深圳抽水蓄能电站水压致裂法三维地应力测量和分析

Measurement and analysis of three-dimensional geostress by hydraulic fracturing technique in Shenzheng Pumped Storage Power Station

由于水压致裂法地应力测量的突出优点已在国内外得到广泛应用,但以往只能测量钻孔横截面上的二维应力状态。近期兴起的水压致裂法三维地应力测量,已在多个工程中得到应用。深圳抽水蓄能电站采用了3个不同方向钻孔测量法和单钻孔测量法进行了三维地应力测量,得到了很好的测量成果。其中单钻孔三维地应力测量,在近水平向和铅垂向两个钻孔中应用。三维地应力测量成果不仅得到了相应钻孔横截面上和原生裂隙面上二维应力实测值的检验,而且得到了同一位置两种不同三维地应力测量方法的相互印证,和同一个钻孔(铅垂向)中套芯应力解除法三维地应力实测值的印证。两种水压致裂法三维地应力测量成果(单钻孑L测量法包含了非铅垂向和铅垂向钻孔的两种测量法)非常一致,能够代表该测量区的地应力状态。

Hydraulic fracturing as a technique of geostress measurement has been widely applied at home and abroad due to its many outstanding merits.But this measuring method is only used to the two-dimensional stress in a plane normal to the borehole axis in former time.Recently,the method of by hydraulic fracturing measurement of three-dimensional geostresses is prevalent and has been used successfully in many projects.In Shenzheng Pumped Storage Power Station,the three-dimensional geostresses have been measured by hydraulic fracturing technique to adopt two different measuring methods including in three boreholes with different directions method and in one borehole method,and the measured results are very satisfactory.The latter measuring method was applied in two boreholes that one is in vertical direction and the other one is in approximately horizontal direction.The three- dimensional geostress measured results not only checked the two-dimensional geostress measured stress states in the corresponding borehole's cross-section and preexisting fissure planes,but also the measured results of the two different measuring methods in the same place confirmed each other;and the measured results confirmed by the results obtained overcoring stress refief method in the same borehole.At the same time,the measured results of the two type methods are very consistent(one borehole measuring methods including non-vertical borehole and vertical borehole),and it can represent the geostess state in the measured area.