中国大陆科学钻探靶区深部温度预测

依据中国大陆科学钻探(CCSD)两口先导孔中地热测量和岩石样品热物性参数,对5000m深钻的可能钻遇温度进行了预测.先导孔中地温梯度介于1-26℃/km;岩石热导率变化为2.64-8.81W/(m@K),平均(3.4±1.26)W/(m@K);实测热流值为76-80mW/m2;30块岩石样品放射性生热率变化为(0.0-2.17)μW/m3,450m深度以上层平均(0.76±0.5)μW/m3,以下层段平均(0.48±0.2)μW/m3,生热率随深度递减,但变化趋势难以明确判定.分别对热流和热导率取上、下限,采用不同的生热率随深度的分布函数,区分考虑或不考虑热导率的温度相关性,分别计算出5000m深度内可能的温度分布剖面.计算结果表明,超深井于5000m垂直深度上的温度将达到110-140℃,2000m深度的探井钻遇温度将介于54-64℃.此外,考虑热导率的温度效应后预测的温度一般高于未考虑热导率温度效应5-8℃.

PREDICATION OF THE DEEP TEMPERATURE IN THE TARGET AREA OF THE CHINA CONTINENTAL SCIENTIFIC DRHLING

The deep temperatures for the main borehole（5000m） of the China Continental Scientific Drilling （CCSD） are predicatd based on the geothermal measurements and thermal properties of the core samples from two pilot boreholes. The temperature gradient for the pre pilot boreholes ranges from 19 to 26℃/km; and the thermal conductivity varies between 2.648.81W/（m·K） with a mean of 3.94±1.26W/（m·K）; the measured heat flow values vary between 76 and 80mW/m 2;radiogenic heat production for 30 core samples ranges from 0.09 to 2.17μW/m 3,with a mean of 0.76± 0.5μW/m 3 for the section above 450m and 0.48±0.2μW/m 3 for the lower section. The heat production shows a decrease with depth but no trend can be well defined. Possible temperature profiles are calculated with the upper and the lower limits that are designed according to the measured heat flow and thermal conductivity values,and for different distribution of heat production as well as for the temperature dependant thermal conductivity or not. The results of predication indicate that the 5000m main borehole will reach a temperature range of 110140℃ at the bottom and 5464℃ at the depth of 2000m. In addition,the predicted temperature will be 58℃ higher if one taking into account of the temperature dependance of thermal conductivity.