Micro-drilling technology

The Competence Center "Micro-drilling Technology" focuses on the development of the new drilling technology "Micro Turbine Drilling - MTD®". The fundamental motivation for MTD® comes from the field of deep drilling technology. MTD® is a mechanical drilling method for drilling sidetracks in the micro range—so-called Micro-Sidetracks (e.g., 2 inches or smaller) from an existing main borehole into the surrounding geology. Both soft sedimentary rocks and hard crystalline rocks (e.g., granite) can be drilled. It is a surgical and minimally invasive method, providing a low-risk and gentle alternative to hydraulic stimulation (fracking) without significant interventions in the geology.

How does the MTD® drilling technology work?

The main component of MTD® is a 1.5-inch micro-drilling turbine powered by pressurized water. Equipped with an innovative diamond drill bit, it is possible to drill various types of rock (e.g., granite, clay, sandstone) as well as steel in a single operation. When applied in a cased borehole, the drilling tool or drill bit does not need to be changed during or after the perforation of the steel casing, making it more time- and cost-efficient. To penetrate a formation with the Micro-Sidetracks, a deflection shoe is installed at the desired deflection point within the cased or uncased borehole using a deployment rod at the desired drilling depth. At this point, the kick-off direction for the Micro-Sidetrack can also be determined and set—if necessary. Subsequently, the micro-drilling turbine is run in on a flexible coiled tubing string up to the outlet of the deflection shoe, and the drilling process is initiated by pressurizing the turbine. The very compact design of the drilling tool allows for an exceptionally small deflection angle of the micro-drillings from the main borehole.

From a 5 1/2 inch casing, a Micro-Sidetrack with an approximate deflection angle of 50° can be drilled. With larger casing diameters, correspondingly larger deflection angles can be achieved; for casings of about 10 inches, a deflection angle of 90° to the main borehole is possible. Since the drilling tool is made of temperature-resistant components, MTD® can also be used at high temperatures. By drilling Micro-Sidetracks, the area around the borehole can be perforated, increasing the influx of geo-fluids into the borehole. This is particularly important for geothermal drilling, as it can enhance permeability in cases of insufficient productivity and reduce the risk of finding productive zones.

Field deployment in Haltern, Germany 2023

In another MTD® operation in Haltern in 2023, a total of 12 Micro-Sidetracks were drilled in two horizons (290 m and 330 m) using MTD® to connect the marlstone in the area for subsequent hydrotests to the borehole. Initially, a 5 ½-inch diameter steel casing had to be drilled through.

Field deployment in Bern, Switzerland 2024

In an operation in Bern, Switzerland, MTD® was used to enhance the efficiency of an underground thermal storage system. Up to 5 meters long Micro-Sidetracks were drilled from two main boreholes into the surrounding sandstone formation to better connect the storage rock to the main borehole. The Micro-Sidetracks were drilled in several horizons, reaching depths of up to 500 meters, from a 10 3/4-inch casing.