High-Quality Electrical Borehole Images While Drilling: Increased Confidence in Well Positioning and Drilling-Hazard Mitigation From Real-Time Data

摘要

Recent developments in technology have lead to the ability to acquire and transmit high resolution electrical borehole images while-drilling. The advantage of imaging while drilling is to acquire data with minimal rugosity of the borehole wall and before appreciable invasion of the drilling fluid in order to obtain the best possible quality images. High quality, real-time images and the resulting ability to proactively steer the drill bit provide benefits to both the driller and geologist through the ability to make real-time decisions on optimum well placement. Further implications for the driller are reduction in NPT through drilling hazard mitigation and maintaining borehole stability because of the immediate identification of breakout. For the geologist, the real-time interpretation of structural and sedimentary information from electrical images can be used to steer the drill bit in order to: 1. Stay inside a desired sedimentary package based on the rapid interpretation of sedimentological criteria (e.g. sedimentary steering by using predictive models of sandbody geometry and internal architecture), 2. Give fore-warning of approaching features in the proposed drill path (e.g. fracture intensity increasing towards a fault zone), and 3. Avoid or mitigate adverse features that may have a negative impact on production (e.g. avoiding reservoir roof rocks by steering away in advance). Field tests have shown the ability to transmit to surface real-time compressed images that can be optimized for deriving structural information whilst higher resolution images can be used for sedimentary analysis. This paper shows how these developments can be used to increase confidence in well placement, at the same time as avoiding drilling hazards.