According to the characteristics of Hangjinqi Gas Field and the problems existing in exploitation, a calculation model was established by using OLGA software,then the optimization study on gathering process was carried out. The relative errors of the results calculated using the calculation model were less than 3%, so the actual operation conditions of the pipelines could be simulated accurately. Based on the calculation model, the amount of hydrate formation on high and low wellhead pressure, gathering distance with water and without water was calculated, respectively. The results showed that:The downhole choke, no wellhead heating, no alcohol injecting low pressure gathering process with water was most suitable for Hangjinqi Gas field, and it could resolve the problems of complex geomorphological conditions effectively, such as low point effusion, hydrate plugging, poor dehydration effect when liquid production was high at the early stage of high pressure gathering process. The single well entering station gathering distance was 6.5 km((DN80), two wells were 7 km(DN80-DN100) and three wells were 4 km(DN80-DN80-DN100).

By setting up numerical models of pipeline normal operation, temperature drop along the pipeline after shutdown and restart procedure, the normal and opposite direction transportation pipeline shutdown and restart procedure were described. The relative errors of the results calculated using the numerical models were less than 2%, so thermal variation along the pipeline can be simulated accurately. Based on the numerical models, maximum safe time after shutdown in different seasons, temperature drop along the pipeline after shutdown and flow recovery after restart in winter were calculated, respectively. The results can provide evidence for production management, safe and highly efficient operation of hotoil pipeline.