Geothermal measurements in the pilot-boreholes of the China Continental Scientific Drilling

The geothermal measurements in the pilot-boreholes of the China Continental Scientific Drilling (CCSD) indicate that the temperature gradients in the target area of the deep drilling range from 19 to 26 degreesC/km, which is lower than that (25-30 degreesC/km) for the global continental area and sim ilar to that for the KTB (21-28 degreesC/km). Thermal conductivity measurem ents for 44 core samples show that the ultra-high pressure (UHF) metamorphi c rocks have 50% higher thermal conductivity (with a mean of 3.94 +/- 1.26 W/mK) than that for the average value of the upper crust. The measured heat flow values vary between 76 and 80 mW/m(2), higher than that for the globa l continental area (65 +/- 1.6 mW/m(2)) and the continental China (61 +/- 1 5.5 mW/m(2)) as well as the adjacent North Jiangsu Basin (68 mW/m(2)), but lower than that below 1000 in in the KTB (85 mW/m(2)). The elevated heat fl ow in the pilot-boreholes can be attributed to the lateral heat concentrati on due to higher rock thermal conductivity of the UHP belt than that of the adjacent rocks. Lower deep temperature in the target area of the deep dril ling can be expected due to the lower measured temperature gradient, which means that the Sulu area is geothermally suitable for continental deep dril ling.