Entity

Time filter

Source Type

Total, Netherlands

Toinet S.T.S.,E and P Angola | Souvannavong V.S.V.,CGGveritas | Colnard O.C.O.,CGGveritas
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

4D pre-stack inversion is used in the industry to image reservoir changes due to production and injection, and to make reservoir management decisions in order to optimize hydrocarbon recovery. We present an innovative workflow to prepare, constrain and compute 4D pre-stack inversion attributes. Specific properties of the studied field (huge time-shifts due to gas coming out of solution, various turbiditic contexts) implied building a composite warping result, filtered using a 4D mask to build the initial monitor model for 4D inversion. The pre-stack 4D inversion workflow not only integrates seismic information, but also well information, used to discriminate sand from shale during the 4D mask building, and a 4D rock-physics model. Applied to simulated reservoir properties, the rock-physics model defines a range of relative density and velocity variations in which the inversion results can vary. Moreover, because waterbearing sands are hard to discriminate from shales in some of the field reservoirs using a cross-plot of P and S impedances, information from the reservoir grid was also introduced to help locating water-bearing sands in the 4D mask. Preliminary analyses of 4D inversion attributes show an improved image compared to previous 4D attributes. © 2010, European Association of Geoscientists and Engineers. Source


Ceragioli E.,E and P Angola | Bovet L.,E and P Angola | Guilbot J.,E and P Angola | Toinet S.,E and P Angola
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

During 2008 and 2009, the first industrial scale Ocean Bottom Nodes (OBN) project over a fully operational production environment was completed by Total on the Dalia oilfield, Block 17, deep offshore Angola. A repeatability test was also performed as part of the operations. Block 17 geophysical response is characterised by weak absorption effects: frequencies up to 120Hz are often used for reservoir characterisation and monitoring. OBN are passive recording systems and source-to-receiver travel times must be reconciled after acquisition is completed. For these reasons, during all operations, great efforts were addressed to any possible cause of time misalignments, since the smallest errors could actually reflect in degradation of thin sedimentary features. When compared to streamer results, OBN processed data exhibit some minor loss in high frequency content but a clear gain towards the lower end of the spectrum. We demonstrate that OBN and streamer data can successfully be merged and that qualitative and quantitative 4D interpretations are possible, in good agreement with the petrophysical knowledge of the Dalia complex. Finally, the repeatability test validates the business model by which selected targets of a deep offshore field can effectively be monitored by fairly limited patches of retrievable OBN stations. © 2010, European Association of Geoscientists and Engineers. Source

Discover hidden collaborations