The Optimization Design Research On Oilfield Tree Type Water Injection Pipeline Network Based On Bi-level Programming Theory

Oilfield water injection pipeline network system is a large multiple fluid network system which includes many complex problems such as linear parametric, non-linear parametric, multiple constraints and multi-objective optimizations, whose optimization progress involoves discrete, continuous and discriminant variables, and the other multiple parameters. In the optimization progress, each component part of the water injection pipeline network are the elements that constituted by water injection stations, water distribution stations, water injection wells and the water injection pipelines, which undertake the water transport effect for connecting all stations. Therefore, this paper will take data information of each component as the micro elements and obtain the macro indicators that could directly measure the performance of network by optimization analysis.As study object, the tree type water injection pipeline network, who could be appropriately remoulded with the increasing number of water injection wells, is more flexible than the star network, while it has the advantages of less investment and easy to control in comparison to the loop network. The main energy consumption sources to the network can be divided into two aspects: one is the construction cost of network itself, the other is the operation cost. The oilfield water injection pipeline network optimization belongs to NP-hard problem, which made the researchers concentrate on single objective and unrelated multi-objective optimization problem that couldn’t ensure the optimal overall situation of network. This paper focuses on optimizing the overall situation of oilfield water injection pipeline network and carries on the study of the following parts:(1) Quoting the bi-level programming theory as theoretical basis for the network modeling in which trying to optimize construction investment and operation cost of network, the study link context layer model by using pipeline diameter as decision variables to make the construction cost and operation cost of whole network optimal.(2) In the process of network topology optimization, quoting the concept of water injection trunk pipeline, which namely the water injection pipeline in the same layer station of tree type water injection pipeline network. The main content of network topology optimization included the partition to the water injection well, the position of water distribution station and water injection station and the selection of ramose water injection main stem. Based on the criterion of calculating distance function, the optimization algorithm that the selection process to the position of station used was electromagnetism-like mechanism algorithm, who had the advantage of high efficiency and few parameters, by which the study improved the speed and accuracy of the optimization.(3) In the process of network operation optimization, this paper use the law of conservation of mass and energy as the standard to analyzing the main sources of energy consumption in the operation process of pipeline network and making the water injection pipeline diameter combination scheme of the whole water injection pipeline for calculating the cost of pipeline network energy.On the basis of above work, this paper implement the establishment, settlement and program output for the bi-level programming model by programming procedure under the environment of MATLAB on computer.