Print this pageReduced Uncertainties in Geosteering and Well Placement in Carbonate Reservoirs Through Better Understanding of the Facies and Sedimentology in Real-Time
Experience to date shows that the drilling environment offers a good platform for high definition electrical borehole imaging. At the time of drilling, invasion and borehole wall rugosity are often minimal and electrical images generated by sensors that rotate with the drill string provide a full coverage of the borehole. It also provides an opportunity for real-time geological analysis while drilling and the decision making that is unavailable with wireline. Detailed analysis of images reveals discrete sedimentological and textural features aiding facies recognition in carbonate reservoirs. These facies can be up-scaled to facies associations and eventually used for depositional environment interpretation. This leads to wider prospect delineation and confirmation of the local geological model. The study also demonstrates the strength of early geological information in high-resolution for reducing geological uncertainty at an early stage in the development drilling programme.
We show case studies from several carbonate reservoirs in which high resolution electrical images have been acquired in conjunction with geosteering. From post well analysis, we can define the key criteria that help in recognition of reservoir position; correlatable sedimentary surfaces and image facies/patterns. We test the distribution of facies and sedimentological features that can be recognised in horizontal boreholes by comparison to vertical offset wells, in addition to automated facies recognition from image log responses.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil