The Effect of Viscosity on Tubing Performance: A Case Study of Well_XX in the Niger Delta, Nigeria

Abstract

and Mokhov, 2004). Sakharov and Mokhov (2004) in their experiment with high viscosity oil observed a new positive frictional pressure difference. Adequate knowledge of this trend of High viscosity oil will aid in getting the optimum design of wells. The proper selection, design, and installation of tubing string are critical parts of any well completion. Tubing strings must be sized correctly to enable the fluids to flow efficiently or to permit installation of effective artificial lift equipment. The optimum tubing size is selected to obtain the desired production rates at the lowest capital and operating costs. This usually means at the maximum initial flow rate and maintaining it as long as possible. Whatever the case, the selection process inevitably involves analysis of the gross fluid deliverability and flow stability under changing reservoir conditions to confirm that the production forecast can be met. Abstract: One of the parameters used to determine Reynolds numbers is viscosity and is the value of the Reynolds number that indicates if the flow is laminar, transition or turbulent flow. High viscosity oil and conventional oil require different amount of gas rate to lift them from the well heavy oil consume up to 3-5 volume above low vicious oil. Friction factor and the liquid holdup are gotten from the value of viscosity. Pressure gradient and liquid holdup depends on flow pattern so accurate prediction of flow pattern is very important. Increase in liquid viscosities result in lower intermittent region. The existing Mechanistic model were developed and validated with low viscous crude between 10cp and 110cp as such they are not able to predict pressure drop for high vicious crude of viscosity above 100cp to 500cp accurately as these model underestimate Pressure drop. The dynamics of slug flow and the film flow zone were the basis that characterizes the Hydrodynamic model developed and the film in the slug unit is used as the control volume. Duns and Ros (1964) Model was used to validate the model with Field Data. The poor prediction of pressure gradient by model is as a result of not identifying the right flow pattern as each model is flow pattern dependent. A tubing is too small causes large friction and limits It also may restrict the type and size of artificial lift equipment. A tubing string that is too large may cause heading and unstable flow, which results in loading up of the well and can complicate work-over operations. The objective of this study is to develop a viscosity model for High viscous crude in the range (100cp-500cp) in a vertical oil well as it relates to well for upward flow as it relates to well performance. To investigate effect of high viscous oil in vertical well as it affects Liquid Holdup and pressure drop. The model develop was validated with Duns and Ros Model Sensitivity analysis using different values of Superficial; liquid and gas velocities show its effects on oil well performance. At very low values of superficial liquid (0-05m/s to 0.1 m/sand gas (0.5 m/s to 2m/s), 2.067 in (50.8mm) velocities at high liquid viscosity of 500cp positive frictional pressure exist. Total pressure increases when frictional pressure increase resulting from increase in liquid holdup due to high viscosities liquid. The Model develop can be used to predict adequately liquid Holdup and Pressure drop for High Viscous crude. study the result of the heavy oil viscosity Data gotten from the oil wells in Niger Delta to compare with the results of the model develop and that obtain from Duns and Ros Model Available literature reveal that a model is yet to be develop that capture the behavior of High Vicious crude in the range ( 100cp to 500cp ) as only experimental studies that have carried as in the below.