石油学报

• 地质勘探 • 上一篇    下一篇

歧口凹陷滨海断裂带热流体活动及其对油气成藏的影响

龙华山1, 向才富2,3, 牛嘉玉1, 魏立春2,3   

  1. 1. 中国石油勘探开发研究院 北京 100083;
    2. 中国石油大学油气资源与探测国家重点实验室 北京 102249;
    3. 中国石油大学盆地与油藏研究中心 北京 102249
  • 收稿日期:2013-11-24 修回日期:2014-03-17 出版日期:2014-07-25 发布日期:2014-08-05
  • 通讯作者: 向才富,男,1975年2月生,1997年毕业于中国地质大学(武汉)资源勘查工程专业,2003年获中国地质大学矿产普查与勘探专业博士学位,现为中国石油大学(北京)地球科学学院副教授,主要从事地质流体及其成矿与成藏作用研究。Email:xcf@cup.edu.cn
  • 作者简介:龙华山,男,1985年6月生,2009年毕业于长江大学资源勘查工程专业,现为中国石油勘探开发研究院博士研究生,主要从事石油天然气地质综合研究。Email:longhsh@qq.com
  • 基金资助:

    国家重大科技专项(2011ZX05006-005、2011ZX05006-006)和自然科学基金项目(No.40872097、No.41272161)资助。

Hydrothermal fluid flow and its influence on the hydrocarbon migration and accumulation along Binhai fault in Qikou sag, Bohai Bay Basin

Long Huashan1, Xiang Caifu2,3, Niu Jiayu1, Wei Lichun2,3   

  1. 1. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;
    2. State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China;
    3. Basin and Reservoir Research Center, China University of Petroleum, Beijing 102249, China
  • Received:2013-11-24 Revised:2014-03-17 Online:2014-07-25 Published:2014-08-05

摘要:

热流体能够影响沉积盆地内物质组分的重新分配,如矿物的溶解和油气相态的变化,以及输导系统的热异常,通常沿断裂分布。滨海断裂带为控制烃源岩展布的断裂之一,同时也是流体热异常活动的场所。利用有机地球化学、流体包裹体、气体地球化学、成岩矿物及地层水化学特征等对研究区内流体的热活动进行了研究,为油气沿断裂发生运移和聚集提供了证据,进一步指明了油气勘探的有利方向。热流体沿断裂上涌发生热对流对局部温度场的改变体现在以下几个方面:1镜质体反射率异常反映局部烃源岩受局部温度场的变化发生热演化异常;2成岩期形成的流体包裹体均一温度大于其最大埋深时的温度;3黏土矿物出现同一深度段多类型和同一类型多层段的演化异常;4储层碎屑矿物颗粒的热蚀变。热流体对物质场的改变主要体现在以下几个方面:1热流体带来了深部幔源的无机CO2于浅层富集成藏;2大量高于卤水矿化度的深部流体渗入发生流体-岩石相互作用,导致储层中存在高矿化度的地层水;3储层早成岩期胶结于孔隙的碳酸盐类等矿物溶蚀形成多个次生孔隙带,进一步证实了水-岩相互作用,次生孔隙的发育来源于碳酸盐类矿物的溶解和重新分布,在一定程度上控制储层的物性;4热流体携带的大量物质发生流体-岩石相互作用导致靠近断裂带的岩石中所含微量元素异常。上述证据均指示了烃类流体能够沿断裂和渗透性砂岩储层发生运移,并可能聚集成藏形成大油气田。

关键词: 热流体活动, 热效应, 油气运移与聚集, 歧口凹陷, 渤海湾盆地

Abstract:

In sedimentary basin, hydrothermal fluid flow can affect the redistribution of materials (e.g., minerals dissolve in fluid and hydrocarbon dissolved in a basin) and the localized thermal anomaly along the pathway systems (most often faults). Binhai fault is one of the main boundary faults that controls the source rock distribution in Qikou sag, Bohai Bay Basin, which provides a space for flow anomalies of hydrothermal fluid. The investigation of hydrothermal fluid flow in Binhai fault bases on geochemical characteristics of organic materials, fluid inclusions, natural gases, diagenetic minerals, and formation water. Evidences for hydrocarbon migration and accumulation along the fault were obtained, with which a favorable direction for hydrocarbon exploration was pointed out. Hydrothermal fluid flow along the fault has created the abnormal high temperature field near the fault. Changes in local temperature field related to hydrothermal fluid upwelling along the fault were illustrated by the following evidences: (1) Abnormal vitrinite reflectance indicates abnormal thermal evolution of local source rocks; (2) Fluid inclusions with higher homogenization temperature than that formed at the maximal burial depth of the basin; (3) Clay minerals experienced abnormal evolution, with multi-types in the same depth segment and the same type in multi-segments; (4) Thermal alterations occurred in clastic mineral particles of the reservoirs. Changes in the material field caused by hydrothermal fluid flow were illustrated by the following evidences: (1)Inorganic CO2 originating from deep mantle and brought upward by hydrothermal fluid flow was enriched and accumulated in shallow; (2) Substantial high-salinity deep fluids penetrated and reacted with source rocks, leading to the accumulation of high-salinity formation water in reservoirs; (3) Multiple segments of secondary porosity zone were developed vertically, further demonstrating the occurrence of water-rock interactions. Secondary porosity zones were resulted from the dissolution and redistribution of carbonate minerals, which to some extent controlled the physical properties of reservoirs; (4) Water-rock interaction with substantial materials carried by thermal fluids led to abnormal enrichment of trace elements in rocks adjacent to the fault. Together the above evidences indicate that hydrothermal fluids migrated along the fault and permeable sandstone reservoirs in the study area, with great potential for oil-gas accumulation.

Key words: hydrothermal fluid flow, hydrothermal effect, hydrocarbon migration and accumulation, Qikou sag, Bohai Bay Basin

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