Reservoirs History Matching And Production Optimization Study Based On Multi-objective Optimization Algorithm

The primary target of oilfield development is to maximize economic profits without entailing excessive costs.There are some problems in the development process,such as,interlayer conflict,areal conflict as well as interior conflict,due to the strong heterogeneity of the reservoir.In order to overcome these problems,it is necessary to build an accurate geological model and design the best injection-production development plan to maximize sweep efficiency and realize equilibrium displacement.Building an accurate geological model needs history marching which has many multiple matching indexes and minimizes the difference between the matching model and prior model.Thus,history matching is a multiobjective optimization problem,which is suitable for multi-objective optimization method.It is necessary to optimize the reservoir production after obtaining the geological model.There are various demands for reservoir production optimization,which mean that objective function corresponding to different requirements should also be different.Therefore,production optimization is also a multi-objective optimization problem.Therefore,this paper carried out research on multi-objective historical matching and production optimization based on multiobjective optimization theory.Firstly,the paper proposes a multi-objective water cycle algorithm(MOWCA-Adaptive),which can automatically control the population number,after investigating and comparing some multi-objective problem optimization algorithms(such as MOPSO,NSGAII,MOWCA).This algorithm can meet the needs of oilfield development because of its high resource utilization and fast optimization speed.Then,this paper combines this algorithm with historical matching to form a new multi-objective historical matching method.Compared to the singleobjective historical matching method,the method does not have weight coefficient,the matching results are not subject to subjective influence and the model set contains the combination of weight coefficient of ownership,which makes the matching result more accurate and reliable.Finally,this paper combines the multi-objective optimization algorithm with production optimization to form two different types of multi-objective injectionproduction optimization methods.The first one is that,considering a single model,multiobjective zoning optimization is carried out according to the characteristics of different development objectives in different areas of the reservoir,which could achieve the optimal goal of multiple areas of the reservoir.The second one is that,considering multiple models,uncertainty interval optimization is carried out for the results of historical matching,which could reduce the uncertainty of the whole reservoir development process.In addition to validating the proposed method with the theoretical model,this paper also validates the multi-objective historical matching and zoning optimization method with X actual oilfield.The results show that the proposed new multi-objective historical matching method can effectively reduce the uncertainty of matching and improve the reliability of the results and the multi-objective zoning optimization method can achieve the purpose of optimizing the demand of different regions respectively.