Real-time Operation of Reservoir Systems, Information Uncertainty, System Representation and Computational Intractability
Real-time Operation of Reservoir Systems, Information Uncertainty, System Representation and Computational Intractability

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Published: 2000

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Modeling real-time reservoir operations and developing optimal rules are formidable tasks considering a number of issues that need to be addressed within optimization and simulation models. The issues range from uncertain system inputs to implementation of operating rules in real-time. This dissertation addresses some of these issues that are relevant at different stages of real-time reservoir operation process. These issues are: (i) information uncertainty; (ii) system representation; and (iii) computational intractability. Realtime operation models are developed in the present research for single and multiple reservoir systems while addressing these issues in that order. Uncertainty generally associated with system variables in a variety of forms is a main hurdle in developing a proaches for optimizing reservoir operations. Explicit and implicit stochastic approaches based on traditional probability theory concepts cannot always handle all the uncertain elements of reservoir operation. Approaches to handle imprecise information are required as much as methodologies to address the issue of lack of information. The former issue described as information uncertainty in this thesis is addressed using fuzzy set theory. Mathematical programming models are developed under fuzzy environment to handle imprecise and uncertain components of reservoir operation problem dominated by an economic objective. The concept of 'compromise operating polices' is proposed and its utility is proved. Representation of physical system in mathematical programming formulations affects the extent to which the physics of the problem is captured and nature of the solutions that can be obtained. Tradeoffs between exhaustive representation and optimal solutions can be identified. Operation of a multiple reservoir system is considered to develop formulations of varying degree of system representation. A Mixed Integer Non-Linear Programming (MINLP) Model with binary variables is developed to a speci.

Analysis of Real-time Reservoir Monitoring
Analysis of Real-time Reservoir Monitoring

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Published: 2006

Total Pages: 84

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The project objective was to detail better ways to assess and exploit intelligent oil and gas field information through improved modeling, sensor technology, and process control to increase ultimate recovery of domestic hydrocarbons. To meet this objective we investigated the use of permanent downhole sensors systems (Smart Wells) whose data is fed real-time into computational reservoir models that are integrated with optimized production control systems. The project utilized a three-pronged approach (1) a value of information analysis to address the economic advantages, (2) reservoir simulation modeling and control optimization to prove the capability, and (3) evaluation of new generation sensor packaging to survive the borehole environment for long periods of time. The Value of Information (VOI) decision tree method was developed and used to assess the economic advantage of using the proposed technology; the VOI demonstrated the increased subsurface resolution through additional sensor data. Our findings show that the VOI studies are a practical means of ascertaining the value associated with a technology, in this case application of sensors to production. The procedure acknowledges the uncertainty in predictions but nevertheless assigns monetary value to the predictions. The best aspect of the procedure is that it builds consensus within interdisciplinary teams The reservoir simulation and modeling aspect of the project was developed to show the capability of exploiting sensor information both for reservoir characterization and to optimize control of the production system. Our findings indicate history matching is improved as more information is added to the objective function, clearly indicating that sensor information can help in reducing the uncertainty associated with reservoir characterization. Additional findings and approaches used are described in detail within the report. The next generation sensors aspect of the project evaluated sensors and packaging survivability issues. Our findings indicate that packaging represents the most significant technical challenge associated with application of sensors in the downhole environment for long periods (5+ years) of time. These issues are described in detail within the report. The impact of successful reservoir monitoring programs and coincident improved reservoir management is measured by the production of additional oil and gas volumes from existing reservoirs, revitalization of nearly depleted reservoirs, possible re-establishment of already abandoned reservoirs, and improved economics for all cases. Smart Well monitoring provides the means to understand how a reservoir process is developing and to provide active reservoir management. At the same time it also provides data for developing high-fidelity simulation models. This work has been a joint effort with Sandia National Laboratories and UT-Austin's Bureau of Economic Geology, Department of Petroleum and Geosystems Engineering, and the Institute of Computational and Engineering Mathematics.

Analysis of Real-time Reservoir Monitoring
Analysis of Real-time Reservoir Monitoring

Author: Scott Patrick Cooper

Publisher:

Published: 2007

Total Pages: 86

ISBN-13:

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The project objective was to detail better ways to assess and exploit intelligent oil and gas field information through improved modeling, sensor technology, and process control to increase ultimate recovery of domestic hydrocarbons. To meet this objective we investigated the use of permanent downhole sensors systems (Smart Wells) whose data is fed real-time into computational reservoir models that are integrated with optimized production control systems. The project utilized a three-pronged approach (1) a value of information analysis to address the economic advantages, (2) reservoir simulation modeling and control optimization to prove the capability, and (3) evaluation of new generation sensor packaging to survive the borehole environment for long periods of time. The Value of Information (VOI) decision tree method was developed and used to assess the economic advantage of using the proposed technology; the VOI demonstrated the increased subsurface resolution through additional sensor data. Our findings show that the VOI studies are a practical means of ascertaining the value associated with a technology, in this case application of sensors to production. The procedure acknowledges the uncertainty in predictions but nevertheless assigns monetary value to the predictions. The best aspect of the procedure is that it builds consensus within interdisciplinary teams The reservoir simulation and modeling aspect of the project was developed to show the capability of exploiting sensor information both for reservoir characterization and to optimize control of the production system. Our findings indicate history matching is improved as more information is added to the objective function, clearly indicating that sensor information can help in reducing the uncertainty associated with reservoir characterization. Additional findings and approaches used are described in detail within the report. The next generation sensors aspect of the project evaluated sensors and packaging survivability issues. Our findings indicate that packaging represents the most significant technical challenge associated with application of sensors in the downhole environment for long periods (5+ years) of time. These issues are described in detail within the report. The impact of successful reservoir monitoring programs and coincident improved reservoir management is measured by the production of additional oil and gas volumes from existing reservoirs, revitalization of nearly depleted reservoirs, possible re-establishment of already abandoned reservoirs, and improved economics for all cases. Smart Well monitoring provides the means to understand how a reservoir process is developing and to provide active reservoir management. At the same time it also provides data for developing high-fidelity simulation models. This work has been a joint effort with Sandia National Laboratories and UT-Austin's Bureau of Economic Geology, Department of Petroleum and Geosystems Engineering, and the Institute of Computational and Engineering Mathematics.