Research And Application Of Oilfield Water Injection System Optimization

Water injection, as a significant method to increase the production in oil field development, can inhance reservior energy. With the increase of water injection development time, the oil displacement efficiency reduced, which lead to the deduce in bottom hole flow production is reduced. Water injection rate and the water injection pressure are the most important water injection parameters, which directly affect the efficiency of water injection and the effect of water injection. When the water injection rate and water injection pressure are in accordance with the optimal working conditions, the oil displacement efficiency can be improved. Water injection parameters can be obtained by water injection system, of which water injection pump is the essential component.In order to achieve the optimal injection parameters, it may be work in idle condition which cause unnecessary loss of mechanical and even shorten the service life of the water injection pump, reduce the economy of water injection pump. Therefore, aiming at solve the problem of the inconformity of injection rate and injection pressure, this paper regard high-speed operation of the injection pump as the constraint condition, proposed new speed control scheme of parallel pumps basing on the research of the character of injection pumps and pipelines, and verify the feasibility of the scheme, and analyze the schemes from economy, safety and operation respects. This paper mainly finished the following research work:(1)This paper introduced the composition and process flow of water injection system, the determination method of the working point of the water injection pump and the method to change the working point, which namely throttle adjustment and frequency adjustment. Then, with the information provided by pump factory and oil production plant, this paper got the fitting curve by improved neural network algorithm based on adaptive learning efficiency and additional momentum method. This method has the advantage in solving the following problem:the standard neural network algorithm is easy to fall into the local minimum, the network learning is slow, and the hidden layer nodes are selected according to the experience;(2)Basing on the model of water injection pump and pipeline branch, this paper then made a comparison between the method of establishing model of water injection system using shared pipeline regulation mode and non shared pipeline regulation mode. In addition, this paper established the parallel model with different method and different water injection pipeline regulation method;(3) This paper made a research of the centrifugal pump station configuration of the block, obtained the optimal water injection parameters through reservoir optimization,.analyzed the current performance status of the water injection system.In the premise of satisfying single water injection parameter, the section of the other injection parameter was determined;(4)The principle of injection pump selection and multiple injection pumps selection was introduced. The mode and operation mode were determined by the high-speed operation section of the water injection pump. With regard to the injection pump selection principle and optimization principle, the injection pump reselected and recombined. On the basis of ensuring the water injection pump is effective, more rational pump combination scheme was proposed and an performance comparison was made to assess every scheme.The results showed that the water injection system using the proposed configuration scheme can reach the optimal range of the water injection rate the injection pressure respectively, and was also operated at the optimal point. This water injection system optimization solution mainly solved two problems:first, the water injection rate and pressure of the pump station can be conform with the request of the oil field; second, the water injection pump run effectively, which improved the economy of the water injection pump and the oil displacement efficiency. Eventually, the bottom hole flow production is increased.