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岩石热物性是研究盆地地热状态和构造—热演化过程的重要参数,也是盆地油气资源评价的重要研究内容之一。华南下扬子区是我国页岩气勘探开发的优选区块之一,页岩层系的热物性对于该区页岩气资源开发具有重要意义,但目前相关实测数据偏少,制约了对该区地温场及资源评价的认识。在18件泥页岩样品的热导率、生热率和密度等热物性参数测试的基础上,对下扬子区泥页岩的热物性进行了统计分析,并估算了整个扬子区的现今深部地层温度。研究表明,下扬子区泥页岩热导率大多数在1.500~3.000W/(m·K)之间,实测平均值为2.174±0.682W/(m·K);生热率大多数在1.00~2.50μW/m3之间,大部分集中于2.00~2.50μW/m3之间,实测平均值为2.04±0.86μW/m3。相比其他沉积岩类,页岩具有高生热率、低热导率的特殊热物性。样品间的热物性有相当大的变化,因此不能简单地以岩石的热物性作为区分岩石类型的指标。此外,扬子区的现今地温从东部的江浙皖(下扬子区)向西至上扬子区,表现为逐渐降低,但川东南地区和西南的楚雄盆地为高温区。下扬子区泥页岩的特殊热物性具有重要的地热涵义,这使得泥页岩类似保温盖层,其热屏蔽效应会导致页岩层及其下的地层温度升高,而页岩层之上的地层温度降低。这一特殊岩石热物性引起的温度异常势必改变深部地层的温度场分布,进而影响到烃源岩有机质热演化过程。研究区页岩气资源评价中必须考虑页岩的这一特殊的热物理性质。
Thermal physical properties of rocks are important parameters for studying the geothermal state and tectono-thermal evolution of the basin, and are also one of the important research contents of hydrocarbon evaluation in the basin. The Lower Yangtze region in South China is one of the preferred blocks for shale gas exploration and development in China. The thermophysical properties of shale beds are of great significance to the development of shale gas resources in this area. However, the current measured data is too small, which restricts the geothermal Field and resource assessment of awareness. Based on the testing of thermal properties, such as thermal conductivity, heat rate and density of 18 shale samples, the thermophysical properties of the shale in the Lower Yangtze region were statistically analyzed and the current depth of the Yangtze region was estimated Formation temperature. The results show that most of the shale thermal conductivity in the lower Yangtze area is between 1.500 ~ 3.000W / (m · K), and the average measured value is 2.174 ± 0.682W / (m · K) ~ 2.50μW / m3, most concentrated in 2.00 ~ 2.50μW / m3 between the measured average of 2.04 ± 0.86μW / m3. Compared with other sedimentary rocks, shale has a high heat rate, low thermal conductivity of the special thermal properties. The thermophysical properties of the samples vary considerably, and therefore the thermal properties of the rock can not simply be used as an indicator of the type of rock. In addition, the present geothermal temperature in the Yangtze region shows a gradual decrease from the eastern part of Jiangsu, Zhejiang and Anhui (the lower Yangtze region) to the upper Yangtze region, but the temperature in the Chuxiong Basin in southeastern Sichuan and the southwest is high. The special thermophysical properties of the shale in the Lower Yangtze region have important geothermal implications, which make mud shale similar to the thermal cap, whose thermal shielding effect causes the temperature of the shale layer and its subsurface to rise, while the formation above the shale layer Lower temperature. The abnormal temperature caused by the thermal properties of this particular rock will inevitably change the temperature field distribution in the deep strata and further affect the thermal evolution of organic matter in the source rock. The shale gas resource assessment must consider this particular thermophysical property of shale.