Department of Chemical & Petroleum Engineering

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    Open Access
    The Application of Peng Robinson Equation of State to Predict Natural Gas Behaviour in Oil based Drilling Fluid
    (Department of Civil and Environmental System Engineering, University of Benin., 2008-06) Adeyanju, Olusiji; Olafuyi, Olalekan
    A major problem associated with the use of oil base drilling fluid is the increased difficulty of detecting gas which enters the borehole and dissolves in the drilling fluid. Previous authors have made computer-simulated comparisons between a water-base and an oil-based drilling fluid for one specific field example. However, a method is needed that will permit field personnel to quickly estimate the amount of dissolved gas that can be associated with an observed pit gain for the field conditions present. . In this paper, methods were presented for estimating the swelling of oil based drilling fluid due to dissolved gas. This involves the determination of the formation volume factors of the fluids (oil-gas-drilling fluid mixture) at given subsurface conditions using Peng-Robinson equation of state and hence the detection of the natural gas intrusion into a given well and subsequent calculation of the pit gains. The results were compared with similar but empirically obtained data. The pressure profile for a well at given conditions have also been made thereby aiding the several predictions that will lead to proper fluid flow control.
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    Open Access
    Attenuating Severe Slug Flow at Large Valve Opening for Increased Oil Production Without Feedback Control Signal
    (Elsevier B.V, 2016) Ehinmowo, A.B; Orodu, O.D; Anawe, P.A; Ogunleye, O.O
    In the co-current flow of gas-liquid mixtures through pipeline-riser system, severe slugging is frequently encountered and manifests in significant fluctuation of flow and pressure. This can pose serious threat to production facilities. The most common method for its mitigation is by choking which unfortunately could negatively affect production. The objective of this study therefore is to develop a technique that can help stabilise the system and maximise production simultaneously. In this paper, a new general method for multiphase flow system stability analysis was proposed based on a new passive attenuation method – the intermittent absorber. A series of experiments were carried out in a 4″ pipeline-riser system which is 55 m long with horizontal pipe inclined at 2° connected to 10.5 m high catenary riser followed by 3 m horizontal topside section. Air and water were used as experimental fluids. Numerical studies were also conducted on a 4″ pipeline-riser system to proof the concept. The results showed that the intermittent absorber possess potential for stabilising severe slug flow at larger valve opening and lower pressure. For the case studied, up to 9% reduction in the riser base pressure was reported which practically implies increased oil production.
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    Open Access
    Automation of a Dust Sampling Train.
    (Journal of Modelling, Design and Management of Engineering Systems,, 2007) Akinola, A. A.; Muir, D. M.
    The accuracy of measuring the concentration of particulate matter in flue gas streams by a dust sampling train can be significantly improved or minimized by automating the sampling process using a microprocessor based system. Two situations are presented here, in which a dust sampling train is interfaced via appropriate transducers with a microprocessor and additional circuit boards. The results obtained from this work show that the flue gas sampling process can be automated using a microprocessor-based control system and a sampling train. Using the sampling train developed by the British Coal Utilization Research Association (BCURA) with both the internal and external flow-meter arrangements, the maximum error in iso-kinetic sampling velocity throughout the sampling period did not exceeding 5%.
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    Open Access
    Computational Accuracy in Calculating In-Duct Iso-Kinetic Sampling Rates in A Sampling Train Using a Microprocessor
    (Journal of Engineering Research, 2011-09) Akinola, A. A.
    The microprocessor is the heart of many automated devices in use at the present time. These microprocessors are used mainly in devices where repeated and rapid rates of calculations are required. To achieve' rapid rates of calculation, the microprocessor is programmed directly in machine or assembly language. This paper presents the results of work done in programming a microprocessor in the Assembly programming language to calculate iso-kinetic sampling rates in a dust sampling train. The accuracies of the calculation are examined by comparing the results of the calculations with those obtained when using a mainframe computer. The results show that the accuracy of the calculations is within -4.5 %and +2.5%
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    Open Access
    Computer Aided Design of Circular Clarifiers,
    (Journal of the Nigerian Society of Chemical Engineers, 2013) Odediran, E. T.; Ayo, D. B.; Akinola, A. A.
    An algorithm was developed for the design of primary circular clarifier for Wastewater treatment. Three computer programs were developed using Microsoft Excel, FoxPro and MATLAB respectively, all based on the algorithm. Computational Results from the three programs were not significantly different from those carried out manually. The algorithm was validated by feeding operational data (influent and effluent conditions) from the Primary clarification unit of the City of Springfield Wastewater Treatment Plant (WWTP), Ohio, USA into the three computer programs. The results of calculations from the computer programs using data from the Springfield WWTP were not significantly different from the design data of the WWTP.
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    Open Access
    Cyber-Security Evaluation for a Hypothetical Nuclear Power Plant using the Attack Tree Method
    (Journal of Physical Security, 2015) Akinola, A. A.; Kuye, A. O.; Ayodeji, A
    The widespread introduction of digital network systems in nuclear power plants has increased such infrastructures vulnerability to cyber-attacks. The attack tree approach to evaluate and analyze cyber-attacks quantitatively, in a nuclear power plants’ network system is presented in this work. Information on a hypothetical nuclear power plants’ network system was used to build attack trees that show different attack paths that external adversaries can use to compromise the network system. To assert the ease or difficulty of compromising each attack tree, numerical values are assigned to the leaf nodes of each attack tree. The return on attack for each intermediate node and the root node are then calculated. This calculation is done by randomly varying the vulnerability values of the leaf nodes within the designated range. On observing high return of attack values with the two attack trees developed, countermeasures were then implemented. Modified network systems were constructed and the return on attack recalculated. The return on attack (ROA) values for the nodes were observed to decrease, after implementing the countermeasures on the network security systems.
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    Open Access
    Dehydration and Rehydration Characterization of Yam (Dioscorea Rotundata) Tuber Slices Using a Refractance WindowTM Dryer,
    (Zimbabwe Journal of Science & Technology, 2017) Akinola, A. A.; Shittu, A. S.; Ezeorah, S. N.
    The effect of slice thickness on the dehydration and rehydration characteristics of yam was studied in a Refractance Window TM (RW) type dryer constructed from a laboratory water bath. Yam slices 1.5, 3.0 and 4.5 mm thick were dried in a laboratory scale RW dryer where the water in the bath was maintained at temperature of 80 °C. The initial moisture content of the yam samples was 69% on a wet basis (wb). The drying process was carried out until the final moisture content of the product was below 10% (wb). The experimental data indicate that the drying time decreases rapidly as the yam slices decrease; the 1.5 mm, 3.0 mm and 4.5 mm thick yam slices, dried to below 10% within 40 minutes, 80 minutes and 120 minutes respectively. The experimental data indicated that the drying kinetics for the yam slices fitted the Haghi and Ghanadzadeh thin-layer drying model with a regression coefficient exceeding 99.9 % for the 1.5, 3.0 and 4.5 mm thick slices. The rehydration ratio increased to a steady value of about 1.91 when soaked in water for about 180 minutes.
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    Open Access
    Dehydration Characterization of Carrot (Daucus Carota) Slices Dried Using the Refractance Window™ Drying Technique
    (Zimbabwe Journal of Science & Technology, 2016) Akinola, A. A.; Malomo, T. O.; Ezeorah, S. N.
    The drying characteristics of yellow carrots (Daucus Carota) were studied using a laboratory scale batch Refractance Window™ (RW) dryer. This study was performed to facilitate the understanding of the design on a continuously operating RW dryer, by studying the drying characteristics of a batch RW drying process. A dryer was constructed by modifying a laboratory water bath. The bath is covered with a transparent Polyethylene terephthalate (PET) plastic film that has a drying area of 10 cm by 10 cm. 3 mm thick slices of carrots were dried on the Refractance WindowTMdryer, and the variation of the moisture content of the slices was measured during the drying process. The water temperature beneath the plastic film was maintained at 60 oC. From the experimental data the drying curves, the drying rate curves and the Krischer curves were plotted. The thin layer mathematical drying model that describes the drying kinetics of the drying data was determined. The bulk density of the powdered carrots and the variation of the rehydration ratio of the carrot slices with time was determined. The effective moisture diffusivity of the carrots is also estimated. Observations indicate that the carrot slices dried to below 10% moisture content on a dry basis in about 200 minutes. Regression analysis suggests that the Haghi and Ghanadzadeh model best describes the drying behaviour for the 3 mm thick slices with a coefficient of determination (R2) value of 0.999 for the 17 models studied. The Rehydration Ratio of the carrot samples varied from 2.457 to 4.126 with rehydration times of 10 to 60 minutes. An average bulk density value of the carrot powder samples was 0.8625 grams/ml. The effective moisture diffusivity of the 3 mm thick carrot slices was determined to be 7.29513×10-8 m2/s.
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    Open Access
    Dehydration Kinetics of Cassava, Yam and Potato Slices Using a Refractance WindowTM Dryer
    (FUOYE Journal of Engineering and Technology, 2018) Akinola, A. A.; Ezeorah, S. N.
    This study aims to investigate the drying characteristics of cassava, yam, and potato slices using a laboratory scale batch Refractance Window™ (RW) dryer. The experimental dryer was constructed by modifying a laboratory water bath. The bath was covered with a transparent Polyethylene terephthalate (PET) plastic film held in-place with angled edges. The cassava, yam, and potato slices were dried on the Refractance WindowTM dryer, and the variation of the moisture content of the slices during the drying process was measured. The water temperature beneath the plastic film was maintained at 60°C. The dehydration data were fitted to thin-layer drying models. Regression analysis suggested that the Haghi and Ghanadzadeh model best describes the dehydration behaviour for the 3 mm thick slices for the cassava, yam, and potato tubers. The coefficient of determination (R2) values of 0.999, 0.998, and 0.998 for the cassava, yam, and potato slices respectively were reported in all the models studied. The drying curves, the drying rate curves, and the Krischer curves, from the experimental drying data, was plotted. Observations indicate that the cassava, yams, and potatoes slices dried to below 0.11 g water/gsolid moisture content in about 150 min. This study was performed to facilitate the understanding of the design, modelling, and operations of a continuously operating RW dryer.
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    Open Access
    Effective Moisture Diffusivity and Activation Energy Estimation of Cucumber Fruit Slices Using a Refractance WindowTM Dryer
    (Journal of The Association of Professional Engineers of Trinidad and Tobago, 2018) Akinola, A. A.
    This paper presents an estimation of the effective moisture diffusivities and the activation energy of cucumber fruit slices by studying the effect of temperature on the drying kinetics. A laboratory scale Refractance WindowTM dryer was used to obtain dehydration data for cucumber fruit slices. Experiments carried out on 3 mm thick cucumber fruit slices with water temperatures in the dryer at 65 oC (338K), 75 oC (348K) and 85 oC (358K) were performed. The experimental drying data were fitted to 8 thin layer drying models to select the most appropriate drying model. The Haghi and Ghanadzadeh model was determined to be the most suitable for the process conditions studied. Fick’s second law was used to calculate the effective moisture diffusivity. The moisture diffusion coefficient varied between 1.94 x 10-9 m2s-1 and 2.54 x 10-9 m2s-1 for the process conditions studied. The activation energy was estimated using the Arrhenius equation and for the given temperature range. The corresponding activation energy was calculated to be 13.55kJ/mol. A knowledge of the effective moisture diffusivities and activation energy of the cucumber fruit slices, when determined using the Refractance WindowTM drying technique will aid in understanding the design, analysis, and optimisation of such equipment for the drying of food.
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    Open Access
    Estimation of the Thermal Diffusivity of Beans Using a Simple Apparatus
    (FUOYE Journal of Engineering and Technology, 2019) Akinola, A. A.; Adeniji, O. B.
    A simple apparatus for the determination of the thermal diffusivity of black-eyed beans samples, using the transient heat conduction method is presented. This apparatus is a stainless steel cylindrical tube, containing the sample, placed into a constant temperature water bath. The variation of the temperature at the center of the tube with time is recorded. The thermal diffusivities were determined from the temperature-time relationship data of the sample, and the dimensions of the equipment. The estimated thermal diffusivity values of the samples varied between 4.70 x 10-8 to 6.94 x 10-8 and 5.26 x 10-8 to 7.68 x 10-8 when the temperature in the water bath was 50oC and 60oC, respectively. Also, the thermal diffusivity was higher when the water bath temperature was 60oC rather than 50oC for the sample range of particle sizes studied. As black-eyed beans are a staple food in many parts of West African, they are grown, harvested, and stored. The thermal diffusivity information is useful in determining the behaviour of this Argo-product when stored.
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    Open Access
    Evaluation of the Dehydration Characteristics of Ginger (Zingiber Officinale) Root Slices Using Refractance Window Drying Technology
    (FUOYE Journal of Engineering and Technology, 2018) Akinola, A. A.; Azeta, O; Ezeorah, S. N.
    This study investigates the drying characteristics of ginger (zingiber officinale) root slices using the Refractance Window™ drying technology. A laboratory-scale dryer was constructed by modifying a water bath. 3 mm thick ginger root slices were dried on the transparent Mylar PET plastic film that covered the bath, and the variation of the moisture content of the slices with time was determined as the drying progressed. A water temperature of 60 oC was maintained beneath the plastic film. Various drying kinetic data curves are plotted from the drying data and the thin layer model that best fits the drying data was determined. Observations indicated that the ginger root slices dried to a moisture content of 0.1g H2O/g solid on a dry basis in about 210 minutes. The regression analysis results showed that the Haghi and Ghanadzadeh thin layer model best describes the drying data for 3 mm sized slices with the coefficient of determination ( ) value of 0.9985. An effective moisture diffusivity of 8.99 x 10-8 m2/s was observed for the ginger root slices.
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    Open Access
    Evaluation of the Drying Kinetics of Cassava (Manihot Esculenta) Slices Using a Refractance WindowTM Dryer
    (Journal of Engineering Research, 2017) Akinola, A. A.; Ezeorah, S. N.
    The dehydration kinetics of cassava slices dried using a Refractance WindowTM, a novel contact surface drying technique, is presented in this study. The dryer was constructed by modifying a laboratory water bath. Cassava slices of 3 mm thick were dried on the Refractance WindowTM, and the moisture content of the slices was measured as the drying progressed. A water temperature between 75 – 80 oC was maintained beneath the plastic film. Drying curves were obtained from the drying data, and the thin layer model that best fit the drying data was determined. The bulk density and rehydration ratio of the dried cassava were determined. The cassava slices were observed to dry to about 5 % moisture content after 210 minutes. The regression analysis results showed that the Haghi and Ghanadzadeh thin layer model best described the drying data for 3 mm thick sized cassava slices. The Mean Bias Error (MBE), the Coefficient of Determination (R2), the Root Mean Square Error (RMSE) and the Chi-square (χ2) values were -8.83x10-6, 9984.34x10-4, 4.20x10-4 and 4.41x10-4 respectively. The Rehydration Ratio increased to a steady value of 3.17 in about 180 minutes.
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    Open Access
    Evaluations of the Effect of Selected Wax Inhibitive Chemicals on Wax Deposition in Crude Oil Flow in Sub-sea Pipe-Lines
    (Taylor & Francis Production, 2017-08) Adeyanju, Olusiji; Oyekunle, Layioye
    Comparative studies were made on the effect of different wax inhibitive chemicals on the wax deposition volume during crude oils flow in pipeline. Two crude oils from Ovhor and Jisike oil fields in the southern part of Nigeria were used in the study. The four identified chemicals: Alkyl sulphonates (wax dispersant), polyethylene (wax inhibitors/crystal modifier), acrylate ester copolymer (pour point depressant, PPD) and xylene (wax solvents) inhibit wax deposition to varying degree of between 14.6–44.9% for crude oil A, and between 21.6–41.4% for crude oil B when 1500 ppm of each chemical was mixed with the crude oil sample. The optimal wax inhibition formulation of polyethylene, xylene, acrylate ester polymer and alkyl sulphonate contains 40.4, 19.2, 27.6, 12.8% and 36.3,21.5, 25.8, 16.4% for crude oil A and B respectively. Applications of the optimal formulated mixtures of the above chemicals inhibit wax deposition by 58.9% and 62.4% for crude oil A and B respectively
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    Open Access
    Experimental Investigation of Hydrodynamic Slug Flow in Pipeline-Riser Systems
    (Research India Publications, 2016) Ehinmowo, A.B; Ogunbiyi, A.T; Orodu, O.D; Aribike, D.S; Denloye, A.O
    Activities in oil and gas industry have shifted deep offshore. There is therefore the need to envisage and accurately provide for flow assurance challenges that might be encountered throughout the life of a field. Slug flow is one of the flow assurance concerns confronting the industry. The objective of the study was to gain insight into the behaviour of hydrodynamic slug flow in pipeline-riser system. This understanding is needed for the development of appropriate slug control strategy. Experimental studies were conducted in a 2” pipeline-riser system and a 2” horizontal two-phase flow facility. Slug envelopes were developed for the pipeline-riser system, the vertical and the horizontal pipes. The results revealed three distinct slug flow behaviours. The first type of slug was formed in the horizontal pipeline and transported through the riser pipe nearly unchanged, the second type of slugs were formed in the horizontal pipe but also experience growth in the riser pipe while the third are slugs formed in the vertical pipe without the influence of the upstream horizontal pipe. There is therefore the need to develop appropriate slug control strategies based on the observed behaviour of the identified regions.
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    Open Access
    Experimental Investigation of Hydrodynamic Slug Mitigation Potential of an Intermittent Absorber
    (Elsevier B.V, 2016) Ehinmowo, A.B; Ogunleye, O.O; Orodu, O.D
    The need to handle hydrodynamic slugs in a more efficient way becomes important as oil and gas activities shift deep offshore. This study describes the use of a vessel coupled to the pipeline-riser system upstream of the first stage separator for hydrodynamic slug attenuation. The experiments were carried out in a 2 pipeline-riser system which comprises of a 40 m long horizontal pipe connected to a 11 m high vertical riser followed by a 3 m horizontal topside section. Air and water were used as experimental fluids. Bifurcation maps and slug attenuation index (SAI) have been used to quantify increase in oil production and the slug attenuation potential of this concept. The device was observed to reduce the pressure fluctuations characterising hydrodynamic slug flow up to 22%. The device also provides additional benefits of stabilising the flow at higher valve opening (choke setting) and lower pressure compared to traditional choking. This in practice translates to increase in oil production. Special case of hydrodynamic slugs which exhibit overchoking induced slugging (OIS) was also observed to be relatively attenuated by the introduction of the absorber.
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    Open Access
    Experimental Investigation of Limonene-based Environmental-Friendly Emulsion Drilling Mud
    (2017) Olaitan, O.M; Orodu, O.D; Ehinmowo, A.B
    The use of emulsion drilling mud in the oil and gas industry has gained wide acceptance. However, the disposal of drill cuttings and the waste of such emulsion drilling mud usually poses environmental concern. Hence, there is the need to seek oil from biodegradable sources as an alternative to the current conventional diesel oil which constitute environmental threat. In this study, limonene obtained from dried peel of sweet orange was used as the dispersed phase in the formulation of nanomodified emulsion drilling mud. A Design Of Experiment (DOE) approach was employed to investigate the extraction of limonene and the results analysed. Three different mud samples were formulated; the conventional water-based drilling mud, nano-modified emulsion drilling mud with diesel oil and limonene as the dispersed phase respectively. The rheological properties, density, sand content, PH and filtration loss of the formulated mud samples were tested and compared. The results of the experiment showed that the formulated nano-modified emulsion drilling mud with limonene as the dispersed phase followed Herschel-Bulkley rheological Model with low gel strength and yield point which aredesirable mud property for turbulent flow at low pump pressure for effective hole cleaning. Also, there is reduction in filtration loss and mud cake compared to the conventional water-based drilling mud which will lead to reduction in torque and drag, reduction in pipe sticking, reduction in hole enlargement and less bit balling.
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    Restricted
    Experimental Investigation of the Centrifugal Effect on Demulsification of Water in Crude Oil Emulsion
    (Nova Science Publishers, Inc., 2019-12-04) Adeyanju, O.A; Ogundare, G.
    The presence of water in crude oil emulsions presents some challenges during crude oil recovery and processing. Several methods are being used in the petroleum industry to break the stable emulsions into separate phases. This research is aimed at using centrifugation as a comparative means of breaking emulsions. Two synthetic water in oil emulsions with water: oil ratios of 50:50 and 30:70 respectively were used in the study. The 50:50 water- oil emulsion attained the water separation efficiency of about 61% which was higher than water separation efficiency of 57% returned by the 30:70 water-oil emulsion. The relative stability of the 30:70 was due to its relative lower volume of dispersed water in the continuous oil phase. The study shows that increase in the time of centrifugation (i.e., circulation period) agitates the emulsion more and hence more percentage of water droplets coming closer thereby increasing their rate of flocculation, coalescence and settling.
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    Open Access
    Experimental Investigation of the Effects of Different Environmental Conditions on Pipelines Corrosion Rates
    (Society of Petroleum Engineers, 2019-08-03) Adeyanju, O.; Oyekunle, L.
    An estimate of about $18.5 million are expended by industries in Nigeria yearly on corrosion, the oil and gas industry takes more than 65% of this cost due to the peculiar nature of their facilities and operational conditions. In spite of the use of galvanized pipeline and application of the anti-corrosion coating of crude oil pipeline and other metallic structure in the oil and gas industry, corrosion failures are still daily occurrences. These corrosive failures have been attributed to the environmental conditions in which the pipeline and other metallic structures are located. This research studies the rate of deterioration (corrosion rate) of carbon steel pipeline (flow pipe) under five different environmental conditions, coated with different anti-corroding agents, and subjected to different temperatures and pH values. Five Different environmental conditions through which pipelines are laid (Top soil + Fresh water, Sea water bed sand + Sea water, Lagoon water, Seawater, NaCl solution (0.5M)) were simulated in the laboratory. Different seventy gram (70g) samples of the carbon steel pipeline were used as the coupon samples. Red oxide oil paint and tar paint were used as the anti-corroding agents. Water bath was used in regulating the temperature and different concentration of HCL and NaOH were used to vary the pH. Weight loss method was used to calculate the corrosion rates. Results show that carbon steel resists corrosion better when buried in soil than when submerged in water; also the corrosion rate is more in sea water than in the lagoon water of relatively smaller salinity. The rate of corrosion was observed to increase with: increase in temperature, increase in salinity, and increases in acidity and alkalinity. Also the tar paint is more effective as anti-corrodant than the red oxide oil paint when applied to the carbon steel pipeline under same environment conditions. The study successively reduced the corrosion rate of the 70g coupon sample from 0.00127g/day when the sample were suspended in 0.5M, NaCl solution to 0.000104g/day when pipeline coated with tar paint are buried in dry soil.
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    Open Access
    Experimental Studies of Sand Production from Unconsolidated Sandstone Petroleum Reservoirs in Niger-Delta
    (Faculty of Engineering, University of Nigeria, Nsukka, 2011-06) Adeyanju, O.; Olafuyi, O.
    Production of sand during oil and gas exploration causes severe operational problem for oil and gas explorers especially companies producing from unconsolidated formations. Most reservoirs in the Niger-Delta fall in this category. Production oil and gas from such reservoirs has been limited by rate-dependent sand production and fines migration which resulted in near wellbore formation plugging. To prevent this occurrence, controlling the oil and gas flow rate will be of high importance to the oil and gas companies especially the producers operating in the Niger Delta. A physical model which has capacity for both consolidated and unconsolidated samples has been used to simulate the effect of flow rates, confining pressure, pressure drawdown and fluid viscosity on sand production in the Niger Delta. The model was also used to determine the ability of using the flow rate to control the production of sand. Sand sample from an unconsolidated reservoir in the Niger Delta was used in the model. Light and heavy crude oil with laboratory simulated brine was used as fluids as well. Results from the studies showed that the sand production increased as the following parameters; the flow rates, the confining pressure, the drawdown and the viscosity of the formation fluid are increased. The results also indicates that high sand-free flow rates can be achieved if the sand formation is mechanically confined (compacted). Further investigation revealed that sand production can be controlled by managing the flow rate alone when light oil was used while it is impossible to control sand production by managing the flow rate alone when heavy oil was used.