Optimization Of Natural Gas Pipeline Path And Network Layout Under Topographic Relief Conditions

As one of the most important clean energy sources in current human society,the consumption of natural gas is increasing rapidly.The development of gas field and the construction of surface engineering continue to develop rapidly.As the core of surface engineering,the gathering network system is a great investment.Sichuan basin has abundant natural gas reserves,and its unique rugged area can not be neglected in pipeline network design.Aiming at the drawbacks of traditional 2-D artificial design and classification optimization,a series of researches have been carried out:The method of establishing Digital Elevation Model is studied.DEM is selected as the main medium for the expression of terrain information.By acquiring aerial images,combined with Global Mapper,the discrete 3-D terrain data can be obtained through software processing and extraction.DEM based on Grid is built via dimensionality reduction.And the approximate calculation model of pipeline three-dimensional length based on the Lagrange interpolation algorithm is set up.Path optimization of natural gas pipeline based on GIS is studied.Based on the DEM,the pipeline path optimization model is established with the minimum length of natural gas pipeline as the evaluation index,and the radius of curvature of the elastic pipeline as the constraint condition.By comparing the algorithm search efficiency under different paths,A*algorithm with Manhattan distance is used to solve the optimal path between two points.Aiming at the limitation of traditional A*algorithm,such as limited motion angel,frequent turning points,lack of smoothness and long search time,A*algorithm is improved by neighborhood extension,bi-directional search and alternative search.The example shows that,in the aspect of planning path effect,the improved A*algorithm is better to reduce the total length of the pipeline and the degree of fluctuation of the path effectively,in the aspect of searching efficiency,the improved A*algorithm greatly expands the search ability and improves the efficiency of search while greatly reducing the number of node and the computation time.Layout optimization strategy of natural gas pipeline network under undulate topography is studied.The four sub problems of well group division,optimization of gas gathering station location,optimization of pipe network connection,optimization of structure parameters of pipe network are integrated and path optimization is introduced for pipeline with large undulating degree.Four new parts are formed:global optimization of well group division and gathering station location,optimization of network connection,path optimization and optimization of technical parameters of pipe network.Layout optimization of natural gas pipeline network under undulate topography is studied.For the global optimization of well group division and gathering station location,the global optimization model is established with the minimum cost of pipeline and station as the evaluation index,and membership relations,set radius,minimum number of wells,minimum handling capacity as the constraint condition.The GA is used to solve the problem,and according to the actual situation,the traditional GA is improved:the two-layer real number is used to encode,and the elite individual reservation strategy is introduced.The alternating of dominant cross and free cross,the alternating of strong variation and intense variation and the adaptive cross&mutation probability regulation mechanism are carried out.The results show that the improved GA can be applied to the global optimization,after the 100th generation,the results tend to be stable and have good convergence.For the optimization of network connection,the initial connection mechanism of the network is introduced,and the unreasonable pipe connection is eliminated by the defined rectangle range.The Kruskal algorithm is used to optimize the network connection.After determining the network connection,path optimization of 17 gas gathering pipelines and 3 gathering pipelines with the maximum path of the slope exceeding 30 degrees based on the improved A*algorithm is carried out,the results show that the optimization effect is obvious and the maximum slope of the optimized path can be effectively controlled within 30 degrees.At the same time,the length of pipe is shorten and the maximum elevation is reduced about 10%.Finally,according to the diameter range determined by the economic flow velocity,the optimal structure parameters of the pipe network can be obtained by calculating the combination scheme of different diameter and wall thickness based on cyclic iteration algorithm.