东营凹陷古近系古湖盆演化与水化学场响应

Response and evolution of formation water chemical fields of the paleogene in Dongying sag

东营凹陷古近系水化学场分布与湖盆演化有着良好的对应关系,以CaCl2水型为主的高矿化度地层水是东营凹陷古近系咸化湖盆的典型响应特征,矿化度从深到逐渐降低,体现出从咸化湖盆向微咸化湖盆及淡水湖盆演化的地球化学响应.剖面上可以划分为四种水文环境:强开放性水文流畅带(地表到1.1km)、弱开放性水文流畅带(1.1-2.0km)、水文阻滞过渡带(2.0-2.5km)和封闭性水文迟缓带(2.5km以下),水化学剖面的分带性与压力分布有着良好的对应关系.东营凹陷古近系水化学场经历了早期的沉积与淋滤的交替和新生代的埋藏封闭作用期,其中在东营运动时期古近系水化学场表现最为活跃,是深层卤水咸化地表浅层淡水从而使浅层出现高矿化度地层水的关键作用期,断裂的沟通起了重要作用,显示出断陷湖盆的典型特征.

The formation of water chemical characteristics in the Paleogene System had good response to the sedimentary conditions and its evolution in Dongying sag. The type of CaCl2 formation water with high salinity was representative response of the brine lake of the Paleogene System in Dongying sag. The content of total salinity and chloride ion decreased from the deep depth to the lower, which was good response to the evolution of the Dongying sag from salted basin to freshwater basin. According to the vertical characteristics of the underground water formation, four hydrological environments can be classified： stronger formation water frequency alternation belt（0-1.1km）, feeble formation water frequency alternation belt（1.1-2.0km）, formation water alternate blocking belt （2.0-2.5km） and formation water alternate tardy belt （〉2.5km）. In every belt the total salinity, ions and ion composition ratio had different responses, and the belts corresponded to the distribution of formation pressure. The formation water chemical field experienced deposition and leaching in early time and burial in later time. In the period of Dongying Movement the formation water chemical field was active, and salted water from the Member 4 of Shahejie Formation migrated to the lower, and in the course the faults played important roles, which demonstrated the representative characteristics of faulted basin.