Q218: Slim hole drilling including TTRD, coiled tubing drilling and advances in expandable and multilateral technology
Thursday 14th & Friday 15th June 2018, hosted by Premier Oil – Aberdeen, Scotland)
Slim hole drilling was developed to reduce well cost and provide re-entry opportunities to exploit reservoir targets near an existing wellbore. Today’s financial pressures make the claimed reduction in cost attractive in the concept stage. In the 90s the technology became available to drill smaller and smaller boreholes, but in the last decade the uptake appeared to have halted in many regions in the world. This means there are still technological challenges to overcome.
Slim hole drilling means different things to different people, but in this context we refer to it as drilling boreholes smaller than 8.5in diameter. The concept reaches further than the size of the hole alone. Accessing the near field targets from existing wellbores requires side-tracking from the original borehole, which opens the door to additional technologies that have an impact on the overall well concept. For example, multilateral junction technology would need to be fit-for-purpose and meet production requirements, which could drive the feasibility. The use of Coiled Tubing could be an opportunity to avoid allocating rig time, if the reservoir targets are within reach.
Exiting an existing wellbore could also require downsizing the well design from the motherbore’s original design, often leading to unconventional casing and hole sizes. To keep a contingency casing option available it might be required to consider expandable technology. In line with this concept expandable liners can be combined to create a monobore well design, without reduction in hole size at each casing point, potentially allowing an significant extension of the well. What can we expect from this technology in the future?
Knowing the current and future technological capabilities and understanding the risks and challenges that still need to be overcome will allow effective application of slim hole drilling and applying expandable technologies.