Optimal Control of Field Development in a Closed Loop
Authors: Zakirov E. S. , Zakirov S. N. , Indrupskiy I. M. , Lyubimova O. V. , Anikeev D. P. , Shiryaev I. M. , Baganova M. N. 
Published: October 2015

The problem of optimum field development management has been always important, but for the recent years it acquired a special practical value. Intelligent field control systems, "smart" wells and other technical achievements open up new possibilities for maximizing recovery without any additional costs for drilling and changes in development system. This task is of special relevance for hard-to-recover hydrocarbons – deposits with low-permeable heterogeneous reservoirs, high water-cut fields, heavy oil reservoirs, remaining reserves of low-pressure gas fields, gas condensate deposits, oil rims, etc.

Today field development management is known more as a technical problem of operating and measuring hardware implementation, while scientific aspects are insufficiently developed. The most accurate definition of this problem, representing its practical value, consists in the management of development in the closed loop, when assimilation of data from various sources is continiuosly followed by production optimization based on the history-matched 3D model. Production dynamics forecasting for the set of production/injection controls on wells or separate intervals of "smart" wells is carried out in multiphase non-stationary statement on a sector or full-scale 3D model. To incorporate permanently incoming field information, the automated adaptation (history matching) of a 3D model to the actual well operation and testing data is carried out periodically.

Authors have implemented a geologically consistent algorithm for automated 3D model history matching, based on the effective modern methods of the optimum control theory. In contrast to traditional approaches, not individual properties of reservoir zones are adjusted in the history matching procedure, but rather initial parameters of anisotropic geostatistical fields and petrophysical relations, taking into account the facial model of the reservoir. The hhistory-matched 3D model is used for searching at each time step for the optimal well operating controls maximizing an integral quality criterion – e.g., discounted oil production or given criterion of economic efficiency for the forecast period. Field surface facilities group limitations on fluids production/injection volumes and individual limitations of wells on operating pressures are considered. The efficiency of optimization algorithm is as well granted by use of the modern optimum control theory methods.

The developed algorithms for soluton of field development management problems in the closed loop are implemented in the authors' in-house software SimMatch®. Within the forward problem solution it implements the extended black oil model and is comparable in functionality to the main modules of commercial simulators. As an example of the implementation of the proposed approach, several cases of geologically consistent history matching and optimum waterflooding control for deposits with highly heterogeneous anisotropic fields of reservoir properties (both flow and capacity parameters) are presented in the paper.

For the first time, the approaches developed by the authors provide the solution for closed-loop development management in the complete and focused-on-practical tasks problem statement. The developed methods and algorithms implement the automated procedure for adaptation (history matching) of a 3D model to actual data without violation of the original geological principles of the model. They make possible to control reduction in uncertainty of the forecast field development dynamics, taking into account incoming field data and perform proactive optimum management of wells or separate intervals of "smart" wells operation for maximizing integrated output from field development.