水文地球化学方法前兆机制的实验研究

借助油田的注水实验,我们研究了地下水化学成分的地震前兆机制。实验以10个井同时注水,注水深度为800～1200米。我们选用50～300米深的含水层作为水化学成分观测井。注水井的水源与观测井的含水层无关。当向800米以下深度注水时,该层压力增大,以此模拟从下层来的压力对水化学成分的影响。观测表明:当注水压力传递到上层含水层时,地下水化学成分便发生变化。其变化幅度与观测井的构造部位及地球化学环境有关,与观测井和实验注水井的距离关系不大。

EXPERIMANTL STUDY ON PRECURSORY MECHANISM BY HYDROGEOCHEMICAL METHOD

This paper deals with the mechanism of earthquake precursors on the basis of the chemical composition of underground water by means of injecting water test at an oil field. The test was carried out in the way that we made 10 wells simutaneously impounded up to a depth of 800-1200m. The observed well selected for analysing chemical composition of water is a water-bearing bed with its depth of 50-300m. The water source has nothing to do with the water-bearing bed of the observed wells, The pressure on the water-bearing bed increases as the impounding goes down up to the depth of 800m. The force for preparing earthquakes from the lower strata acting on the water chemical composition has been simulated by means of transmission of the increased pressure.The observed value indicates that the chemical composition of under ground water varies when the impounding pressure is transmitted up to upper water-bearing bed to cause stress-strain process. It is obvious that the variation amplitude is related to the well tectonic settings, and its geochemical surroundings, but scarcely to the distance of observed well and the testing water-injection well.