A NEW WIRELINE TOOL FOR IN-SITU STRESS MEASUREMENTS

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.