摘要
盆地热体制及深部温度估算对油气和区域地热能资源评估具有重要意义。南方上扬子区是海相油气勘探的重要区块,近年来更是我国页岩气勘探的主要选区。然而,由于数据不足及研究目标的分散,该区的盆地热体制特征还有待深化。结合前人已有地热数据,并整合新近开展的稳态测温数据,我们揭示了上扬子区现今地温梯度、大地热流分布特征,继而估算了1000~6000m埋深处的深部地层温度和2套主要古生界海相烃源岩底界面处的温度。结果表明,上扬子区具有中-低温的地热状态,其现今地温梯度和大地热流的范围(平均值)分别为10~74℃/km(24℃/km)和27~118mW/m^2(64mW/m^2),整体上从东北向西南方向递增,呈现出"东北低、西南高"的分布趋势。1000~6000m埋深处估算温度的分布格局与地温梯度及热流的分布趋势基本一致。东北部的鄂西-湘北地区为低温区,中部的四川盆地其大部分为中温区,西南的云南地区为高温区。上扬子区现今地热分布格局受区域差异构造和岩浆作用控制。结合储层温度估算并综合其他油气地质资料,提出川东的石柱-涪陵、川南的威远-自贡-泸州和宜宾-长宁等区的下志留统龙马溪组页岩层系是上扬子区油气勘探有利区带。
A characterization of the geothermal regime of sedimentary basins and associated subsurface formation temperature is crucial for the assessment of hydrocarbon generation,preservation,and estimation of regional geothermal energy potential.The Upper Yangtze area of the South China is one of the long-lasting regions for marine oil and gas exploration.Recently,it is the emerging area for shale gas exploration in China.The accurate characterization of the thermal regime in this area could constrain potential assessment of shale gas.However,further investigation is needed given the poor data coverage and associated inconsistency of previous studies.In this study we have combined the measured rock thermal properties and newly acquired steady-state temperature logging data with drill stem test temperature data to determine the present-day geothermal gradient and heat flow pattern,and estimate the subsurface formation temperatures-at-depth in the range of 1000〜6000 m in the upper Yangtze area,along with temperatures at the bottom surfaces of two major Paleozoic marine source rocks in the Sichuan Basin.our results demonstrate that this area has a moderate-low geothermal regime,and its present-day geothermal gradient and heat flow range(mean value)are 10〜74 C/km(24 C/km)and 27〜118mW/m2(64mW/m2)respectively.Regional heat flow and temperature increase from the northeast to the southwest,showing a trend of"low in the northeast and high in the southwest".In the northeast,the west of Hubei and the north of Hunan province are characterized by low temperature areas;in the middle,the majority of the Sichuan Basin shows a moderate temperature;in the southwest,the Yunnan Province shows high temperature.This spatial variability of geothermal pattern in this area is mainly controlled by differential tectonics and magma activities.On the basis of predicted reservoir temperature and other geological and geochemical conditions,we propose that the shale system of the Lower Silurian Longmaxi Formation in Shizhu-Fuling,Weiyuan-Zigong-Luzhou and Yibin-Changning are likely to be the most favourable areas for shale gas exploration in this region.
作者
李香兰
刘绍文
徐明
李旭东
郝春艳
LI Xianglan;LIU Shaowen;XU Ming;LI Xudong;HAO Chunyan(School of Geographic and Oceanographic Sciences,Nanjing,210023;Key Laboratory of Ministry of Education for Coast and Island Development,Nanjing University,Nanjing,210023;Tianjin Geothermal Exploration Development Designing Institute,Tianjin,300250)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2020年第6期1896-1910,共15页
Acta Geologica Sinica
基金
国家科技重大油气专项专题(2017ZX05008-001)
国家重点研发计划项目课题(2017YFC060140006)联合资助的成果。
关键词
地温梯度
热流
地层温度
页岩气
四川盆地
上扬子区
geothermal gradient
heat flow
formation temperature
shale gas
Sichuan Basin
Upper Yangtze area
