摘要: 为揭示中国东部新生代浅部地层水化学场响应及油气意义,在东营凹陷新近系试油资料统计分析的基础上,对东营凹陷新近系的水化学场特征进行了研究。结果表明,与古近系沙河街组三段与四段封闭性滞留型水化学场特征明显不同,新近系馆陶组和明化镇组总体以低矿化度的NaHCO3型地层水为主体(矿化度小于5 g/L);其水化学剖面宏观上具有一定的分带性,大致可以划分为3种水文环境:强开放性水文流畅带(0~0.7km)、弱开放性水文阻滞过渡带(0.7~1.1km)和相对封闭性水文迟缓带(>1.1km);在不同的水化学作用带,水岩作用和地层水矿化度、离子和离子参数具有不同的响应;东营凹陷新近系Ca相对海水富集(Caexcess)和Na相对海水亏损(Nadeficient)的定量关系Caexcess≤0.2367Nadeficient-0.6261,显示出明显的钠亏损特征,钙富集量也远低于世界盆地流体线(Basin Fluid Line,BFL;Davisson,1996)所代表的富集量,与同凹陷古近系沙三、沙四段封闭性水文地质系统中钠相对富集特征也明显不同,反映了地层水蒸发浓缩作用弱及与地表水交替活动强烈的水文地质作用特征;地层水化学场的分布影响了原油密度和天然气的分布规律,使得东营凹陷新近系原油密度与天然气相对密度在剖面上的分布规律与地层水分有良好的一致性。
关键词:
地层水,
水岩作用,
油气分布,
新近系,
东营凹陷
Abstract: On the basis of calculation and analysis of abundant testing data,the characteristics of formation water in the Neogene of Dongying Sag was investigated to show the response of formation water fields of the Neozoic shallow strata in the eastern China.The results showed the obvious differences of the characteristics of the sealing and stagnating formation water chemical field in the Members 3 and 4 of Paleogene Shahejie Formation of Dongying Sag.The Neogene including the Guantao and Minghuazhen Formations is dominated by NaHCO3 type of formation water with low total salinity(generally less than 5 g/L). According to the vertica1 characteristics of the formation water,three hydrological environments can be classified: Strongly opening formation water alternation belt(0~0.7km),weak-opening formation water alternate blocking belt(0.7~1.1km)and relatively closing formation water alternate tardy belt(>1.1km).In every belt the total salinity,ions and ion composition ratio had different responses.Comparative to sea water the quantitative relationship between the enrichment of Ca(Caexcess)and the losses of Na(Nadeficient)of the Neogene in Dongying Sag(Caexcess≤0.2367Nadeficient-0.6261)shows the obvious characteristics of Na losses,and the enrichment of Ca(Caexcess)is far lower than the Basinal Fluid Line established by Davisson(1996).This response is obviously different to the Na enrichment in the formation water of the Members 3 and 4 of Paleogene Shahejie Formation closing hydrological-geological system in the same sag.The response of the Neozoic formation water field in Dongying Sag reflects weak evaporation and concentration effect of formation water and strong alternate activities with surface water.Affected by the response of formation water field,the distribution of the relative density of crude oil and natural gas in burial-depth profile has good consistency with vertical zonation of formation water.
Key words:
formation water,
water-rock interaction,
distribution of oil and gas,
Neogene,
Dongying Sag
中图分类号:
陈中红, 王书南, 王黎, 查明. 山东东营凹陷新近系地层水化学场特征及油气意义*[J]. 古地理学报, 2012, 14(5): 685-694.
Chen Zhonghong, Wang Shunan, Wang Li, Zha Ming. Characteristics of formation water chemical fields and its petroleum significance of the Neogene in Dongying Sag, Shandong Province[J]. JOURNAL OF PALAEOGEOGRAPHY, 2012, 14(5): 685-694.