dimensional analysis. The proposed correlation will improve prediction of slug length as well as provide a closure relationship for use in flow simulations involving heavy oil. This is important since most current fields produce highly viscous oil with some reaching 10 Pa s.
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    Slug translational velocity for highly viscous oil and gas flows in horizontal pipes
    (MDPI, 2019-09-12) Baba, Yahaya D.; Archibong-Eso, Archibong; Aliyu, Aliyu M.; Fajemidupe, Olawale T.; Ribeiro, Joseph X. F.; Lao, Liyun; Yeung, Hoi
    Slug translational velocity, described as the velocity of slug units, is the summation of the maximum mixture velocity in the slug body and the drift velocity. Existing prediction models in literature were developed based on observation from low viscosity liquids, neglecting the effects of fluid properties (i.e., viscosity). However, slug translational velocity is expected to be affected by the fluid viscosity. Here, we investigate the influence of high liquid viscosity on slug translational velocity in a horizontal pipeline of 76.2-mm internal diameter. Air and mineral oil with viscosities within the range of 1.0–5.5 Pa·s were used in this investigation. Measurement was by means of a pair of gamma densitometer with fast sampling frequencies (up to 250 Hz). The results obtained show that slug translational velocity increases with increase in liquid viscosity. Existing slug translational velocity prediction models in literature were assessed based on the present high viscosity data for which statistical analysis revealed discrepancies. In view of this, a new empirical correlation for the calculation of slug translational velocity in highly viscous two-phase flow is proposed. A comparison study and validation of the new correlation showed an improved prediction performance.