Research On Optimization Planning Of Micro-energy Systems For Offshore Oil And Gas Platforms

Offshore oil and gas platforms are far away from the coast,and the environment is complex,which requires power,heat,gas,water and other energy and material supply,forming a relatively complete and independent integrated energy system.Because the capacity of such systems is generally within a few MW to dozens of MW,it can be called a Micro integrated energy system or Offshore Micro Integrated Energy System(OMIES).As offshore oil and gas platforms are developing towards multi-platform collaboration,cluster development and multi-energy utilization,the existing planning methods can no longer meet the requirements of economy,environmental protection and stability of offshore oil and gas platforms.At present,the planning of the energy supply system for offshore oil and gas platforms has the following problems:(1)the energy utilization form is single and the energy efficiency is low;(2)considering only the economy of the planning,the waste gas is discharged arbitrarily and the pollution is serious;(3)production of associated gas is unstable,and supply and demand are difficult to balance;(4)lack of gas and power storage equipment,and energy scheduling flexibility is insufficient.In order to improve the current situation of low energy utilization and serious pollution of offshore oil and gas platforms and overcome the planning difficulties of uncertainty and flexibility,drawing on the research results of regional energy system(RIES)planning,this paper combines the operation characteristics of offshore oil and gas platforms,introduces new equipment,energy saving and emission reduction devices and methods recognized in the field of offshore oil,gas and ship engineering,and proposes an OMIES which emphasizes multi-energy complementarity,waste heat cascade utilization and electric-thermal-gas coupling.On this basis,considering the influence of the uncertainty of production process system on its planning,the OMIES multi-objective programming model for coordinating economic and environmental benefits is constructed and solved by the proposed algorithm.Full-text content includes:In the first part,the domestic and international literatures about RIES and OMIES are summed up,and the researches about RIES planning method are introduced.Moreover,the prospect of the application of OMIES is described,as well as the work we do on this problem.Secondly,the basic structure of the offshore oil and gas platform energy supply system is described in detail,and the OMIES is constructed by introducing energy conversion equipment and energy saving and emission reduction devices recognized in the field of marine engineering.Aiming at the close coupling relationship between platform production process system and energy supply system,a generalized energy and material flow model(GEMFM)was proposed,and the basic characteristics,modeling process and modeling conditions of the GEMFM are discussed in detail,which laid a foundation for the analysis of energy conversion and distribution relationship and uncertainty analysis of OMIES.Thirdly,in view of the planning status of low utilization rate of residual heat,associated gas exhaust waste and large carbon emission of offshore platforms,from the perspective of integrated energy system optimization planning,the electrical-thermal-CO2 coupling model of OMIES was established based on energy hub concept,the OMIES multi-objective programming model was established with the total cost and the minimum CO2 emissions as the optimization objectives,and the energy flow balance of gas,electricity and heat as the constraints.The Pareto-optimization set was obtained by NSGAII algorithm,and then the best planning scheme was defined according to the relevant specifications of offshore engineering design.Through application of the proposed method in the OMIES of a group of offshore oil and gas platforms,the effectiveness and feasibility are verified.Fourthly,based on the GEMFM,the energy-material coupling relationship of the energy supply system and the production process system as well as the interaction between the input end and the output end were quantitatively characterized.Considering the energy-material balance constraints and the uncertainties of production system,a multi-objective stochastic planning model for the offshore integrated energy system is established,and a Monte Carlo simulation-based NSGA-II algorithm is proposed to solve the model.Finally,the validity and feasibility of the proposed methodology are demonstrated through an offshore oil and gas platform in Bohai,China.Fifthly,in view of the unstable production of associated gas,less gas and electricity storage,and imbalance between supply and demand,this paper establishes an electricity and associated gas combined energy storage model,and considers the influence of production process system uncertainty on the OMIES.Large fluctuations are regulated by the associated gas storage,while small fluctuations are regulated by the electric energy storage system.At the same time,based on the dual uncertainty theory,the fuzzy random programming model of the OMIES is constructed,and the fuzzy random NSGAII algorithm is proposed to solve it.Finally,an example of an offshore oil and gas platform in Bohai is taken as an example to verify the feasibility and effectiveness of the proposed model and method.