石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (4): 738-751.doi: 10.11743/ogg20190405

• 油气地质 • 上一篇    下一篇

喜马拉雅中晚期断弯褶皱-大气水岩溶储集体形成——以塔里木盆地西北缘柯坪-羊吉坎大湾沟组碳酸盐岩为例

钱一雄1, 田蜜1, 李慧莉2, 陈跃1, 沙旭光3, 李洪泉3   

  1. 1. 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214151;
    2. 中国石化 石油勘探开发研究院, 北京 100083;
    3. 中国石化 西北油田分公司 石油勘探开发研究院, 新疆 乌鲁木齐 830011
  • 收稿日期:2018-01-15 修回日期:2018-11-08 出版日期:2019-08-28 发布日期:2019-06-01
  • 作者简介:钱一雄(1962-),男,博士、教授级高级工程师,碳酸盐岩沉积与储层。E-mail:qyx9167@vip.sina.com。
  • 基金资助:
    国家重点研发计划专项(2017YFC0603103);石油化工联合基金项目(U1663209);国家科技重大专项(2011ZX05005-0023)。

Formation of fault bend fold-controlled meteoric karst reservoir in the middle and late Himalayan movement: A case study of the Dawangou Formation carbonate rocks at Yangjikan section, Keping, northwestern Tarim Basin

Qian Yixiong1, Tian Mi1, Li Huili2, Chen Yue1, Sha Xuguang3, Li Hongquan3   

  1. 1. Wuxi Research Institute of Petroleum Geology, Petroleum Exploration and Production Research Institute, SINOPEC, Wuxi, Jiangsu 214151, China;
    2. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China;
    3. Research Institute of Exploration and Development of Northwest Oilfield Branch Company, SINOPEC, Urumqi, Xinjiang 830011, China
  • Received:2018-01-15 Revised:2018-11-08 Online:2019-08-28 Published:2019-06-01

摘要: 在新疆柯坪羊吉坎中奥陶统大湾沟组碳酸盐岩岩溶特征刻画的基础上,采用了岩相学、地球化学以及褶皱脱空分析等综合研究,并结合了古气候分析等溶蚀实验结果,揭示了喜马拉雅中晚期受断弯褶皱抬升及大气水溶蚀控制岩溶作用过程;估算了受构造挤压的层间滑脱以及溶蚀作用所产生孔隙大小。褶皱脱空(VSD模拟计算)可产生0.2%~0.5%孔隙发育带,占目前有效空洞率的1/50~1/100,但前者为“达西流及溶蚀作用”起了重要的作用。羊吉坎岩溶剖面中发育了机械破碎-流水充填物(角砾岩)、钙华及巨晶方解石;与大湾沟组的围岩相比,其δ13C(PDB),δ18O(PDB)偏负明显、两者呈线性关系,缝洞中方解石中发育了单相盐水溶液包裹体,典型的大气水岩溶标志;由下而上连续钙华沉积δ13C(PDB),δ18O(PDB),δ34S(V-CDT)偏负的程度减弱;从钙华、巨粗晶至(长)柱面的偏三角面体的方解石中,Al2O3,Fe2O3,MgO,K2O,Na2O含量依次降低;反映了半潮湿-潮湿至半潮湿-干旱气候条件及其水动力的变化。进一步推断,在潮湿气候和强水动力条件下,高1.5~2.0 m的溶洞体最短可在5 ka内形成,而相对干旱期需要较长的时间。

关键词: 褶皱脱空(VSD), 地球化学, 岩溶, 碳酸盐岩, 大湾沟组, 喜马拉雅中晚期, 柯坪-羊吉坎, 塔里木盆地

Abstract: The karst profile at Yangjikan section, Keping, northwestern Tarim Basin, provides an excellent opportunity to evaluate the relative importance of reaction between fault bend fold-controlled uplift and meteoric water dissolution-controlled karstification during the middle and late Himalayan movement; and then the porosity caused by interlayer decollement under structural compression and dissolution was estimated, in line with the comprehensive study of petrographic, geochemical and fold disengaging analyses.The fold disengaging(simulated with VSD)facilitated the result of 0.2%-0.5% porous zones, accounting for 1/50-1/100 of the effective and actual empty-cavity rate.However, the porous zones have played a significant role in Darcy flow channel formation and karstification.The breccias related to mechanical fracture filling, calcareous tufas and megacrystalline calcites are well developed in the Yangjikan section karst reservoir.Compared to the surrounding rocks of the Dawangou Formation, the negative and linear correlation of δ18O(PDB)and δ13C(PDB)in the formation is distinct, and single-phase aqueous inclusions, typical products of meteoric water karstification, grew in the megacryst calcites within fractures and cavities.A successive tufa depositions from the lower to the upper section of karst profile, are characteristic of weakening negative depleted δ13O(PDB), δ18O(PDB) and δ34S(V-CDT).The content of Al2O3, Fe2O3, MgO, K2O, and Na2O decreases from tufas to megacrystalline calcites to(long)cylindrical scalenohedron calcites, indicating a transition in climate conditions from semi-wet to humid, to semi-humid and then to drought, as well as changes of hydrodynamic conditions.Moreover, the karst cavern of 1.5m-2.0m high can be formed within less than 5ka under a hot humid and strong hydrodynamic condition, while it may take a longer time in semi-humid and drought climate.

Key words: fold disengaging(VSD), geochemistry, karst, carbonate rock, Dawangou Formation, Middle and Late Himalayan movement, Keping-Yangjikan, Tarim Basin

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