Injection System Simulation Research Articles

Optimization of Pipe Network Simulation Algorithm for Tree-Shaped Water Injection System in Large-Scale Oilfield

As intelligence technology develops, there is a higher requirement for computing speed and accuracy of water injection system simulation. In this paper, aiming at the tree-shaped water injection pipe network system of large-scale oilfields, based on the energy equation for calculating the pressure drop [Formula: see text] of pipe section, a mathematical model of the pipeline unit and the node unit is established, and finally, a mathematical model of pipe network for the entire water injection system is established; then, the improved iterative algorithm is used to solve the simulation model of water injection system. In this way, we determine the boundary calculation conditions, take the water injection station as reference node, and use the maximum pressure of water injection well as the initial value of the reference node for calculation, which reduces the number of iterations in model calculation; by comparing the simulation results of different iteration steps, 0.01 is selected as the iteration step size due to its higher calculation accuracy; and the calculation process has also been optimized. The process of solving the characteristic matrix [Formula: see text] is combined with the process of calculating the pressure drop [Formula: see text] of pipe section, and placed outside the algorithm loop, thereby shortening the calculation time of a single cycle and reducing the calculation amount of the algorithm. The application cases show that the proposed optimization algorithm for water injection system pipe network simulation can be used as an effective method to improve the solution speed and calculation accuracy of the simulation algorithm of tree-shaped water injection system in large-scale oilfields.

Construction of a digital intelligent evaluation platform for energy consumption of large oilfield water injection systems

With the development of oilfield water injection systems becoming more and more complex, relying on artificial experience to judge the efficiency of energy consumption and the status of the system more difficult. Based on hydraulic theory and matrix theory, establish the characteristic equations of the node unit, pipeline unit and auxiliary unit of the water injection system, and use the flow balance to form the overall matrix equation of the water injection system. Established a theoretical model of water injection system simulation, based on this, build a digital intelligent evaluation platform for water injection system energy consumption. In this way, it simulates the production operation status of the water injection system under theoretical conditions and compares it with the actual production operation data, so as to accurately analyze and evaluate the current status of the water injection system’s pipe network energy consumption and the operating efficiency of the branch pipe network energy consumption of each water injection station. The intelligent analysis and evaluation of energy consumption of the water injection pipe network system has been realized, and the optimization and transformation goals have been defined. It has played a significant role in promoting the realization of digital and intelligent oilfield water injection systems.

Fuel Common Rail Injection System of RT-Flex Marine Intelligent Diesel Engine and its Simulation Dynamic Model

Based on comprehensively analyzing the whole structure and its working performance of RT-Flex marine intelligence diesel engine and entirely mastering this kind of engine fuel common rail injection system’s composition, working principle, taking 7RT-Flex60C as simulation object, the mathematical models of this system’s composing part are designed, by using Matlab/Simulink simulation tool, fuel common rail injection system simulation model is set up, then comparing with the simulation data with rack test data, the accuracy and effectiveness of the model are test and verified. The built up model provides a convenient and practical method for design, optimizing and simulation of fuel common rail injection system.

A Comprehensive Thermodynamic Approach to Acoustic Cavitation Simulation in High-Pressure Injection Systems by a Conservative Homogeneous Two-Phase Barotropic Flow Model

A general conservative numerical model for the simulation of transmission-line unsteady fluid dynamics has been developed and applied to high-pressure injection systems. A comprehensive thermodynamic approach for modeling acoustic cavitation, i.e., cavitation induced by wave propagation, was proposed on the basis of a conservative homogeneous two-phase barotropic flow model of a pure liquid, its vapor, and a gas, both dissolved and undissolved. A physically consistent sound speed equation was set in a closed analytical form of wide application. For the pure-liquid flow simulation outside the cavitation regions, or in the absence of these, temperature variations due to compressibility effects were taken into account, for the first time in injection system simulation, through a thermodynamic relation derived from the energy equation. Nevertheless, in the cavitating regions, an isothermal flow was retained consistently with negligible macroscopic thermal effects due to vaporization or condensation, because of the tiny amounts of liquid involved. A novel implicit, conservative, one-step, symmetrical, and trapezoidal scheme of second-order accuracy was employed to solve the partial differential equations governing the pipe flow. It can also be enhanced at a high-resolution level. The numerical model was applied to wave propagation and cavitation simulation in a high-pressure injection system of the pump-line-nozzle type for light and medium duty vehicles. The system was relevant to model assessment because, at part loads, it presented cavitating flow conditions that can be considered as severe, at least for a diesel injection system. The predicted time histories of pressure at two pipe locations and of injector needle lift were compared to experimental results, substantiating the validity and robustness of the developed conservative model in simulating acoustic cavitation inception and desinence with great accuracy degree. Cavitation transients and the flow discontinuities induced by them were numerically predicted and analyzed.

Development of cavitation and enhanced injector models for diesel fuel injection system simulation

To expedite the application of fuel injection equipment to diesel engines, powertrain engineers are simulating the rate of injection with computer models. Many of the simple models give quite substantial errors if fuel cavitation in the high pressure system and the variations in bulk modulus with temperature and pressure are not included. This paper discuses cavitation and a companion paper discusses the treatment of non-linear bulk modulus. Diesel fuel injection nozzle hole size has been reduced and the injection pressures have been raised, to improve combustion, and the termination of the injection has been accelerated, to reduce carbon particle mass in the exhaust. High injection pressures and rapid termination set up very large hydraulic waves in the pipes and drillings of the fuel injection system, be it pump-pipe-nozzle or accumulator/common rail in type. The fuel momentum generated in these vigorous wave actions leaves such low pressures in parts of the system that vapour bubbles form in the fuel. Cavitation changes the bulk modulus of the fuel and the collapse of the cavities imparts sudden high pressure pulses to the fuel columns in the system and changes injection characteristics significantly. When modelling devices to control injection rate, the cavitation and non-linear bulk modulus have to be incorporated into the model. To this end, the concept of ‘condensation’ has been useful. The cavitated pipe section is divided into liquid and liquid + vapour mixture columns and modified momentum and mass conservation equations are applied separately. The model has been validated with a particular application of a rotary distributor pump to a high speed direct injection diesel engine, which is one of the more difficult fuel injection systems to model in which cavitation occurs at several operating conditions. The simulation results show the cavitation characteristics very well. This cavitated flow calculation model may be applied to other one-dimensional flow systems In addition, a more comprehensive injector model is introduced, which considers two loss factors at the needle seat and holes, sac volume, and viscous drag and leakage. This enhanced injector model shows some improvement at low load conditions