靖边潜台南部奥陶系马家沟组古岩溶储层地球化学特征
Geochemical characteristics of a paleokarst-reservoir in Ordovician Majiagou formation in southern Jingbian tableland
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摘要: 鄂尔多斯盆地奥陶系马家沟组由于受加里东运动影响而隆起抬升遭受风化,其顶部形成了良好的岩溶油气储层。本文通过对可溶岩的溶蚀孔充填物、角砾间的胶结物和碳酸盐原岩进行δ13C、δ18O的分析,结果表明:(1)研究区的各类岩石的δ18O比奥陶纪海水的要偏负,而岩溶作用微弱的原岩其δ13C则与奥陶纪海水的相当;(2)随岩溶作用的加强,岩石中的δ13C、δ18O降低,且δ18O对岩溶作用反应更灵敏;(3)岩石溶孔中的充填物与原岩的δ13C和δ18O含量相当,表明其与原岩形成于同一流体源,应属同期沉积的岩溶产物,即形成于沉积物形成之后不久,成岩环境属于近地表环境。另外,通过对研究区各种岩石Sr含量的研究,以及Sr/Ca、Sr/Ba和B元素对成岩流体盐度的反应分析,结果显示研究区曾经有大量的淡水注入,低Sr含量和高Fe2+/Fe3+值则说明了沉积物曾经历过深部岩溶作用。Abstract: The nicer karst reservoirs were formed at the top of the Ordovician Majiagou formation in Ordos basin due to tectonic uplift and erosion during the Caledonian movement.Based on analysis of δ13C and δ18O in dissolution pore fillings, karst breccia cements and carbonate rocks, the results showed that,(1)The δ18O value of various types of rocks is lower than that of the Ordovician seawater in study area while the δ13C value of weak karstification original rock is similar to that of Ordovician seawater;(2)With intensified karstification, the δ18O and δ13C of rocks decreased, and the δ18O value was more sensitive;(3)Fillings in dissolved pore and bedrock formed in the same fluid source, which should be the synsedimentary product of karst. In the paper, based on the values of Sr and the analytic of Sr/Ca, Sr/Ba and B elements which responded to the diagenetic fluid salinity, it may be concluded that there was a large freshwater input into the study area. The low Sr content and high Fe2+/Fe3+ value illustrated that sediments had undergone burial karstification.
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Key words:
- Jingbian /
- soluble rock /
- trace elements /
- carbon and oxygen isotope /
- geochemical characteristics
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[1] 李振宏,郑聪斌.古岩溶演化过程及对油气储集空间的影响——以鄂尔多斯盆地奥陶系为例[J].天然气地球科学,2004,15 (3):247-252. [2] 李振宏,郑聪斌.鄂尔多斯盆地东部奥陶系储层特征及控制因素[J].天然气地球科学,2004,15 (6) :604-609. [3] 章贵松,郑聪斌.压释水岩溶与天然气的运聚成藏[J].中国岩溶,2000,19 (3):199-205. [4] 郑荣才,陈洪德,刘文均, 等.川北大安寨段储层深部热水溶蚀作用[J].石油与天然气地质,1996,17 (4) :293-302. [5] 侯方浩,方少仙,董兆雄,等.鄂尔多斯盆地中奥陶统马家沟组沉积环境与岩相发育特征[J].沉积学报,2003,21(1):106-112. [6] 侯方浩,方少仙,赵敬松,等.鄂尔多斯盆地中奥陶统马家沟组沉积环境模式[J].海相油气地质,2002,7(1):38-46. [7] 侯方浩,方少仙,赵敬松.鄂尔多斯盆地奥陶系碳酸盐岩储层图集[M].成都:四川人民出版社,2002:32-36. [8] Allen J R,Wiggins W D.Dolomite reservoirs:Gochemical techniques for evaluating origin and distribution (AAPG Continuing Education Course Note Series No.36)[M].Tulsa:AAPG,1993:36-129. [9] Popp B N,Anderson T F,Sandberg P A.Brachiopods as indicators of original isotopic compositions in some Paleozoic limestones[J].GSA Bull,1986,97(10):1262-1269. [10] Lohmann K C,Walker J C G.The 18O record of Phanerozoic abiotic marine calcite cements[J].Geophys Res Lett,1989,16(4):319-322. [11] Montanez I P,Read J F.Fluid-rock interaction history during stabilization of early dolomites,upper Knox Group (Lower Ordovician),U.S.Appalachians[J].J Sediment Res,1992,62(5):753-778. [12] 王保全,强子同,张帆,等.鄂尔多斯盆地奥陶系马家沟组马五段白云岩的同位素地球化学特征[J].地球化学,2009,38(5):472-479. [13] 刘小平,吴欣松,张祥忠.轮古西地区奥陶系碳酸盐岩古岩溶储层碳、氧同位素地球化学特征[J].西安石油大学学报(自然科学版),2004,19(4):69-71,76. [14] 邓平.微量元素在油气勘探中的应用[J].石油勘探与开发,1993,20(1):27-32. [15] 贾振远.碳酸盐沉积相和沉积环境[M].武汉:中国地质大学出版社,1989:40-43. [16] 刘岫峰.沉积岩实验室研究方法[M].北京:地质出版社,1991:156-160. [17] Veizer J, Demovic R. Environmental and climatic controlled fractionation of elements in the Mesozoic carbonate sequences of the western Carpathians[J].Jonrnal of Sedimentary Research, 1973,43 (1):258-271. [18] Veizer J, Demovic R.Strontium as a tool in facies analysis[J]. Jonrnal of Sedimentary Research, 1974, 44 (1):93-115. [19] 胡明毅.塔北柯坪奥陶系碳酸盐岩地球化学特征及环境意义[J]. 石油与天然气地质, 1994, 15(2) : 158-163. [20] 邵龙义. 湘中早石炭世沉积学和层序地层学[M ]. 北京: 中国矿业大学出版社, 1997:131-138. [21] 刘文均. 湖南泥盆系碳酸盐岩中锶的分布特点及其环境意义[J]. 沉积学报,1989, 7 (2):15-19. [22] 王宝清,徐论勋,李建华,等.古岩溶与储层研究[M].北京:石油工业出版社,1995:56-62. [23] 覃建雄,曾允孚.鄂尔多斯盆地东部下奥陶统白云岩地球化学研究[J].矿物学报,1994,14(1):22-31. [24] 刘宝珺,曾允孚.岩相古地理基础和工作方法[M].北京:地质出版社,1985:35-48. [25] 刘显凤,蔡忠贤,云露,等.塔河油田岩溶作用元素地球化学的特征响应[J].石油实验地质,2009,31(3):270-274. [26] 史基安,邵毅,张顺存,等.鄂尔多斯盆地东部地区奥陶系马家沟组沉积环境与岩相古地理研究[J].天然气地球科学,2009,20(3):316-324. [27] 汪凯明,罗顺社.燕山地区中元古界高于庄组和杨庄组地球化学特征及环境意义[J].矿物岩石地球化学通报,2009,28(4):356-364. [28] Walker C T.Evaluation of boron as a paleosalinity indicator and its application to offshore prospects[J].AAPG Bulletin,1968,52(5):751-766. [29] Walker C T,Price N B.Departure curves for computing paleosalinity from boron in illities and shales[J].AAPG,1963,47(5):833-841.
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