四川盆地钻孔温度测量及现今地热特征

Borehole temperature logging and characteristics of subsurface temperature in the Sichuan Basin

基于四川盆地9口钻孔的稳态测温资料和297块岩石样品的热导率数据,报道了9个高质量的大地热流数据,提出了沉积地层岩石热导率系列柱.结合前人的数据资料,绘制了地温梯度和大地热流等值线图.四川盆地沉积地层的岩石热导率变化主要由岩性控制,与现今埋藏深度没有明显的相关性.盆地的地温梯度为17.7～33.3℃/km,平均值为22.8℃/km.盆地的大地热流为35.4～68.8 mW/m^2,平均值为53.2 mW/m^2,具有典型克拉通型盆地中低热流特征.在区域分布上,大地热流明显受基地构造控制,表现为川中及川西南地区较高,川北地区较低.

Based on temperature logging of 9 boreholes and thermal conductivity measurements of 297 samples from the Sichuan Basin, 9 highly qualified terrestrial heat-flows are reported. Combining published data, contour maps of geothermal gradient and heat flow are presented. The results show that variations of thermal conductivity of sedimentary rocks in the Sichuan Basin are mainly controlled by lithology, rather than current burial depth. Present-day geothermal gradient in the basin ranges from 17.7 to 33.3 ~C/kin with a average of 22.8 ~C/km and the heat flow from 35. 4 to 68. 8 mW/m^2 with a average of 53. 2 mW/m^2. These results suggest that the thermal state of the Sichuan Basin is similar with other craton basins, which are characterized by middle-low heat flow values. In regard to the lateral heat flow distribution in the Sichuan Basin, it is shown, at first order level, that relatively higher values occur in the central and southwest parts where basement is relatively shallower, while relatively lower values in areas with deeper basement burial. Therefore, it is Sichuan Basin is mainly dependent suggested that the lateral variations of the heat flow in the upon basement structures.