Modern reservoir development could not happen without building and using 3-phase 3-D simulation models and predicting the future performance of the field using powerful computer technologies. Long term production and injection profile forecasts for the Azeri field have been carried out through usage of simulation models from 2001. Since production from 2005 Azeri models have been history matched on an annual basis. While matching the model data to the actual field observed data, surveillance and performance learnings have been an integral part of the process in order to obtain representative and satisfactory results.In the current work, the challenges and problems faced, as well as the success of the history match process for the Azeri field are described. Along with discussion of applied techniques and obtained results, recommendations on matching complex reservoir simulation models based on several years experience of history matching process in the Azeri field are offered.
Accurate and timely information is essential to monitor, control and manage reservoir and well performance. At the present, production and reservoir engineers as well as production geologists have a challenging task of managing oil and gas reservoirs. This requires a broad knowledge of the reservoir supported by fit-for-purpose integrated technologies and real time access to relevant data. In the Azeri-Chirag-Gunashli (ACG) field development, downhole information is commonly acquired through uses of LWD (logging while drilling) tools to obtain a standard log suite and obtain formation pressure measurement, production logging and well testing. In addition, Downhole Temperature Sensors (DTS) has been installed on someACG wells to provide continuous temperature readings across the reservoir so as to obtain critical understanding of reservoir behaviour, connectivity and fluid distribution.ACG structure is located in the offshore of Azerbaijan part of the South Caspian Basin (Figure 1). The structure is an elongate anticline with 3 main accumulations ( Figure 2): 1). Shallow Water Gunashli (SWG) is in the northwest operated by SOCAR and on production since 1980; Deep Water Gunashli (DWG) extended from SWG to the east and became a part of ACG field operated by AIOC with production start-up in 2008; 2). Chirag situated in the centre of the structure that has been on production since 1997; 3). Azeri is in the south east which is in production since 2005(Wethington et al., 2002. ACG structure is complicated by the presence of several mud volcanoes and series of faults and seismic elements cutting field along the length. Development of field is under 30 years PSA that expires in 2024.This field contains 16 hydrocarbon-bearing reservoirs of Pliocene age. Each of the reservoirs is regionally identifiable, laterally extensive and correlatable within the long distance. They comprise stacked fluvial-deltaic sandstones deposited by the paleo-Volga delta, flowed from the north to the south into the lacustrine South Caspian Basin.The main producing interval in Azeri field is a Fasila reservoir that has been subdivided into 5 sublayers (Fasila A,B,C,D, & E) based on the first appraisal well stratigraphy. A stratigraphic section of Fasila reservoir from one of ACG wells shown on Figure 3 illustrates high net-to-gross (NTG) Fasila B and Fasila D sublayers separated by lower NTG Fasila A, C and Fasila E layers.Azeri development proceeds under crestal gas and peripheral water injection support. Therefore understanding of compartmentalization of the structure plays significant role in production efficiency.
The Azeri-Chirag-Gunashli (ACG) oil field is located in the hydrodynamic environment of the South Caspian Basin (SCB). The presence of lateral pressure variations in such systems results in tilted hydrocarbon-water contacts. Besides the tilt, the eastern part of the field demonstrates unexpected fluid contacts observed from several appraisal and development wells. These unexpected contacts are not in accordance with tilts and cannot be explained by hydrodynamism only.Proposed solution to explain contact anomalies in the eastern part of the structure is to analyze the effects of permeability barriers on fluid contacts in hydrodynamic environment. Analysis is done through mechanistic model simulations. It was determined that barriers influence the contacts in hydrodynamic aquifer environment and it is possible to explain aforementioned contact anomalies by plausible barrier arrangement.Incorporation of study results into the Azeri full field model (FFM) resulted in better pressure and saturation match.
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