南海北部陆缘琼东南盆地深水区现今地热特征  

Geothermal Regime of the Deep Area of the Qiongdongnan Basin,Northern Continental Margin of the South China Sea

作　　者：吴迪[1] 李香兰[1] 刘绍文[1,2] 朱继田 李旭东 熊小峰[3] 尹宏伟 WU Di;LI Xianglan;LIU Shaowen;ZHU Jitian;LI Xudong;XIONG Xiaofeng;YIN Hongwei(Key Laboratory of Coast and Island Development of the Ministry of Education,School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;Collaborative Innovation Center for the South China Sea Studies,Nanjing 210093,China;CNOOC(China)Zhanjiang Branch,Zhanjiang 524057,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学海岸与海岛开发教育部重点实验室,地理与海洋科学学院,南京210023 [2]中国南海研究协同创新中心,南京210093 [3]中海石油(中国)有限公司湛江分公司,南海西部石油研究院,湛江524057 [4]南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2022年第6期933-942,共10页Geological Journal of China Universities

基　　金：国家油气重大科技专项子课题“琼东南盆地深水区构造差异化及构造动力学成因机制”(2016ZX05026-002-007);国家自然科学基金(4207020139);中国石油科技创新基金研究项目(2020D-5007-0104)联合资助。

摘　　要：沉积盆地热体制信息的准确获取对盆地成因演化动力学研究和油气资源评价和勘探开发具有重要的意义。琼东南盆地作为南海北部深水油气勘探开发的重点地区,已陆续获得重大突破,但其深水区的热状态特征还不甚明了。结合该区21口新钻井的地层测温数据和岩石热物性参数,文章揭示了琼东南盆地现今地热特征。研究表明,该区平均热流值为73.2±8.67 mW/m^(2),平均地温梯度值为39.4±4.86℃/km,整体属于“热盆”。盆地的热流和地温梯度在平面分布格局上均呈现出“浅低深高”的趋势,其中,深水区的平均热流值要比浅水区高出16 mW/m^(2),其平均地温梯度值也要高出10℃/km,这一差异与岩石圈差异拉张减薄以及沉积物热披覆效应等因素有关。此外,研究表明盆地东部的长昌凹陷为热流高值异常区(>90 mW/m^(2)),其高热流背景与晚中新世以来的岩浆侵入和断裂活动等有关。上述成果为盆地深水区油气资源潜力评价提供了新的地热学参数和科学依据。The accurate knowledge of geothermal regime of sedimentary basins holds importance for investigating basin formation dynamics and hydrocarbon potential assessment as well.The Qiongdongnan Basin is a key area of deep-water hydrocarbon exploration and development in the northern South China Sea,but the geothermal regime of the deep water area in the basin is still open.Combined the corrections of formation temperature data of 21 new drilling wells with measured rock thermal properties,the basic characteristics of the present-day geothermal field in the Qiongdongnan Basin were presented here.Our results show that the heat flow data in the study area are mainly concentrated in the range of 60-90 mW/m^(2),with the mean of 73.2±8.67 mW/m^(2).Most of the geothermal gradients in the study area are concentrated in 30-50℃/km,with an average of 39.4±4.86℃/km.In addition,both the heat flow and the geothermal gradient show the similar trend and featured by higher in deep-water area and lower in the shallow water area.The average heat flow of the deep-water area is 16 mW/m2 higher than that in the shallow water area.The average geothermal gradient for the deep-water area is 10℃/km higher than that in shallow water.This is mainly due to the differential extension and thinning of the lithosphere and thermal blanketing effects of the sediments.In addition,there is an anomaly high heat flow zone in the Changchang sag,with the mean of 94.5±6.4 mW/m^(2),which is the results of Late-Miocene magmatic intrusion and fracture activities.The results mentioned could provide new geothermal parameters for basin modeling and hydrocarbon potential assessment of the Qiongdongnan Basin.

关 键 词：大地热流 地温梯度 热体制 琼东南盆地 

分 类 号：TE122.14[石油与天然气工程—油气勘探]