Detailed Reservoir Characterization by Integrating Core, 3-D CT Scan and Borehole Imaging Datasets

Abstract

Computer Axial Tomography (CAT or CT scanning), is an X-ray based technique first developed in the late 1960s for medical imaging purposes. It has increasingly found applications in the earth sciences due to its ability to provide both quantitiative and qualititaive data regarding the internal structure of rocks and sediments, based on contrasts in density and chemical composition. The integration of 3D CT Scans from core with more traditional core description techniques, and other technologies such as borehole imaging (BHI), offers a powerful way of characterising sedimentological and structural features in a reservoir. With BHI it is possible to identify and orient geologic features over relatively long well sections (100s - 1000s of feet). However, BHI resolution is still relatively low compared to what can be observed in core, which offers very detailed insights in to the reservoir rock, but often over much shorter intervals (100s of feet at most). Despite its advantages, in slabbed core subtle features can still be difficult to see with the naked eye, especially if it is oil stained. In these cases the use of 3D CT scans offers a very high resolution image of the rock that can be used to enhance the reservoir characterisation. This study presents detailed sedimentological and structural interpretations from a deepwater turbidite reservoir, generated by integrating 3D CT scans, BHI and core-based observations. Firstly, the 3D CT scans allow more detailed recognition of sedimentary facies; commonly sandstones that seem structureless in the slabbed core are shown to be space-laminated or dewatered in the CT scans. Secondly, by using bedding features common to both the BHI and core data sets, it is possible to orient the 3D CT scans and demonstrate that interpreted fractures in the BHI correspond to deformation band sets in the core. More deformation bands are identified in the 3D CT scans than with the BHI. However, the vast majority of the fractures interpreted from the BHI match both in location and orientation those identified in the CT scans. This study therefore demonstrates that by combining core, 3D CT scans and BHI it is possible to fully orient both sedimentological and structural features in order present a more complete picture of the reservoir at a particular well location, and provide detailed calibration for wells where only BHI are available.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017