Operation Protection And Risk Analysis Of Shale Gas Fracturing Water Supply Pumping Station System In Changning Area

The “factory” fracturing mode of horizontal well group is adopted in Changning shale gas block,and the construction scale of shale gas fracturing is large.The construction site water supply pumping station system is mainly responsible for fracturing water supply of new wells in Changning shale gas block,production back discharge fluid and domestic water consumption of central stations and well groups.The main problems existing in the operation of the water supply system in Changning shale gas block are as follows: unreasonable pump selection leads to pump operation deviating from high efficiency area,water hammer phenomenon of pipe network caused by long-distance multi-pump parallel connection,safety hidden danger caused by long-term operation of pumping station,and so on.By using the method of combining theoretical analysis with engineering application,this paper studies the existing pipe network from the aspects of optimal selection of centrifugal pump,water hammer protection and risk analysis of pumping station operation.The optimal design method of centrifugal pump selection in pumping station is put forward,and the optimal selection software is developed.Taking the minimum operating cost of the pumping station as the goal of the optimal selection of each pump group,and taking the pump head and resistance as the constraint conditions,a more mature algorithm-integer branch demarcation algorithm is adopted to optimize the pump selection.The optimal selection software of centrifugal pump is developed with the help of MATLAB software.the software modules mainly include: pipeline characteristic curve calculation module,water demand calculation module,centrifugal pump type optimization module,pumping station operating point calculation module.Type selection through software can reduce the workload of pump selection and improve the efficiency and accuracy of pump selection.In order to solve the influence of pump stopping water hammer on pumping station in Changning water supply network,the basic equation of transient flow of water hammer is established.The pressure fluctuation and pipeline cavitation at the outlet of pumping station are quantitatively analyzed by using AFT Impulse transient hydraulic calculation software.The optimization and improvement scheme of water hammer is put forward.through the comparison of water hammer force calculation,it is concluded that adding water hammer eliminator at the outlet of pumping station and setting exhaust valve at fixed point can effectively reduce the influence of water hammer and play a positive protective role.A method of operation risk analysis of water supply pumping station based on fuzzy theory and Bayesian network is proposed.Based on the statistics of the problems and safety hidden dangers of pumping stations in Changning shale working area,the fault types are divided into station construction problems,pipeline and ancillary facilities problems and water supply facilities and equipment problems.According to its working environment,occurrence frequency and harm degree,the risk factors of pumping station engineering are analyzed by fault tree method,and the SAM method is used to aggregate the fuzzy opinions of experts to get the failure probability of basic events,so as to reduce the uncertainty of basic event probability.According to the transformation rules of fault tree logic gate,the Bayesian network of pumping station engineering risk analysis is established,the sensitivity analysis and posterior probability analysis of basic events are carried out,the weak links of fault are found and some suggestions are given.