Abstract
Prior surface provision tie-in activities of new pipeline project connecting four pumping stations A-B-C-D, an engineering study must be performed and consolidated with a sequentially-safe field execution. The main challenge is to deliver production using only one booster pump from pumping station A up to D through in total 54 km multi-segments-size of 16"-12"-14" un pig-able subsea pipeline with a limited operating pressure of 210 PSIG. The unexpected production losses must be predicted and prevented during thses activities. Regarding those field limitations, sensitivity analysis has being used as an approach to identify any variables which are important to mao out the likelihood of multiple scenarios, identify detail surface interdependencies, and develop operational subtasks all of which are needed to be done simultaneously. The analysis has being done using multiphase flow set up under nodal-based iteration to calculate and deliver flow profiles covering whole pipeline section length. In general, there are four different multi pattern flows which are well identified under the study: bubble, transition, slug, and intermittent flow.
This paper describes out study and development of operational subtasks which are needed to be done on the working field in order to prevent production losses during shut down moment of provision tie-in execution. Based on the results, a production of 20k BFPD and 2k BOPD was feasible to be delivered without any side effect of process upset along all pumping stations. Those subtasks were focusing on pressure preservation, intermittent flow management, robust operational enforcement safely, and integrity concern in mature pipeline and topside facilities.
The novelty of this robust sensitivity analysis is in the ability to predict pipeline pressure drop while maintaining the integrity due to MAOP (Maximum Allowable Operating Pressure) limitation. Multiple scenario of safe delivery modes were furthermore precisely identified. This success story can be implemented on future cases along mature offshore facilities.
