Real-time sensor data transmission for exploratory drilling

Problem

For geological investigations such as those required for tunnel construction, hydraulic tests are carried out in boreholes. To ensure a successful hydraulic in-situ test, it is necessary to measure the pressure at several points in the surrounding area of the probe in the borehole simultaneously and in real time.

Existing systems require one cable per reading, which is problematic due to the limited available radial space and the weight of the cables. In the developed system, three pressure readings and temperature can be transmitted to the surface in real time from depths of up to 1500 m via a single single-core armored coaxial cable with 3 mm diameter and 730 kg breaking strength (WirelineWorks 1-R-125-PD). The development is initially based on a student project and was subsequently supported by Innosuisse.

Challenges

Single cable for both sensor data transmission and remote power supply of the measuring unit in the borehole
Cable length up to 1500 m
Temperature in borehole up to 70 °C, humidity

Developed measuring system with data transmission from the borehole

Remote measuring unit for data acquisition and transmission with ST7580 powerline modem on up to 1500 m cable length
Energy-efficient remote power supply for operation up to 70 °C ambient temperature
Moisture protection
Surface unit and PC software for real-time display of measured values