ENGINE Exploration tools

Activities

In situ stress testing

Based on earlier work at the University of Minnesota and at the Ruhr-University Bochum, MeSy has developed the Wireline Hydrofrac technique, where the double-straddle packer sonde is moved within the borehole on a standard logging cable. This allows on-line downhole pressure recording. The hydraulic pressure line consisting of stainless steel tubing provides an extremely stiff hydraulic system. The system has been used in several deep boreholes to 4 km depth as well as in numerous shallow geotechnical drillholes. At high temperature aluminum packers are being used which can easily be removed by drilling.

Packer Development

Inflatable packers to seal-off specific test sections in boreholes generally consist of reinforced rubber elements not suited for high temperatures. Therefore, MeSy has developed aluminum packers which can be inflated at pressures of about 20 MPa and provide seals for pressures up to 100 MPa. The soft aluminum shells remain in the borehole, while the intelligent stainless steel internal parts can be withdrawn by the wireline logging cable. Similar metallic packers have bee developed as casing packers for the Soultz HDR project or for nuclear waste storage projects to permanently seal boreholes.

Equipment

• wireline logging winch MKW 5000 with 6000 m high temperature 7-conductor logging cable type Rochester (container-mounted);

• wireline logging winches MKW 1600 with 2000 m 7-conductor logging cable type Rochester (trailer-mounted), including tripod;

• wireline logging winches MKW 1000 and MKW 500 with 1000 and 500 m 7-conductor logging cable type Rochester (frame mounted for easy air freight transport), including tripod;

• straddle packer sondes type PERFRAC with reinforced rubber packers for boreholes of diameters ranging from 60 mm to 300 mm;

• high-pressure pump capacities consisting of frequency-controlled pumps for pressures up to 40 MPa and flow-rates up to 3 liters per second;

• several thousand meters of stainless steel coil tubing of OD/ID 10/8 mm;

• pressure, temperature and flow-rate sensors;

(data acquisition)

• multi-channel data acquisition system type SILVI (16 bit, < 10 Hz)

• multi-channel data acquisition system type DELPHIN (24 bit, < 10 Hz)

Software

• MeSy codes SESAM or GENSIM for the analysis of hydrofracturing pressure and fracture orientation data to derive in-situ principal stresses;