Mill Creek Gas Field Gas Pipeline Internal Corrosion Prediction Method Study

With the continuous growth of the running time of the sour gas fields, the internal corrosion of gathering pipeline has become an urgent problem in the process of pipeline operation. Compared with the long-distance pipeline, the diameter of the gathering pipeline is smaller, the elevation has more ups and downs, the number of elbows is many more,and the radius of curvation is rather smaller, so it is very difficult to adopt internal detective means to do comprehensive examine for the pipeline. And it has a certain theoretical significance and application value that establishing internal corrosion prediction mechod of gathering pipelines in MOXI gas field, based on the specific circumstances of gathering pipelines in MOXI gas field.The mainly work of the paper is the following aspects:(1) The research situation of pipeline internal corrosion prediction at home and abroad is investigated, and the methods and evolutions of pipeline internal corrosion prediction are analyzed. Both provide a theoretical basis for the paper.(2) The basic informations of seven gathering pipelines in MOXI gas field are collected, and the corrosion rule of the pipelines is analyzed. And the main factors affecting internal corrosion in the pipelines are summarized, based on the analysis.(3) The WG-ICDA is elaborated,and the semi-emprical formula De Waard95and Top-of-Line in WG-ICDA is applied to predict internal corrosion rates of the pipelines in MOXI gas field.Then some field excavation datas of the pipelines are utilized to verify the validity of the approaches.(4) Multiphase flow software is applied to calculate twenty one corrosive impact parameters of the pipelines. And Gray relational analysis is applied to do weight analysis of the calculated parameters, with the field excavation datas. Seven parameters, HOL, HTK, PSID, USL, TAUWHL, ANGLE, TAUWG, are calculated as the relatively larger weight parameters affecting internal corrosion of the pipelines in MOXI gas field.(5) Then the relatively larger weight parameters are chosen to do neural network prediction. And after a comparation of different prediction results calculated by BP, GA&BP,PSO&BP methods, the GA&BP method is selected as the internal corrosion prediction method of gathering pipelines in MOXI gas field.(6) Fifty four field excavation datas of one gathering pipeline in MOXI gas field is utilized to determine the applicability of the selected prediction method.