华南下扬子区现今地温场特征

Present geothermal regime of the Lower Yangtze area,South China

在前人研究成果的基础上,整合了新近获取的地温数据,基于下扬子区66口钻井的试油温度数据及岩石热物性参数资料,分析了该区现今地温梯度、大地热流及1 000~5 000 m埋深处的地层温度的分布特征。研究表明：该区大部分的现今地温梯度为18~25℃/km,其中,苏北盆地地温梯度较高（平均为30℃/km）;全区现今大地热流为48~80 mW/m2,平均为60 mW/m2,与全球大陆区平均热流相当。深部地层温度估算指出,该区北部4 000 m埋深处的温度已达150℃,区内主要古生界海相烃源岩层系目前为高-过成熟的生气阶段,具有适宜页岩气保存的温度条件。

Authors combined the previous data and newly collected geothermal data,including temperature and rock thermal properties,to obtain present geothermal gradient,subsurface formation temperature at the depths of 1 000-5 000 m and the heat flow in the region.The results show that the present geothermal gradient of the Lower Yangtze area is 18-25 ℃/km,while that of the Subei Basin is as high as 30 ℃/km,and the heat flow ranges from 48 mW/m2 to 80 mW/m2 with a mean of 60 mW/m2,approximating to that of the global continental areas.The prediction of deep subsurface formation temperature indicates that the formation temperature of the northern area is larger than 150 ℃ at 4 000 m depth,and the main Paleozoic marine hydrocarbon rocks are within high-over mature regime and the gas generation stage,suggesting this area is of suitable temperature condition for shale gas preservation.