Department of Chemical & Petroleum Engineering

Permanent URI for this community

https://ir.unilag.edu.ng/handle/123456789/3480

Browse

Browsing Department of Chemical & Petroleum Engineering by Author "Adeyanju, Olusiji"

Now showing 1 - 12 of 12
  • Item
    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.
  • Item
    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
  • Item
    Open Access
    An Experimental study of Rheological Properties of Nigeria Waxy Crude Oil
    (Taylor & Francis Production, 2012-08) Adeyanju, Olusiji; Oyekunle, Layioye
    Nigerian crude oils are known for their good quality (low sulfur, high American Petroleum Institute gravity). However, similar to any other paraffinic-based crudes, most Nigerian crudes contain moderate to high contents of paraffinic waxes. These waxy crudes exhibit non-Newtonian flow behavior at temperatures below the cloud point because of wax crystallization. In order to accurately predict flowing and static temperature profiles, design waxy crude oil pipelines, evaluate flow interruption scenarios, and start up requirements in the handling of waxy crude oils, the effect of temperature and shear rate on the rheology of crude oils must be determined. This work presented some experimental results on the rheology of two waxy crude oils produced from different Nigerian oil fields. A Brookfield DV-III ultraprogrammable rheometer (Brookfield Engineering Laboratories, Middleboro, MA) was utilized. The temperature dependence of rheological properties and thixotropy of these crudes were investigated. The influence of some petroleum-based diluents to depress the wax appearance temperature (WAT), their effect on the thixotropic/yield pseudoplastic behavior of two Nigerian crudes were studied and it was observed that lower wax content crude has higher tendency to regain its cohesive lattice bonding (yield strength) when left undisturbed for some days at its gel point after agitation. The experimental results showed that the addition of petroleum-based diluents to the lower wax content crude oil leads to its lost some of its yield strength regaining capacity.
  • Item
    Open Access
    Experimental study of water-in-oil emulsion flow on wax deposition in subsea pipelines
    (Elsevier, 2019) Adeyanju, Olusiji; Oyekunle, Layioye
    Experiments were performed to simulate the deposition of wax in the flow of crude oil emulsions in subsea pipeline using a validated flow facility. Two crude samples and their respective formation water from two oil fields in southern Nigeria were used to synthetize two different emulsified crude oil samples (A and B). The trapping of the water globules in the wax deposits dominates the wax deposition rate initially but later the shear removal and the molecular diffusion dominate leading to decrease in the wax deposition rate. As the water (BS& W) composition in the emulsion increases from 10 to 40%, the pour point temperature (PPT) increases from 30 to 41 °C, and the viscosity increases from 40 mPas to 142 mPa at a crude oil temperature of 26 °C. The addition of 45 ppm of long chain acrylate ester co-polymer as pour point depressant depressed the dimensionless wax thickness by 37.5% and 34.3% for the blank emulsified crude oil A and B respectively. The effect of the commercial demulsifier to reduce the wax deposition rate was more successful in crude oil A reducing the wax dimensionless thickness by 58.9% and 43.0% when mixture of 25 ppm of the demulsifier and 45 ppm of long chain acrylate ester co-polymer were added to blank emulsified crude oil A and B respectively. The used demulsifier is more effective in crude oil A compared to crude oil B. Efforts should be made to study the effectiveness of different demulsifiers on each emulsified crude oil before their application for water separation.
  • Item
    Open Access
    A New Model for the Prediction of Real Time Critical Drawdown Sand Failure in Petroleum Reservoirs
    (Taylor & Francis Production, 2014-07) Adeyanju, Olusiji; Oyekunle, Layioye
    Petroleum producers are now realizing the risk of failure in petroleum reservoirs and consequently sand production is now a dreaded process in the industry. As a result, failure analysis of reservoirs rocks for sanding potential prediction purposes has become a routine activity more than ever before. Due to the high cost and operational and safety implications of the risk of sand failure, the efficient management of these risks for field operation optimization requires a reliable failure model. Most of the existing models failed to capture the real time failure of the reservoir’s sand, and those that tried to capture the real time failure criterion required parameters that are difficult to acquire. The developed model modified the Griffitti rock failure criterion using McClintock and Walsh hypotheses to predict the current critical drawdown pressure of petroleum reservoir. The required parameters for the application of the developed model can be easily determined. The error analysis from the model in relation to the field data when compared with those of Oluyemi and Oyeneyin’s model showed that the developed model gives better predicting ability
  • Item
    Open Access
    A New Model for the Prediction of Real Time Critical Drawdown Sand Failure in Petroleum Reservoirs
    (Taylor & Francis Production, 2014-07) Adeyanju, Olusiji; Oyekunle, Layioye
    Petroleum producers are now realizing the risk of failure in petroleum reservoirs and consequently sand production is now a dreaded process in the industry. As a result, failure analysis of reservoirs rocks for sanding potential prediction purposes has become a routine activity more than ever before. Due to the high cost and operational and safety implications of the risk of sand failure, the efficient management of these risks for field operation optimization requires a reliable failure model. Most of the existing models failed to capture the real time failure of the reservoir’s sand, and those that tried to capture the real time failure criterion required parameters that are difficult to acquire. The developed model modified the Griffitti rock failure criterion using McClintock and Walsh hypotheses to predict the current critical drawdown pressure of petroleum reservoir. The required parameters for the application of the developed model can be easily determined. The error analysis from the model in relation to the field data when compared with those of Oluyemi and Oyeneyin’s model showed that the developed model gives better predicting ability
  • Item
    Open Access
    A New Unified Model for Predicting non-Newtonian Viscosity of Waxy Crudes
    (Taylor & Francis Production, 2012-04) Adeyanju, Olusiji; Oyekunle, Layioye
    Viscosity determination in the non-Newtonian regime has always been a major problem in the oil industry. This is due to its dependence on the wax precipitated shear and thermal history of the crude oil. The present shear rate dependent viscosity model was developed by applying the theory of suspension rheology. This model is characterized by its capacity to predict viscosities of crude oils with different shear and thermal history and those containing petroleum-based diluents. Once viscosities at two temperatures above the wax appearance temperature (WAT) and apparent viscosity in the non Newtonian regime are known, viscosities or apparent viscosities at any temperature above the gel point can be determined by using the model together with the concentration of precipitated wax at the specified temperature. Verification of the model by using two Nigerian crudes with different shear and thermal histories and two crudes obtained from the literature shows that the model predicts viscosities with an average absolute deviation of 4.9%.
  • Item
    Open Access
    A New Unified Model for Predicting non-Newtonian Viscosity of Waxy Crudes
    (Taylor & Francis Production, 2012-04) Adeyanju, Olusiji; Oyekunle, Layioye
    Viscosity determination in the non-Newtonian regime has always been a major problem in the oil industry. This is due to its dependence on the wax precipitated shear and thermal history of the crude oil. The present shear rate dependent viscosity model was developed by applying the theory of suspension rheology. This model is characterized by its capacity to predict viscosities of crude oils with different shear and thermal history and those containing petroleum-based diluents. Once viscosities at two temperatures above the wax appearance temperature (WAT) and apparent viscosity in the non Newtonian regime are known, viscosities or apparent viscosities at any temperature above the gel point can be determined by using the model together with the concentration of precipitated wax at the specified temperature. Verification of the model by using two Nigerian crudes with different shear and thermal histories and two crudes obtained from the literature shows that the model predicts viscosities with an average absolute deviation of 4.9%.
  • Item
    Open Access
    Optimal Wax Inhibitor Formulations for Nigerian Crude Oil-Water Emulsion Flow in Subsea Pipelines
    (Nova Science Publishers, Inc., 2018) Adeyanju, Olusiji; Oyekunle, Layioye
    Nigerian crude oil and in fact most crude oil samples produced from different reservoirs around the world are characterized with high percentage of sediments and water, coupled with the presence of resin and asphaltene in the crude oil compositions which aid in the formation of water in oil emulsion. There is a high probability of emulsion formation during the flow of crude oil through the pipeline. In this study, an experimental design method was used to optimize the wax inhibitors/demulsifier mixture performance during the flow of emulsified crude oil in subsea pipeline. In the formulation of optimal wax inhibitor mixtures, addition of demulsifier (Butyl-acrylate) to each of the crude oil samples and inhibitors (mixture of acrylate ester polymers and xylene) increased the efficiency of the wax inhibitors at low cooling temperatures (4oC - 16oC). The average wax inhibition (WIav) values of 67% – 82% were obtained with a solution of the demulsifier, the inhibitors and the oil compared to values of 46% – 65% without the demulsifier. The demulsifier term and its interaction with other terms also had significant influence on the WIav, with P-values of less than 0.05 (P < 0.05) at the optimum AEP/Xylene/Butyl-acrylate formulation.
  • Item
    Open Access
    Optimum demulsifier formulations for Nigerian crude oil-water emulsions
    (Elsevier, 2019) Adeyanju, Olusiji; Oyekunle, Layioye
    The formation of crude emulsion during oil production and processing is a challenge of significant proportions to the oil producers. Studies show that about two third of Nigerian crude oil production is in form of water in oil emulsion. For economic and operational reasons, it is necessary to separate the water completely from the crude oil before transportation or refining. Efficiency of separation of crude emulsions is of major importance to producers. To this end, this study primarily seeks to investigate the formulation of effective demulsifier that can be used to achieve this aim; and in so doing, the optimal separation efficiency attainable by this demulsification process is determined. Six different samples of water and oil soluble demulsifiers were used on two different samples of synthetic emulsion (sample I and II (both water in oil emulsion) from different Nigerian oil fields). The bottle test method was used to determine the percentage water separation for each crude oil emulsion/ chemicals (demulsifiers) mixture. The concentrations of the combined six chemicals (demulsifier samples A–F) in the mixture were related to the percentage water separation using response surface methodology central composite design (RSMCCD). Results show that the optimum concentrations of demulsifiers A–F are 59 ppm/39 ppm/29 ppm/20 ppm/29 ppm/13 ppm respectively for crude oil sample I. While 54 ppm/40 ppm/25 ppm/21 ppm/29 ppm/8 ppm respectively were observed as optimum concentration for crude oil II. The combination of these chemical was observed to return better performance than the existing commercial demulsifiers with percentage water separation of 92% and 94% compared to percentage water separation of 87% and 90% returned by one of the currently available demulsifier used in the petroleum industry for crude oil A and B respectively. Hence, the need to carry out optimization analyses on different emulsified crude oil cannot be over-emphasize.
  • Item
    Open Access
    Prediction of Volumetric Sand Production and Stability of Well-Bore in a Niger-Delta Formation
    (Society of Petroleum Engineers, 2010-08-04) Adeyanju, Olusiji; Oyekunle, Layioye
    Nigeria's Niger-Delta province has been identified as one petroleum system- The tertiary Niger-Delta (Akata- Agbada) petroleum system. Almost all the petroleum resources currently are produced from the sandstone species within the Agbada formation. Also turbidite sand in the upper Akata formation is a potential target in deepwater offshore and currently producing interval onshore. This paper presents a mathematical model to simulate sand production from petroleum reservoir subject to an open-hole completion. A coupled reservoir-geomechanical model was used to predict the volumetric sand production and associated wellbore stability. The model is based on mixture theory with erosion. The Representative Elementary Volume (REV) composes of five phases - solid matrix, fluidized solids, oil, water, and gas phase was chosen. The model also incorporates the reservoir drawdown pressure, rock failure criteria, rock types and field condition. Analytical solution of sand displacement processes is also highlighted. Results show that the magnitude of sand production is strongly affected by the flow rate, the confining pressure, the pressure drawdown and the fluid viscosity. The determined ratio of the productivity index to the saturation of the fluidized solid can be correlated to determine reservoir formation type during sand production, and predicting the wellbore stability. The model has a higher degree of validity for light and medium crude oil flow which possesses moderate lubricating properties, and therefore erosion of sand particles during production highly depends on flow rate.
  • Item
    Open Access
    Thermodynamic Prediction of Paraffin wax precipitation in Crude oil Pipelines” Petroleum Science and Technology
    (Taylor & Francis Production, 2011-07) Adeyanju, Olusiji; Oyekunle, Layioye
    Crude oils are generally very complex chemical systems consisting predominantly of hundreds to thousands of hydrocarbon compounds from simple lowmolecular-weight paraffins to high-molecular-weight waxes. At low temperatures these paraffins precipitate as a wax phase, which may cause the plugging of pipes and many other problems. In this study the cloud point and the amount of the precipitated wax at different temperatures were determined using a modified multi-solid wax model at stock tank conditions and at high pressure for three live crudes and synthetic oil. The model is based on the description of the nonideality of the phases in equilibrium using the Peng-Robinson cubic equation of state for the liquid phase with a modified afunction and the universal quasi chemical (UNIQUAC) equation for the solid phase, which takes into account the effects of temperature, pressure, and composition on the wax precipitation. The model assumes the crystalline nature of wax formed. The experimental data and model predictions reveal that the cloud point decreases with increased pressure and increases when the crude oil is mixed with more light hydrocarbons. The values predicted by the new model show very little deviation from experimental data.