Research on the memory SRO telemetering system used for drill stem testing

It is very important to obtain accurately downhole temperature and pressure in oil and gas well testing. A memory surface read-out (SRO) telemetering system used for drill stem testing, which is based on coreless electromagnetic coupling principle and may be applied to downhole adverse circumstances in cooperation with full bore drill stem testing apparatus, is proposed in the paper through contrasting different oil and gas well testing methods at present. The SRO pressure gauge and memory gauge might be alternately controlled, and the parameters above and below valve could be accurately measured in real-time by the sys tern. By means of the remote transmission of modulation energy signals of downhole data along the cable, the SRO might be realized; and the methods of calculating actual pressure and temperature values were put forward in combination with sensor characteristics. The experimental results indicated that the coreless electromagnetic coupling could function normally under the shielding of casing; and this system might continuously work for more than 240 h at downhole temperature of 125°C and pressure of 70 MPa. It has been successfully applied to the onshore well testing.