- ItemRestrictedExperimental 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.
- ItemOpen AccessExperimental Study of Wax Deposition in a Single Phase Sub-Cooled Pipelines(Nova Science Publishers, Inc., 2013-08) Adeyanju, O.; Oyekunle, L.The ability to determine the severity of wax deposition is an extremely important issue, particularly in the design and development of deepwater oilfields. Though much progress has been made in the last decades to better the understanding of this complex process, yet the ability to accurately account for all the factors that affect wax deposition are currently not in existence in the wax simulators used presently in the industries. In this study an experimental methodology constructed to simulate wax deposition process was employed to investigate the influence factors controlling paraffin wax deposition to the pipe wall surface (namely, inlet oil temperature, inlet coolant temperature, oil flow rate and the wax content). Series of tests were designed to determine the effects of these influence factors on the wax content in the deposit. The experimental results revealed that the amount of wax deposited initially increases with time, attained a maximum value and gradually erode off. Also it was discovered that the wax deposition decreases with flow rates and also with the temperature difference between the flowing oil and the pipe wall, when the oil temperature is above its Wax Appearance Temperature (WAT), while the reverse is the case when the oil temperature is below its WAT. The study also established that shear dispersion, defined as the movement of wax crystals towards the pipe wall as a result of the velocity variation along the radial direction during oil flow in the pipe ignored in most of the existing models used in the existing wax deposition commercial codes was found not to be inconsequential. The flow rate rather than the flow regime was also discovered to responsible for the shear stripping of wax deposit at the wall. This experimental observation will provide a reference point and an insight for further study on wax deposition in actual pipelines. This is particularly so for oil characterized by high wax content and high gel point temperature like those produced from most fields in Nigeria’s Niger Delta.
- ItemOpen AccessOptimization of Chemical Demulsifications of Water in Crude Oil Emulsions(Elsevier, 2019-10) Adeyanju, O.; Oyekunle, L.The instability of the water in crude oil emulsion and separation of the dispersed water as free water are influenced by the emulsion properties and the operating parameters during the demulsification process. This study aims to relate these properties/operating parameters to the amount of separated water. Steps were taken to determine and validate the optimal separations that can be achieved. Six operating parameters were identified through sensitivity analyses to have an energetic effect on percentage water separation. The bottle test method was used on two different samples of water in oil synthetic emulsions (sample A and B from different Nigerian oil fields). Response surface methodology central composite design (RSMCCD) was used to design the experiment, and generate the desired regression equations/ models. Results show that optimum percentage water separations of 93 and 95% (V/V) were achieved with the emulsions A and B respectively using the combination of the optimal variables derived from the model equations. These were improvements from percentage water separations of 80 and 83% (V/V) achieved using the two crude oil samples in their naturally occurring state when the properties of the emulsions were not enhanced to their determined optimal operating conditions.
- ItemOpen AccessThe 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, OlalekanA 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.
- ItemOpen AccessModeling and Simulation of Wax Deposition in Oil Pipeline System(Nova Science Publishers, Inc., 2014-08) Adeyanju, O.A.; Oyekunle, L.O.The major challenge accompanies the transportation of waxy crude oil is the wax deposition in the pipeline. Oil Company spends millions of dollars yearly to remediate this anomaly. This necessitated the demand for an accurate mathematical model that would include all salient features of wax transportation and deposition for an ideal design of oil production facilities. A comprehensive mathematical model for the prediction of single-phase wax deposition applicable to both laminar and turbulent flow regimes is presented. The model couples energy, momentum and thermodynamic equations to deposition and removal kinetics models. Molecular diffusion, shear dispersion and the sloughing effect due to shear removal effect of flowing oil in the pipe channel have been considered. The laboratory data and field operating conditions were input to the wax deposition model, the modeling results were validated with experimental data. Results indicate that the sloughing effect ignored in most of the existing models can be substantial in both the laminar and turbulent flow regimes which characterize the field flow situation at different production periods. Overall predictive ability of the proposed model is excellent in both flow regimes judging by the Average Absolute Deviation (AAD) values of 0.0000921 and 0.0000996 by the proposed model as against AAD values of 0.0000982 and 0.000236 returned by the Hernandez et al. model in the laminar and turbulent flow regime respectively. The improvement was due to among others the ability of the proposed model to model the effect of shear removal in the wax deposition model which the Hernandez model failed to take into consideration.