This paper describes the development of a wireline tool for open-hole
stress measurements. This tool includes a straddle packer module compr
ising surface controlled valves, pressure gauges, and a downhole pump.
Stress measurements are either based on the micro-hydraulic fracturin
g technique or the H.T.P.F technique (Hydraulic Tests on Pre-existing
Fracture). Before presenting the tool, we derive specifications for ob
taining reliable stress measurements. The maximum differential pressur
e (which is the interval pressure minus wellbore pressure) that the to
ol can currently sustain is 28 MPa (4000 psi) and flow rates of the or
der of 1 liter/min can be achieved. Results of field tests are describ
ed which demonstrate the high quality of the tool response.