含油气盆地地层水演化过程中含烃酸性流体的浸入效应——以东营凹陷胜坨油田为例

Immersion effect of hydrocarbon-acidic fluid with evolution of formation water in oil-gas bearing basin-case study of Shengtuo oilfield,Dongying depression

为了认识油气成藏过程中地层水的变化规律,确认水—岩—油之间相互作用产生的成岩标志及对成藏的标识性,通过对胜坨油田重点钻井剖面岩心测试和地层水资料的分析,将东营凹陷地层水演化分为5个阶段,对应5种流体类型,分别为同沉积地层水(第1期流体)、混入型地层水(第2期流体)、含烃流体(第3期流体)、幕式含烃酸性流体(第4期流体)、碱性化流体(第5期流体)。研究发现,在第3和第4期流体活动过程中有大量的含铁碳酸盐、铁质集晶和自生高岭石等矿物。通过电子探针化学成分对比分析,证实其与油气主成藏期对应的含烃酸性流体有关。根据对含铁碳酸盐、铁质集晶和自生高岭石在岩体内分布规律的追踪,阐述了成岩与油气成藏的关联性,为深化油气成藏聚集规律认识和最终勘探目标的确定提供了一种新的决策依据。

The purpose herein is to understand the evolution rule of formation water during the process hydrocarbon accumulation, and determine the marker between the diagenetic and oil-gas accumulation which is caused by interaction among the water-rockoil. By analysis on core testing data and formation water information of important drilling profile in Shengtuo area,the formation water evolution in Dongying depression is divided into five stages,accordingly,there are five types of water:the contemporaneous formation water,the first fluid,the mixed formation water,the second fluid,the hydrocarbon fluid,the third fluid,the episodic hydrocarbon acid fluid,the fourth fluid,the alkalization fluid,the fifth fluid.It is revealed by the study that,among the third fluid and the fourth fluid,a lot of iron-carbonate,iron aggregate crystal,authigenic kaolinite and so on exist.By the electron probe analysis on its chemical composition,it was proved that it is related with hydrocarbon acid fluid in main accumulation stage.According to the distribution rule of iron-carbonate,iron aggregate crystal,authigenic kaolinite,the relationship between diagenetic and oil-gas reservoir is presented.A new exploration strategy is provided for oil-gas concentrated and accumulated deeply.