摘要
给出了没有井眼条件下和有井眼条件下裂缝反射纵波的传播时间公式 ;证明无论阵列接收波形或变密度波形 ,其反射波的到达时间都是双曲函数 ;讨论了入射纵波在裂缝上的反射点构成的空间分布 ,它们分布在临界折射纵波时间和临界折射横波时间两个椭圆之间 ;探测最远距离是椭圆的短轴 ,对应于垂直裂缝 ;详细说明了探测裂缝存在的盲区 ;用模拟的变密度波形图显示了裂缝反射波的许多特点 ,这些特点是正确地识别和处理反射波的重要根据 ;建议在阵列声波仪器下面用电缆加接 1个发射声源 。
The reflected compressional wave from fracture can be used to detect fractures near borehole. This article described propagation time formulas of reflected compressional waves in formation with and without borehole; The relationship between reflected wave and the depth is hyperbola function, no matter in array receiving wave or variable wave. The spacial distribution area of reflected points of incident wave in fractures is situated between two ellipses that are determined by critical refracted P wave and critical refracted S wave. The farthest distance of fracture that can be detected is the short axis of ellipse, which corresponds to vertical fracture. The fracture areas that can′t be detected are existed and discussed in detail. The simulated variable density log map shows many important features of reflected waves, which are the base for identification of the reflected wave. It is a good method to detect fracture by adding a transmitting acoustic source under the array acoustic machine with cable.
出处
《测井技术》
CAS
CSCD
2002年第3期190-193,197,共5页
Well Logging Technology
