海相地层水文地球化学与油气保存条件评价

Study on hydrogeochemistry and evaluation technology of petroleum preservation conditions for marine strata

针对中国南方海相地层经历多期构造运动和油气藏破坏严重的问题,提出评价油气保存条件的水文地球化学方法.基于大气水下渗对油气藏保存具有破坏作用并淡化了地层水的原理,通过分析松潘-阿坝地区和十万大山盆地现今地下水动力特征,利用温泉和方解石脉稳定同位素资料,分别计算了现今和古大气水下渗深度.在分析中国典型海相盆地和南方海相地层水化学基本特征的基础上,对比地表水体的地球化学特征,总结了一套评价海相地层油气保存条件的水文地球化学综合指标体系.结果表明,中国南方海相地层油气保存条件总体较差,现今和古大气水下渗强烈.不同时代地层水被下渗大气水下渗淡化明显.

For resolving problems of undergoing many tectogenesises and heavy breach of oil-gas pools in South China in marine, a hydrogeochemical method for evaluating the petroleum preservation conditions was proposed. Based on the theory that the downward infiltration of meteoric water has actions of desalting strata water and destroying oil-gas pools, the present underground hydrodynamic characteristics of Songpan-Aba area and Shiwandashan basin were analyzed, and the downward infiltration depth of present and paleo-meteoric water was reckoned respectively by using hot spring and calcite stabilization isotope data. After the strata hydrochemical characters of typical marine basin and southern marine strata in China were studied and were contrasted with the geochemical characters of surface water, a systematical hydrogeochemical index system was summarized for evaluating petroleum preservation conditions in marine strata. The experimental results show that the petroleum preservation conditions are poor as a whole in South China marine strata, downward infiltration of present and paleo-meteoric water is strong. The stratum water in different epoch strata is obviously desalted.