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Geological Model Review During The Intense Infill Drilling
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, ECMOR XVI - 16th European Conference on the Mathematics of Oil Recovery, Sep 2018, Volume 2018, p.1 - 9
Abstract
The main task is to review and adjust geological model during the process of intense infill drilling in oil field Velebit and to identify zones with residual reserves, define current oil-water (OWC) and oil-gas (OGC) contact and to achieve higher accuracy of production forecast of new wells. Infill drilling started in 2013 as a result of geological and reservoir engineering study and it was carried out in 3 stages: first stage (from 2013 to 2015)-13 wells, second stage (in 2016)-28 wells and third stage (in 2017)-27 wells were drilled.
The object of interest is an oil field with a gas cap Velebit located in norther part of Serbia. The field was discovered in 1963 and in terms of production, it is one of the most important fields in Serbia. The reservoir is located in Lower Pontian and Middle Trias. Lithological deposits of Lower Pontian are represented by sands, sandstones (Pt1-2) and conglomerates and shaly sandstones (Pt1-1). Middle Trias (T1) is represented by dolomitic limestones and dolomites.
As the drilling went on new information kept coming and the geological model underwent changes. Drilling out of the South and West part of the field revealed the deeper current OWC then initially expected. Drilling out of the East part of the field revealed a tilted OWC. Results of analysis showed a link between the current OWC, structural factor and overall formation thickness.
Results of the undertaken research include adjustment of geological model, monitoring current OWC and OGC, identification of zones with residual reserves for future infill drilling, recommendation for new wells location in respect for tilted and current OWC, identify perspective zones near OGC and reducing risks associated with drilling plans.