天津中南部地区奥陶系地热流体层控性

Stratabound of Ordovician geothermal fluid in central and southern area of Tianjin

在天津中南部地区,奥陶系地热井成功率较低(66.67%)。通过岩石、岩溶、构造等条件,对奥陶系热储层控性进行研究。结果表明,本区奥陶系顶部风化壳岩溶条件不足,能够形成经济热储的地质作用主要是压释水岩溶作用和热水岩溶作用,且两种作用均与地质构造相关,具有不同的岩溶特征:风化壳"击穿"、褐铁矿被蚀变成硫铁矿、晶体大小不等是上覆地层压释水对下伏奥陶系进行岩溶作用的重要特征;节状构造、嵌晶结构、硫铁矿不发育及风化壳保存完好是发生热水岩溶作用的重要特征。这些特征及与构造相关性可成为寻找热储的标志。

In the central and southern area of Tianjin, the success rate of Ordovician geothermal well is only 66. 67%. The stratabound of Ordovician geothermal fluid has been studied through the conditions of rocks, karst and construct. The result shows that the karst on the top of Ordovician, was not enough in condition of weathering crust. The geological formation which can form economical storage of geothermal fluids, has mainly compaction re- leased water karst and hydrothermal karst. Both karstifications are related with the geological structures and differ- ent in karst characteristics. The weathering crust was ＂breakdown＂, limonite was eroded into pyrite, and different crystal sizes are typical in characteristics of karstification by overlying compaction released water to underlying Or- dovician. Section-like structure, poikilitic texture, pyrite not developed and weathering crust well preserved are important characteristics of hydrothermal karstification. These characteristics and the relationship with the structure can be a symbol for finding the reservoirs.