| 热动力条件对白云凹陷深水区珠海组砂岩成岩演化过程的影响 |
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| 引用本文： | 李弛,罗静兰,胡海燕,陈淑慧,王代富,柳保军,马永坤,陈亮,李晓艳.热动力条件对白云凹陷深水区珠海组砂岩成岩演化过程的影响[J].地球科学,2019,44(2):572-587. |
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| 作者姓名： | 李弛 罗静兰 胡海燕 陈淑慧 王代富 柳保军 马永坤 陈亮 李晓艳 |
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| 作者单位： | 1.西北大学大陆动力学国家重点实验室, 陕西西安 710069 |
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| 基金项目： | 国家科技重大专项2016ZX05026003-005国家自然科学项目基金41572128 |
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| 摘 要： | 珠江口盆地白云凹陷位于中国南海北部,是目前我国深水油气勘探研究的重要区域.盆地现今大地热流值为24.2～121.0mW/m^2,单井现今地温梯度(Gra)最高可达6.64℃/100m,具"热盆"属性.白云凹陷裂后沉降阶段,特别是白云运动(23.8Ma)发生之后,盆地由断裂控盆转变为断裂、热作用共同控盆,热作用及热动力条件成为控制研究区储层成岩演化过程的重要因素,珠海组地层的镜质体反射率值、砂岩中次生流体包裹体均一温度、热液成因自生矿物等热流背景及岩石学记录为这一观点提供了有力证据.通过铸体薄片显微镜下观察与定量统计、电镜扫描观察、X-射线衍射分析等,发现白云凹陷北部中-低地温梯度(LGR,Gra≤4.5℃/100m)和南部高地温梯度(HGR,Gra>4.5℃/100m)两个地区珠海组砂岩的成岩作用特征、成岩演化过程存在以下差异:(1)中-低地温梯度地区珠海组砂岩的压实作用主要是静岩压实作用;高地温梯度地区珠海组砂岩的原生孔隙受静岩压实作用和热压实作用的共同控制,压实减孔速率高,等孔隙度埋深显著变浅;(2)地层升温速率的增大加快了储层中粘土矿物转化的速率,高地温梯度地区高岭石消失的埋深界限较中-低地温梯度地区浅,I/S(伊利石/蒙皂石混层)有序化进程较中-低地温梯度地区有所加快;(3)中-低地温梯度地区珠海组砂岩成岩演化过程属正常有序演变,高地温梯度地区受构造热事件的影响明显,深部流体参与了高地温梯度地区珠海组砂岩的成岩演化过程,地层孔隙水物质交换过程复杂,成岩演化进程加快,改变了碳酸盐矿物溶解-沉淀热平衡状态,各成岩作用过程活跃并出现一些典型的热液成因自生矿物组合.
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| 关 键 词： | 热动力条件 地温梯度 成岩演化 珠海组 深水砂岩 白云凹陷 珠江口盆地 |
| 收稿时间： | 2017-12-29 |
Thermodynamic Impact on Deepwater Sandstone Diagenetic Evolution of Zhuhai Formation in Baiyun Sag,Pearl River Mouth Basin |
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| Li Chi,Luo Jinglan,Hu Haiyan,Chen Shuhui,Wang Daifu,Liu Baojun,Ma Yongkun,Chen Liang,Li Xiaoyan.Thermodynamic Impact on Deepwater Sandstone Diagenetic Evolution of Zhuhai Formation in Baiyun Sag,Pearl River Mouth Basin[J].Earth Science-Journal of China University of Geosciences,2019,44(2):572-587. |
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| Authors: | Li Chi Luo Jinglan Hu Haiyan Chen Shuhui Wang Daifu Liu Baojun Ma Yongkun Chen Liang Li Xiaoyan |
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| Affiliation: | (State Key Laboratory far Continental Dynamics,Northwest University, Xi'an 710069, China;Shenzhen Branch of CNOOC Limited,Shenzhen 518067,China;Shaanxi Institute of International Trade & Commerce, Xianyang 712046,China;Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation,Chengdu 610091, China) |
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| Abstract: | Baiyun sag, located in Pearl River Mouth basin, South China Sea, is regarded as the major region for oil-gas research and exploration in deepwater area in China. The current heat flow of Pearl River Mouth basin is from 24.2 to 121.0 mW/m2, and the maximum geothermal gradient of single well is measured as 6.64℃/100 m, which proves that the basin is hot. The governing factor of the basin evolution was transformed from fault to fault-thermal collectively during the post-breakup subsidence stage, especially after the generation of the Baiyun movement (23.8 Ma). Since then, the thermal effect is known as one of the crucial elements in controlling the diagenetic evolution of the sedimentary strata in Baiyun sag, which is demonstrated by some petrological and heating records in sedimentary layer, such as the vitrinite reflectance, the homogenization temperatures of secondary fluid inclusions in sandstone and the authigenic minerals of hydrothermal genesis. Baiyun sag can be divided into low geothermal gradient region (LGR, Gra ≤ 4.5℃/100 m) and high geothermal gradient region(HGR, Gra>4.5℃/100 m). Analytical results of observation of casting thin sections, electron microscope scanning, and X-ray diffraction analysis, show the differences between these two regions in diagenetic processes of sandstone in Zhuhai Formation. (1) The compaction of sandstone in LGR is controlled mainly by lithostatic effect, while in HGR it is controlled by both thermal and lithostatic effect so that the isoporosity limit buried depth is more shallow than that in LGR. (2) The increase of heating rate accelerates the transformation progress of clay minerals in stratum, the depth that indicates the vanishment of the kaolinite in HGR is more shallow than that in LGR, and the ordering process of I/S (illite/smectite mixed layer) in HGR is more mature than that in LGR. (3) Deep-sourced fluid is involved in the diagenetic processes of sandstone in Zhuhai Formation in HGR, which is influenced by the tectonic heating event obviously, so that the thermal equilibrium of dissolution-precipitation of carbonate minerals is changed. The exchange process in interstitial water of the stratum is complex and active, and the authigenic hydrothermal minerals are produced in this process. |
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| Keywords: | thermodynamic condition geothermal gradient diagenetic evolution Zhuhai Formation deepwater sandstone Baiyun sag Pearl River Mouth basin |
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