Integrated approach to identify fault pattern and fracture corridors in a matured field
Authors: Thakur, R.K., Wani, M.R., Choudhary, M.A., Al-Rashidi, H. and Al-Hajeri, M.
Journal: Society of Petroleum Engineers - EUROPEC/EAGE Conference and Exhibition 2009
ISBN: 9781613994276
Abstract:The development of low reservoir pressure pockets and deteriorating reservoir properties in southern parts of the Ratawi Oolite reservoir has revealed the complex nature of fault and fracture network in Wafra field. These faults could not be observed directly on 3D seismic data due to the lack of perceptible change in seismic trace along stratigraphic boundary. This problem has been resolved with innovative fault/fracture characterization technique synthesizing seismic attributes, well information and reservoir behaviour. The instantaneous phase attribute volume derived from reprocessed 3D seismic data highlighted the lateral impedance contrast to provide better resolution at discontinuities to detect even subtle change in dip and azimuth to identify fault traces along seismic sections. The alignment of fault pattern was mapped with variance cube, sum of amplitude and edge detection attributes along Ratawi Oolite Top seismic reflector. The localized nature of the effect of injection wells to improve reservoir pressure in the Ratawi Oolite reservoir in the southern portion of the field has stressed upon the presence of fault compartments and fracture corridors in the vicinity of these drilled wells. The envisaged fracture corridors were mapped integrating seismic attributes such as coherency, attenuation time with interpretation of rose diagram, Formation Micro Image and core data. The heterogeneity in reservoir behaviour, complex nature of fault and associated fracture network was further confirmed by impedance slice at Ratawi Oolite level derived using post stack seismic inversion technique. The estimated depth map with fault and fracture corridors at the Top Ratawi Oolite reservoir, generated using interpreted seismic time, modelled stacking velocity provided a guide to plan development and delineation wells in this field. This paper presents an integrated approach to identify alignment of fault and fracture corridors to plan for optimum location of injectors/development wells to optimize recovery in a matured field.
Source: Scopus