Pitfalls of Open Ended Front End Engineering Design

Abstract Several essential parameters, that often form the basis of design activities performed during Front End Engineering Design (FEED), are oftenly modified at late stages of the FEED process resulting in the transfer of various critical activities to the subsequent Engineering, Procurement and Construction (EPC) stage, rendering the FEED open-ended. This paper presents the impact of an open-ended FEED on EPC projects, and provides an approach to enhance the overall effectiveness of Oil and Gas project execution. Basic Engineering, performed during FEED, comprises of various critical design activities such as Simulations, Material Selection and Sizing Calculations. Process simulations are prepared based on the extreme governing cases such as maximum flowrates extracted from the production forecast. Moreover, equipment material is selected to suite the specified reservoir composition since different chemical component combinations exhibit varying properties and behaviors. Furthermore, equipment size is calculated to satisfy the defined battery limits’ conditions such as Temperature and Pressure. The critical activities that are carried forward from FEED stage impose amplified risks of design variations during EPC stage, which may have significant schedule and cost implications on the EPC project. In recently executed EPC projects, the reservoir composition, production forecast, and battery limits conditions were modified after the completion of the FEED, which resulted in the reworking of various basic engineering activities that caused significant delays in the issuance of detailed engineering deliverable and the procurement of critical Long Lead Items (LLI). The alterations to the production forecast such as elevated water flowrate resulted in the reverification of the governing cases and the mitigation of the impact on the facility design. Additionally, the changes to the fluid composition such as increased Hydrogen Sulphide content led to numerous adjustments to equipment material specifications and coating requirements. Furthermore, the revision to the battery limits conditions such as Maximum Deadhead Pressure required several amendments to the size of control instrumentation and safety equipment. Clients are recommended to adopt the strategy of providing fixed and clear essential parameters during FEED stage in order to minimize the reworks/revalidations during EPC stage, enhancing the overall success of the Oil and Gas project. This paper aims to raise awareness of the risks associated with an open-ended FEED on EPC project execution. This paper also presents valuable suggestions and mitigation strategies that will assist all Oil and Gas project stakeholders in effectively optimizing their resources, enhancing the efficiency and profitability of their projects.