Pipeline Integrity Management of Unpiggable Pipelines by CorrosionModelling and Prediction Based on Topside Piping Inspection Data in theMature Field Offshore North West Java

摘要

Pertamina Hulu Energi - Offshore North West Java, also known as PHE-ONWJ, owns 426 subsea pipelinesfrom which only 185 are active operating to support PHE-ONWJ's production activity and the rest, 241pipelines, are inactive which status is either remain idle or being preserved. Need to be noted that 67% or284 pipelines aged more than 30 years, which is more than its design life. From which, 120 pipelines are stillactively operating distributing fluids such as Oil, Gas and 3-phase. Multiple events of leak have occurredwhich implicates PHE-ONWJ's production activity. Based on observation, more than 90% of leak events occurred, were caused by internal corrosion. Thespecific cause is that PHE-ONWJ pipelines transports such fluids that contains corrosive agents such highCO2 content, sands or solid particles, SRB and water. The existing integrity management plan such as in-line inspection, fluid sampling, chemical injectionand others have been performed onto several pipelines. However, since the size of PHE-ONWJ's pipelinenetwork facility is complex and massive, to perform in-line inspection to all pipelines is not economicallybeneficial. Moreover, performing in-line inspection induced high risk and not all of the pipelines arepiggable either because of its design or operating condition. Therefore, by considering such conditionsmentioned previously, an effective and efficient pipeline integrity management developed based oncorrosion rate prediction from topside piping within corrosion circuit with pipeline. It is clear unwanted event such leak shall interrupt PHE-ONWJ production activity, moreover the age ofmost pipeline facility are old which means it has probability to fail, even though not all leak event associatedwith the age of the pipeline. To maintain and predict failure event such as leak or even rupture, a corrosionmodel has been developed. This model is constructed from combining several parameters which are; fluidsampling, In-Line Inspection of several pipelines with different services, Topside piping inspection data,Operating history and pipeline design data. The model generated in the form of an equation that associatestopside piping corrosion rate and pipeline corrosion rate which both were obtained from inspection data andthe boundary is operating and design history of the pipeline itself.