The Benefit of Integrated Asset Modeling and Optimization in Evaluating Production Strategies under various Oil and Gas Price Scenarios

Abstract

Abstract The decrease in oil and gas prices results in a huge impact in the oil and gas company. This paper discusses the importance of integrated asset modeling and optimization of oil and gas fields under various oil and gas price scenarios. The integrated model is defined as simulation runs from the reservoir up to the surface process and continues with an economic evaluation. Various field models under different production strategies are presented in the paper and evaluated based on the integrated asset model. The reservoir models are a gas condensate reservoir under gas cycling and an oil reservoir under water alternating gas (WAG) injection production strategies taken from SPE 3 and SPE 5 comparative projects. Derivative free optimization methods are used to find the best operating conditions for the field. The optimization objective is to maximize economic key performance indicators, such as net present value, and to minimize cost, such as gas injection cost. The decision variables are gas injection fraction, gas injection time, water injection rate and WAG time. Using integrated system modeling, the operating parameters can be determined accurately considering reservoir and surface process capabilities. The optimization results showed that optimum gas injection time is longer during high oil prices compared to low oil prices for the gas condensate reservoir under gas injection. The oil and gas prices are fluctuating in a certain cycle over time, and the dynamic fluctuations are accommodated in the economic model. Many reasons are behind the dynamic fluctuations of oil and gas prices. The fluctuations will have an impact on company production strategies. The economic model will be simulated under very high, high, intermediate, low and very low price scenarios. For each scenario, the model will be run in the integrated modeling and reservoir only modeling. A scenario of varying the ratio of oil to gas price is also included in the analysis. Different oil and gas prices will lead to different management decisions during the field lifetime. A conservative production strategy, meaning when the field is simulated separately part-by-part, could mislead field production decisions. Based on the reservoir simulation, the liquid production might flow easily from the reservoir to the surface. However, based on the surface simulation, the well might be shut–down due to flow restriction on the surface. This paper presents the important concept of the integrated model and optimization under dynamic oil and gas prices. The oil and gas prices have an influence in determining production parameters. The integrated model that is used in the paper is flexible and can be replaced with another reservoir model, surface process model, or economic models. Keywords: Integrated asset model and optimization; various oil and gas price scenarios, production strategies.