天津塘沽地区东营组沉积环境分析

Sedimentary Environment Analysis on Dongying Formation in Tanggu Area,Tianjin

塘沽地热田是天津滨海新区地热资源比较富集的地段,古近系东营组为孔隙型热储,对其开发利用尚处于起步阶段。为了查明该组热储沉积特征,寻找地热流体有利富集区,笔者在对该区的区域地质构造特征、热储特征、岩性和测井曲线的综合分析的基础上,对其沉积环境进行了对比研究。结果表明:1)该组沉积环境为海陆过渡环境的三角洲相和河口湾相,自东Ⅲ段到东Ⅰ段显示沉积湖盆由扩张到收缩的变化规律。2)东Ⅲ段-东Ⅱ段沉积环境以近缘三角洲前缘,湖岸砂坝沉积为主,有利于地热流体富集,河头-塘沽以南为地热流体有利富集地段。3)东Ⅰ段的沉积环境大部分已演变为沼泽平原相,在东北部为分流河道沉积,砂层相对发育,为地热流体的有利富集段。

Tanggu geothermal field is an area rich in geothermal resources in Binhai New Area,Tainjin City.Dongying Formation stratum is a pore geothermal reserve,and its exploitation is still at the initial stage.In order to ascertain the depositional characteristics of the geothermal resources,search for rich geothermal zone,and provide basis for the exploitation of geothermal resources,we analysed the sedimentary environment of Dongying Formation through systematic investigation of structural feature,geothermal storage,lithological characters and geothermal well logs.It is suggested that： 1） the sedimentary environment of Dongying Formation belongs to shelf sea with delta and estuarine facies.East Section III to I revealed the variation of the sedimentary lake basin from extensional period to shrinkage period.2） East Section III to II is mainly delta front facies and lake sand bars.This variation is propitious to the geothermal fluid enrichement.The favorable geothermal region is the south part of Hetou-Tanggu.3） Most of East Section I changes into swamp-plain sediment.The sediment of the northeast part in this area is the distributary riverway facies with developed sand layer.Geothermal fluid is advantageously enriched in this region.