Study On Tracking And Prediction Of Multiphase Flow Pipeline System

In order to cope with high risk,high technology,high cost and harsh natural environment,the upstream long-distance oil-gas multiphase pipeline system urgently needs systematic simulation,builds corresponding models and algorithms,develops the automation software and system which can serve the oil-gas production field,and supports the transformation and upgrading of oil-gas development to new production mode under the new development concept of intelligence,green and low carbon.Firstly,the general mathematical description of unit and connection relationship in long-distance multiphase flow system is abstracted by combining graph theory and topological method.Then,the split-phase multi-fluid model of the multiphase flow pipeline is constructed by deducing the flow control equation and the closed relationship,and the control equation of the plane radial flow is given for the Darcy seepage process in the reservoir.simultaneously,the closed relationship between the oil pipe in borehole and the flow in annulus is established based on the pipe flow model.Finally,considering the main control units such as pump and oil nozzle in actual production,the flow model under the unified framework is given from the point of view of force and energy,thus the mathematical description of various flow processes in actual production system is formed.Secondly,based on the calculation of fluid characteristics,flow model treatment and flow unit identification,a correlation calculation method for flow process of mixed transportation production system is proposed.First,an algorithm for fluid physical properties under component model and black oil model is given for definite and nondefinite fluid types.Then,a general partition method of system units is established by introducing subsystem identification method.On this basis,staggered grids are used to discretize the partial differential unit model.Besides the specific calculation steps of flow process within the subunit,an association algorithm between the unit systems is given.Finally,the fluid physical properties calculation software PVT and the flow process calculation software MPF of the multiphase mixing transportation system are developed,and the rationality of the calculation results is verified by simulation.Then,combining with automatic control algorithm,a dynamic flow process model is given based on the flow process in oil-gas-water three-phase separator coupled with liquid level control,flow control and pressure control,and its discrete calculation format is derived.A flow calculation method combined with control process simulation is proposed to verify the reasonableness of the algorithm by using commercial software for the crude oil primary treatment process of an offshore oil field.Finally,starting from the engineering application and actual production demand,the self-developed core software is introduced from the aspects of architecture design,software and hardware development,communication mode and application effect for the offshore oil and gas field underwater production system and platform production system,hydrate depressurization and TPO system,onshore oil and gas field well pad gathering system,etc.The software can provide on-site real-time production and flow of hydrothermal conditions,which includes many integrated simulation modules such as oil and gas well virtual metering system,wellbore flow guarantee system,subsea pipeline operation and oil,gas and water treatment process analysis module.