Study On The Numerical Simulation Of Paraffin Deposition And Clear

The paraffin deposition in oil and gas system has been a the serious problem in the petroleum industry. The paraffin deposition would appear in all the producing and processing system, such as a reservoir, wellbore or surface lines. In recent years, along with the development deeply and broadly in the petroleum developing and processing, the research and resolution of the paraffin deposition is becoming the more urgent and outstanding.The purpose of this thesis is to establish a model of the paraffin deposits and removal in the reservoir and wellbore using the methods and thoughts of reservoir simulation, and to develop a numerical simulator to model the paraffin deposits and removal. It would be used to research the characteristic of the paraffin deposition in the producing process and the proceeds of the thermodynamic energy removing the paraffin, and to evaluate the influence of the paraffin deposits and the results of the removing the paraffin. At local, this is a first simulator in this research region, therefore it will be a bigger research difficulty with the heavy workload.On the basis of the study results in the past, a series research has been made in this thesis, in which developing the paraffin deposition mechanism in the reservoir and wellbore, the paraffin solubility model, the mathematical model of the reservoir percolation and the perpendicular-pipe flow include the solid phase paraffin, numerical model and numerical solution method etc, and establishing the mathematical model of the reservoir filtration and the perpendicular-pipe flow of three-phase (vapor, liquid, solid), three-component (oil , gas , paraffin ),and developing applied simulation software. Therefore a set of modeling the paraffin deposition and removal theories and methods have been formed. It is significant to research the characteristic of the paraffin deposit in the oil reservoir and wellbore, to design the referent project of the paraffin removal and to evaluate the results, and instructively significant to develop of the other solid phase deposition in oil and gas system.The developed paraffin simulator is composed of the reservoir / underburden simulator, the overburden simulator and the wellbore simulator. The reservoir simulator accurately is used to describe the flowing process of crude oil containing the paraffin and the paraffin deposit in the oil reservoir. The overburden simulator model the heat exchange of the overburden, the reservoirand the well-bore. The wellbore simulator describes the flowing process of crude oil containing the paraffin, and the paraffin deposit in the wellbore. Three sequential simulator are linked by the method of domain decomposition and various different boundaries. An integrated paraffin simulator composed of reservoir and wellbore has been made, which can used to model the paraffin deposit and removal in the reservoir and wellbore.To document the results obtained from this paraffin simulator, seven cases have been calculated by the developed paraffin simulator, including the paraffin deposit and removal in the saturated reservoir and undersaturated reservoir, the paraffin deposition in the well-bore and 3 kinds of paraffin removal.Conclusion made by developing the simulator: (l)This paper establish a new, gas, liquid and solid three-phase the filtration and the perpendicular-pipe flow mathematical model, in which the paraffin solid phase is introduced into gas and liquid two-phase filtration and perpendicular-pipe flow by paraffin the solubility model and deposit model; (2) To model the thermal removal of paraffin in fully implicit paraffin black oil reservoir simulator, the variable cloud point problem must be considered; (3) The principal of domain decomposition can be effectively used to link a wellbore simulator to reservoir and overburden simulator; (4)Two dimension heat flow must be considered in the overburden when the wellbore temperatures deviate far from the geothermal gradient;(5)The deposition model required a large deposition coefficient to get a reasonab...