The Consequences of Accidental Pipeline or Umbilical Releases During Brownfield Pipelay Operations

Abstract Compared to greenfield developments, pipeline and umbilical pipelay operations in brownfield environments are inherently more complex, requiring additional planning and consideration of hazards due to the potential risks posed to existing subsea infrastructure. The accidental release of a pipeline or umbilical during pipelay in congested subsea fields presents significant threats, such as impact damage to existing subsea equipment. Similar hazards are present when pipelay operations are conducted along installation corridors with pre-existing pipelines. Potential consequences of an accidental pipeline release during installation include subsurface containment loss, functional impairment, and reduced production. This paper introduces a technical framework designed to assess the consequences of accidental pipeline or umbilical releases during brownfield pipelay operations on existing subsea infrastructure. The approach leverages dynamic simulations to identify threatened seabed regions and calculate the kinetic energy imparted to subsea pipelines and equipment. Additionally, it describes the application of nonlinear Finite Element Analysis (FEA) to predict the extent of damage to subsea elements based on energy levels derived from dropped pipeline simulations. The framework is applicable to both J-lay and S-lay pipelay methods in deep and shallow water environments. The paper concludes with a discussion on post-processing detailed simulation results into a format that is easily interpretable by technical safety teams for use in conventional quantitative or consequence-based risk assessments. The goal is to provide the industry with a robust technical approach and general framework for evaluating the risks to subsea infrastructure from accidental pipeline releases during pipelay operations.