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10th International Congress of the Brazilian Geophysical Society
- Conference date: 19 Nov 2007 - 23 Nov 2007
- Location: Rio de Janeiro, Brazil
- Published: 19 November 2007
481 - 484 of 484 results
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Improving the translation of 4D seismic attributes into reservoir properties
More LessThe optimization of the quantitative seismic data interpretation process is a key factor for reservoir
characterization and monitoring. In this paper, we show the results of a methodological investigation where Neural Network and Discriminant Analysis, two possible tools to incorporate the 4D seismic attributes in the quantification of saturation changes during the production of a reservoir, where analyzed. A special focus was applied to the evaluation of the impact of the quality and the amount of the calibration data to the final result, showing the
pseudo-well technology as a good alternative to improve the process.
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4D seismic monitoring of the Girassol field (Angola): enhanced interpretation of production mechanisms through impedance inversion
Authors Christian Hubans and Philippe Berthet4D-seismic is regarded with increasing interest as a strategic source of dynamic information, and as an added
value monitoring tool to optimise reservoir management decisions. The actual value of the 4D-seismic information relies on the possibility to bring it early enough in the project life to impact the development plan, and to
participate in the construction of a reliable Reservoir Model. Two seismic monitors have been acquired on Girassol-
Jasmim, as part of a seismic monitoring project. The 4D processing and interpretation workflow we have
developed has allowed us to start exploiting the essential of 4D information very early after the monitor acquisition.
This key dynamic information has been used to constrain the reservoir model history match. The integration of 4D
information has impacted fundamental decisions, like the drilling of a development well on a poorly drained area
identified on 4D data. Girassol-Jasmim 4D experience proves that time-lapse seismic brings added-value information all along the project life. 4D can effectively help optimising the development wells locations. The additional reserves associated to wells targeting undrained panels, the optimisation of development well locations and the increase in reliability of the Reservoir Model (basis for the reservoir management decisions) largely justify 4D expenses. The main goal of this work is to deconvolve, at least partially, pressure and saturation changes from 4D data. To advance in this direction, we have inverted seismic traces to extract reliable P and S time-lapse impedance changes through 4D-seismic multi-offset simultaneous inversion. Combined with the results of time shift
inversion process we have been able to split the P Impedance changes into Velocity and density parts. As Pressure does not impact the density in first approximation it is theoretically possible to approach pressure and saturation evolutions within the reservoir. A first step of well inversion tie have been performed and shows very consistent results..
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4D Seismic Interpretation in the Marlim Field, Campos Basin, Offshore Brazil
The growing application and acceptance of 4D or timelapse seismic technique as a key reservoir management
tool has been well documented. The technique has been successfully applied to numerous mature fields in order to
optimize reservoir production and recovery. This paper will describe such a case study on the Marlim Field where
the application of 4D seismic has contributed significantly to critical reservoir management decisions. The giant Marlim field is located on the eastern Brazilian coast in water depths varying from 600 to 1200m. The reservoir is characterized by an unconsolidated sandstone turbidite related to the regressive mega sequence of the Brazilian eastern continental margin. It is the largest producing oilfield in Brazil (average 450.000 bpd), with the original oil-in-place volume of 6.4 billion STB. Production started in 1991 and injection of water in 1994. Three seismic surveys cover the Marlim Field. The first one was Confidential Page 1 3/27/2007acquired in 1986, the others in 1997 and 2005. The most recent survey was acquired using WesternGeco´s Q- Marine acquisition system and was specifically acquired for reservoir monitoring and characterization purposes. Analyses of the 4D results started in June 2006 after parallel processing of the 1997 and 2005 datasets. This paper will highlight how the results of the 4D interpretation are being used to make critical reservoir management decisions with greater confidence and
reduced risk.
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Monitoramento Sísmico da Produção em Marlim Sul
Marlim Sul field, situated in Campos Basin, Brazil, applied its first time-lapse seismic acquisition in 2005. The main prime purpose of this 4D study is to understand the flow path of the injection water in the reservoirs. The seismic data were acquired by a streamer steering system and received special attention in terms of velocity analysis and crossequalization process. The 4D results have shown that the water paths are less regular than expected from flow simulation, which indicate the presence of barriers and flow baffles and trends in rock
permeability. Also, it was possible to identify swept and non-swept areas in the reservoirs, which allow studies of new well locations and the re-evaluation of present projects in the field.
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