Ravva | 3D Geocellular Model


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Ravva - Cairn’s first development success story has been the bedrock of innovation, and the foundation of our success story in the country and the region. Ravva, which in Sanskrit and Telegu means “diamond” showcases the journey of growth that Cairn has been able to achieve in its business. Incidentally, Ravva is the only field in India to get such a unique name indicating the belief of the nation in it.

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Ravva | 3D Geocellular Model

  1. 1.               RAVVA Celebrating 16 Years of Technical Excellence Innovating Development | 3D Geocellular Model
  2. 2. Ravva | Innovating DevelopmentRavva 3D Geocellular ModelBuilding geological models is one of the mostimportant phases in field development. The staticdescription both in terms of geometry andpetrophysical properties coupled with structuralparameters and fluid contacts are the most criticalfactors used to develop the field optimally andimprove recovery from the reservoirs. The primarygoal of building a static model is to capture thesubsurface heterogeneity both vertically andhorizontally at the well and field scale, which canbe used as a tool for accurate estimation ofhydrocarbon in-place, well planning, fielddevelopment planning, and reservoir management for optimum recovery.Seismic data contains a wealth of information about the reservoir properties between the wells, and alsoaway from the well locations. Well data and seismic data are complementary to each other. Well data hasa very high vertical resolution, while the seismic data has higher spatial resolution. The combination ofwell data and seismic characters help in representing the reservoir in 3D space more accuratelyparticularly between the well and away from the well. The variation in the lithological and petrophysicalcharacteristics and fluid content of the reservoir rock has an impact over the recorded seismic signal andthis is used to interpret rock characteristics during inversion.The middle Miocene reservoirs such as M20, M30, M32, M33 and M34 are the main reservoirs producingin the RAD and REFB blocks of the Ravva Field. The 3D static geocellular model building activity wascarried out in 2004 for the first time for middle Miocene reservoirs of Ravva. Fine scale geocellular modelswere developed for both the blocks, RAD and REFB, based on structural inputs from the reservoirmapping of new 3D seismic data. The model has indicated upside potential of the field EUR of 255 MMstband was used for planning and drilling infill development wells, which were drilled during the 2006-2008period.In 2008, the 3D Geocellular Model was revised by integrating all geoscientific information from newlydrilled wells along with core data from RD-7. In this revision, stochastically inverted properties derivedfrom 3D OBC seismic data were used for the first time in the reservoir model to capture the reservoirdetails with a greater accuracy. The basic idea behind using inverted seismic data is to guide thedistribution of the reservoir parameters between the wells. The main subsurface uncertainties in building3D geocellular reservoir models are addressing structural and petrophysical uncertainty. Integrating thestochastically inverted reservoir characterisation in reservoir modeling approach leads to reducedvariance among the geo-statistical realisations and reduces overall uncertainty. As the model moreaccurately matches both well and seismic data, history matching can usually be achieved more quicklythan with traditional geostatistical based 3D models. The revised models show a further upside potentialof EUR of 278 MMstb from the field.The models were then upscaled for reservoir simulation studies. The history matched reservoir modelcould then be used to plan further development opportunities in the field.