摘要
利用鄂尔多斯盆地姬塬地区319个实际测试的长6油层组地层水分析资料,研究了地层水类型、化学成分、离子比例系数、矿化度特征及其平面分布规律,揭示了地层水特征与油藏聚集保存的关系。长6油层组地层水矿化度在中生界中整体偏高,为以Cl^-和K^++Na^+为主的CaCl_2Ⅴ型和Ⅳ型地层水,地层水钠氯系数平均值分布在0.49~0.53,脱硫酸系数平均值分布在5.8~7.2,变质系数平均值分布在40~51,地层总体封闭环境很好。姬塬地区长6油层组现今地层水总体处于封闭的流体动力环境,但在纵向和平面上存在一定的差异。在长6油层组顶部的长61段中,西部区域和东部区域地层水矿化度和变质系数总体较中部区域高、地层水钠氯系数和脱硫酸系数较中部区域低,总体反映了西部区域和东部区域流体动力环境的封闭性要好于中部区域。这与在西部区域和东部区域已发现的油藏比中部区域多有很好的吻合性,地层水所反映的现今流体动力环境条件较好地代表了油藏的富集保存程度,现今流体动力环境更弱的区域更有利于油藏的保存。
Based on 319 measured analysis data of formation water in Chang 6 pay zone of Yanchang Formation in the Jiynan area of the Ordos Basin, the features （e.g. type, chemical composition, ion ratio, and salinity） and planar distribution rule of formation water were investigated, and the implications of such features for hydrocarbon accumulation were revealed. Salinity of formation water of Chang 6 pay zone is overall higher in Mesozoic strata, where the formation water shows higher salinity, recording as CaC12-V and IV type with major ions of C1- and K＋＋Na＊, and the average values of Na＋/C1 coefficient, desulphidation coefficient and metamorphism coefficient range in 0.49-0.53, 5.8-7.2, and 40-51, respectively. The overall stratigraphic enclosed environment is fine. The current formation water in Chang 6 pay zone is in a closed fluid dynamic environment, with the features varying vertically and horizontally. In Chang 61 at the top of Chang 6 pay zone, the salinity and metamorphism coefficient of formation water in the western and eastern parts are generally higher than that in the central part, and the Na＋/C1- coefficient and desulphidation coefficient of formation water in the western and eastern parts are generally lower than that in the central part. This indicates that the sealing capacity of the fluid dynamic environment in the western and eastern parts are better than that in the central part. It coincides with the fact that there are more oil reservoirs discovered in the western and eastern parts than that in the central part. The present fluid dynamic environment reflected by the formation water can effectively represent the accumulation and preservation degree of oil reservoirs, and the regions with weaker present fluid dynamic environment are more favorable for oil reservoir preservation.
作者
李士祥
楚美娟
王腾飞
张文选
周新平
Li Shixiang Chu Meijuan Wang Tengfei Zhang Wenxuan Zhou Xinping(National Engineering Laboratory for Exploration and Development of Low-permeability Oil ＆ Gas Fields Exploration and Development Research Institute ofPetroChina Changqing Oilfield Company)
出处
《中国石油勘探》
CAS
北大核心
2017年第5期43-53,共11页
China Petroleum Exploration
基金
国家重点基础研究发展计划(973)项目"淡水湖盆细粒沉积与富有机质页岩形成机理"(2014CB239003)
国家科技重大专项"大型油气田及煤层气开发"(2017ZX05001002)
关键词
矿化度
流体动力环境
地层水化学特征
长6油层组
姬塬地区
salinity, fluid dynamic environment, chemical feature of formation water, Chang 6 pay zone, Jiynan area
