Feasibility of pigging operations in submarine adjustable pipelines in Caofeidian Oilfield

To perform pigging operations in three submarine adjustable mixed transportation pipelines in the Caofeidian Oilfield, feasibility studies have been performed in the pipeline from WHPE to WHPD. With outstanding sealing performances, flexibility, abrasion resistance, high accessibility and capability for movements in both directions, the butterfly sealing plates in newly developed butterfly straight pig may be used in pigging operations of submarine adjustable pipelines.Through simulation of pigging processes, it is found that to perform pigging operations in submarine adjustable pipelines in the Caofeidian Oilfield is possible. Satisfactory pigging operations with average speed of 0.8 m/s and duration of 5 990 s can be implemented by using the butterfly straight pig. The maximum inlet pressure of the submarine pipeline during pigging is 2.64 MPa, significantly lower than the designed inlet design pressure of the submarine pipeline and working pressure of the pig. In addition, main risks have been identified for pigging operations in submarine adjustable pipeline from WHPE to WHPD. At the same time, relevant countermeasures have been proposed. In this way, risks in pigging operations can be controlled properly to achieve desirable operation safety performances. The reasearch results can provide guidance for integrity management and risk identification of submarine adjustable pipelines.