Yuxi Wang

The idea of this paper comes from the need for a practical layout design for the subsea pipe line network and the power transmission network of offshore wind farms with subsea cables, which are both subsea transmission networks with line-shaped conduction structures. In this paper, this practical need is treated as an location-allocation problem, with the objective of minimizing the total cost, and a mixed-integer linear programming model (MILP) for layout optimization is developed. Through the model, the locations of service centers and theit corresponding sizes, the allocations between customers and service centers, as well as the transmission routes can all be figured out. This work makes two key contributions. First, facilities’ capacity restrictions and the avoidance of subsea obstacles are both integrated, making the description of the layout closer to practical situations. Secondly, a “global to local” search process based on the Delaunay triangulation method is constructed to solve the model, resulting in a high-quality solution. An offshore field layout design scenario is taken as a case study, through which the validity, feasibility, and stability of the proposed model, as well as the solution strategy, are presented. Furthermore, in the case study, the effect of the manifold number on the layout optimization is analyzed, indicating the flexibility of the model’s applications.

Mitigating greenhouse gas (GHG) emissions to curb climate change has become a consensus among international community. Refining is one of the major industries with high energy consumption and high emissions, which is responsible for 4-10% of global carbon dioxide (CO2) emissions and approximately 25% is generated by fluid catalytic cracking (FCC) units. The flue gas discharged from FCC units has a high CO2 content, presenting potential for methanol and electricity co-production production when the methane in the dry gas is considered. To unlock this green chance for enterprises, we designed a methanol production system that uses the CO2 recovered from the flue gas of fluid catalytic cracking (FCC) unit in a refinery and the CH4 separated from dry gas as feed stock (hydrogen to be added from an internal hydrogen production unit of the refinery). We analyzed economic feasibility of the process, the results show that the developed system is economically feasible for annual methanol yields of 1.0-2.5 Mt and the internal rate of return increases by 8.3%.

Product presentation video, an essential medium for online product presentation, mainly conveys product information to consumers. The quality of product information expression will affect consumer's purchase experience, even purchase decisions. But many video production novices often have difficulty assessing the effectiveness of their videos and doing optimization. Thus, we adopt information mediums' perceived usefulness and perceived ease of use as assessment indicators, and propose an automatic explainable assessment method. The method is based on the combined use of the extreme gradient boosting algorithm and SHapley Additive exPlanations method, which is implemented to assess video samples and generate explanations on the assessment results. We create a product presentation video dataset for development and evaluation. The results show that our method can assess video effectively, and provide insights into the shortcomings of videos' production like experts.

The increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long-distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, pressure, temperature, flowrate, and length of each flowline vary, leading to different thermal performances of the transported fluid. Therefore, the insulation coating should be carefully designed from the overall perspective to minimize the total material volume, thus reducing the cost. In this paper, an optimization model for the insulation material volume of a rigid subsea flowline system is proposed. Then, the best insulation thickness of each subsea flowline can be determined under given flow parameters and temperature requirements. The factor that defines the temperature drop from the riser base to the top termination is introduced and analyzed. There is a proper temperature drop factor associated with the insulation material volume for subsea flowlines, as well as a proper insulation capacity for the risers. This optimization model can define the subsea system insulation and provide reliable results for cost estimation.

The increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, pressure, temperature, flow rate and length of each flowline vary, leading to a different thermal performance of the fluid inside. Therefore, the insulation coating should be carefully designed from the overall perspective to minimize the total material volume, thus reducing the cost. In this paper, an optimization model for the insulation material volume of a wellhead-manifold-FPSO production system is proposed. Then, the best insulation thickness of each sub-sea flowline can be determined under given flow parameters and temperature requirements. The factor that defines the temperature drop from riser base to the top termination is introduced and analyzed. There is a proper temperature drop factor associated with the insulation material volume for subsea flowlines, as well as a proper insulation capacity for the risers. This optimization model can define the subsea system insulation and provide reliable results for cost estimation.

The development of a subsea field implies a complex design procedure with very high costs involved. The combination of low oil price, harsh environment, very deep waters and high drilling costs has emphasized the need for new ideas to reduce both CAPEX and OPEX. The paper considers different subsea layout scenarios of a typical deep water field. Each scenario is optimized considering pipeline length, equipment cost and flow assurance. The software QUE$TOR is then applied to estimate the cost of each optimized scenario. Two of them are selected for further studies, FPSO connected to six slots subsea manifolds, and subsea separator connected to eight slots cluster manifolds with tie-back to an existing platform. The latter representing a hybrid solution based on the subsea-to-shore concept. Cost and technical feasibility are considered in order to evaluate the two scenarios.