| Title | Technology Roadmap for Geothermal Hard Rock Drilling |
|---|---|
| Authors | Randeberg, E; Kragset, S; Lohne, H P; Arild, Ø |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Geothermal drilling, hard rock |
| Abstract | The development of more efficient hard rock drilling technologies will be valuable for the geothermal, oil and gas and mining industries. Low penetration rates, equipment wear and damage are challenges often associated with the destruction of hard rock. This paper investigates the hard rock drilling process and includes a state of the art review of the drilling technologies that attempt to address the challenges. Drilling can be broken down into three fundamental processes that need to be addressed to achieve efficient hard rock penetration: 1) Transfer of mechanical energy to the rock, thereby breaking or fracturing it 2) Keeping secondary effects of the impact within tolerable limits (e.g. bit wear, detrimental drill-string dynamics) 3) Sufficient removal of cuttings from the bit/rock interface Deep drilling poses a particular challenge for the control of the rock breaking process in view of the great distances involved coupled with geological uncertainty and harsh environments (e.g. high temperature). Effective management of the drilling operation is complicated by the lack of real-time information at a sufficiently high bandwidth, meaning that precise process control is difficult. A number of surveillance systems and models are used to attempt to mitigate the lack of down-hole information. The current best practice regarding rock breaking and the avoidance of dysfunctional behaviour is presented. Drilling tools must be constructed to achieve optimal rock breaking performance. However, tools also need to resist excessive wear and failure, and broken rock must be effectively removed from the bit/rock interface. A discussion is given of recent downhole tool developments and aspects of the drilling fluid and circulation systems. 1 https://nextdrill.wordpress.com/ Hard rock drilling improvements are discussed in terms of three technology areas: 1) Improved process control 2) Better tools and solutions 3) New drilling systems In accordance with this approach, a roadmap is suggested for technologies that seem to have the greatest potential. |