Risk Analysis for Uncertainties Management of Integrated Production Optimisation and Field Potential Evaluation

Abstract Production optimization of hydrocarbon fields is a complex task, due to the high number of processes involved and their synergy. It is therefore challenging to manage an integrated production system, comprising the reservoir and the production wells, the gathering system, and the process plant. The optimization process is driven by input data subjected to uncertainties due to variability, observational errors, and lack of up-to-date measurements. As a consequence, the aforementioned uncertainties are carried out through the simulation process up to final results. This work presents a workflow for oil & gas production optimization under uncertainties, that is structured in three phases. In the first phase, the integrated optimization process with powerful evolutionary algorithms takes place. The result is an optimized field configuration characterized by a deterministic production increase in respect to the initial production. After having identified the uncertain input variables in the optimization process, a Monte Carlo simulation for the optimized field configuration is performed. In this second phase, the input data are modelled through statistic distributions, and the obtained result is a probabilistic distribution of the production increase. The third step is a detailed analysis of the system constraints to evaluate the behaviour of the optimized configuration. In addition, a methodology to choose an alternative setting of the production field, that allows to increase the system reliability, is presented. The integrated workflow has been applied on a case study. The results obtained show that is extremely important to identify and quantify the uncertainties involved in a hydrocarbon production system for the evaluation of its potential production, and to verify the compliance with its constraints. Applying a configuration when a high degree of uncertainty is present may be hazardous and unsafe. The proposed workflow is an important tool to evaluate the field potential under uncertainties, optimize production, improve operations and system reliability, and support the decision-making process. Introduction Oil and gas production optimization is a field of extreme importance, since oil demand is continuously increasing, and many reservoirs currently in production are experiencing a decrease in production rates. The high number of processes involved and the synergy between them make the optimization of hydrocarbon fields a very complex task. It is therefore of primary importance to manage the challenges associated with an integrated production system, comprising the reservoir and the wells, the gathering system, and the process plant. In order to holistically optimise the production system the proposed integrated approach aims to combine subsurface models, surface production and engineering models in a single asset management tool.