声波测井1401

1、 声波测井1 Acoustic Logging 声波测井是以声波传播理论为基础的测井方法的总称，具体的测井方法包括补偿声波测井，偶极子横波测井，固井质量测井，声波电视测井，长源距声波测井等等。11 声波测井基础21.1 发声原理声波是一种波，波的产生与振动相联系。声带振动，乐器弦、表面的振动。声带的振动。1.2 压电陶瓷与换能器3压电陶瓷晶体在压力的作用下，产生电场。压力消失以后，压电晶体恢复原形。交变压力引起压电陶瓷晶体的交变电场和复原，交变电场就是电信号。压力在压电陶瓷中产生电信号的现象，叫压电效应。1.2 压电陶瓷与换能器4压电陶瓷晶体在电场的作用下，产生形变。电场消失以后，压电晶体恢复

2、原形。交变电场引起压电陶瓷晶体的反复形变和复原，就是振动。电场引起压电陶瓷形变，并对空气形成压力，叫逆压电效应。压电晶体的形变和复原，引起空气振动，产生声波。真空中压电陶瓷振动会有声波吗？常用的压电陶瓷5测井中，根据压电陶瓷的压电效应和逆压电效应，使用压电陶瓷产生声波和接收声波。此时的压电陶瓷称为换能器-完成电能与声能之间互相转换。1.3 声波的产生和接收6TR发射系统中的电源，对压电陶瓷（T）施加交变电场。由于逆压电效应，压电陶瓷（T）发生形变，产生声波。这个声波在传播过程中，产生一定的压力。压力作用在压电陶瓷R上，由于压电效应，压电陶瓷R中产生电信号。这个系统完成声波的产生和接收。但这个系

3、统不具实用价值。1.4 井筒中声波的传播71.4.1 声波的传播速度1(1)(12)2(1)12pbsEVVVp，Vs，分别为声波的纵波传播速度和横波传播速度。注意公式变量的单位。纵波与横波的振动方向与传播方向81.4.2 声波的反射和折射- 斯奈尔定律91mps2mSP井筒地层sinsinmmppVVsinsinmmssVVpsmpsmVVV10psmpsmVVV产生滑行纵波和横波第一临界角1m，产生滑行纵波；第二临界角2m，产生滑行横波。1mp1mP井筒地层S2p2s哪一个临界角更大一些？11只有在比较致密，声速较大的岩层中，才可能产生滑行横波1.5 声波的衰减声波在传播过程中，声波引起岩

4、石颗粒之间的摩擦，能量逐渐消耗。12L：声波传播距离， 米；2 补偿声波测井 BoreHole Compensated Tool 2.1 测量声系结构 两个声波发射器组成发射探头T1，T2；两个声波接收器组成接收探头。都是压电陶瓷，对称排列。1311121.0 ,0.5 ,T RmR Rm称为源距；称为间距。2.2 声波时差测量原理T1发出的声波，经过路径ABCDEF,分别被R1和R2接收。1412mtmmtmABBCCDtVVVABBCCEEFtVVV假设井眼规则，仪器居中。为什么要采取双发双收的测量系统？接收探头的接收信号时间差tttmtttR REFCDCECE

5、tVVVVR RE FC DC EC EtVVVVttt 121ttt假设井眼规则，仪器居中。为什么要采取双发双收的测量系统？2.3 滑行波的接收条件16要求最先接收滑行波，尽可能延迟衰减直达波。： 井壁到探头的距离费尔马时间最小原理。测井仪器国产化过程中碰到的问题。l隔声体1722 tan( )cos( )0sinmtmtlLlxt xVxVdt xdxVxVl，井壁到探测器之间的距离。声波传播路径最短。直达波传播时间大于滑行波传播时间182 tan2cosmtmLLlxlVVVx2.3 井眼不规则补偿 对井眼不规则和仪器偏移均具有补偿作用19121122122mtttmtttR REFCD

6、CECEtVVVVR RE FC DC EC EtVVVVttt T1发出的信号，由于CD增加，R1被触发的时刻偏晚，结果使t1减少；同理，T2发出的信号，由于EF增加，R1被触发的时间偏晚，使t2增加；2.4 周波跳跃20信号衰减，触发波形的相位发生变化。使测量声波时差不规则增大或减小。主要出现在气层或裂缝段。测井实例21周波跳跃 2.6 补偿声波测井的分辨率22(tan,)LtRfL对于高速地层，t增加，导致RL增大，即仪器的分辨率降低。单发双收仪器，仪器的分辨率为L。CC是仪器的分辨能力。缩短间距，可以提高仪器分辨能力。高分辨能力的仪器可以划分较薄的储层。间距太小会有什么问题？2.7 探

7、测盲区23盲区：两个发射探头声波路径不重叠的部分。有盲区和没有盲区的传播路径。主要出现在低速地层。sinmtVxVx2.8 补偿声波测井资料的解释2.8.1 声波时差的记录24121122122mtttmtttR REFCDCECEtVVVVR RE FC DC EC EtVVVVttt 121tttVt，地层的声波速度。已知量和未知量记录的声波时差为2521211122121212122tttttLR RtttttLR Rttt 单位距离上的时间差为时差(慢度)2.8 补偿声波测井资料的解释2.8.2计算地层的孔隙度2611.680.0002mapfmapttCttCH :声波孔隙度；t，声

8、波测量值；tma: 骨架声波时差；tf，孔隙流体时差；Cp: 压实压实校正系数； 注意单位取一致。SpDCD相当于回归统计法确定声波孔隙度27iiatb将岩心分析孔隙度与声波测井时差一一对应，用最小二乘法确定公式的系数a、b。2.8.3 判断气层28周波跳跃或声波时差明显增大2.8.4 判断压实异常29测量声波时差偏离正常趋势线。30横波测量数据是弹性参数计算的必要资料2.8.5 计算岩石的弹性参数密度，后续课程介绍横波测井31横波数据Leg-184 logging Tools323 长源距声波测井 Long-spaced Sonic Tool 3.1 测量声系33两个发射探头和两个接收探头。

9、T1,T2;发射探头和接收探头分别为单边排列R1,R2;为了减小仪器的长度。希望增大仪器的探测范围，增大仪器的源距。341.0 1.0 0.52.5TL增加仪器的长度有限。组合仪器的长度达到20.0米左右。3.2 测量原理35R1R2=0.61mT1R2=2.44m分别组成两个单发双收声系（T1-R1-R2，T2-R1-R2）和两个双发单收声系(T1-R1-R2， T1-R1-R2)。第一种测量源距，2.66 米。在目的层，T1发射，R1，R2接收。然后仪器上移，当T1，T2到达目的层的同一位置时，T1，T2同时发射，R1接收。此时的声系相当于源距2.44米的双发双收声系。36R1R2=0.6

10、1mT1R2=2.44m分别组成两个单发双收声系（T1-R1-R2，T2-R1-R2）和两个双发单收声系(T1-R1-R2， T1-R1-R2)。第二种测量源距，3.05 米。在目的层，T2发射，R1，R2接收。然后仪器上移，当T1，T2到达目的层的同一位置时，T1，T2同时发射，R2接收。此时的声系相当于源距3.05米的双发双收声系。37R1R2=0.61mT1R2=2.44mR1R2=0.61mT1R2=2.44m3.05米声系 2.44米声系3.3 测井数据应用3.3.1 测量纵波时差和横波时差 可用于计算岩石的力学参数和地应力评价。3839井筒稳定性条件分析3.3.2 斯通利波确定储层

11、的渗透率斯通利波幅度、速度与渗透率有关系。斯通利波衰减能量大，渗透率高；反之，渗透率低。403.3.2 识别岩性41纵波横波交绘图的方法，根据数据点的位置，确定资料点深度的岩性。4 Porosity Logs42Rock porosity can be obtained from the sonic log, the density log, or the neutron log. For all these devices, the tool response is affected by the formation porosity, fluid, and matrix. If the f

12、luid and matrix effects are known or can be determined, the tool response can be related to porosity. Therefore, these devices are often referred to as porosity logs.All the three logging techniques respond to the characteristics of the rock immediately adjacent to the borehole. Their depth of inves

13、tigation is very shallow only a few inches or lessand therefore generally within the flushed zone. 43In these case of well logging, the borehole wall, formation bedding, borehole rugosity, and fractures can all represent significant acoustic discontinuities. Therefore, the phenomena of wave refracti

14、on, reflection, and conversion lead to the presence of many acoustic waves in the borehole when a sonic log is being run. It is not surprising, in view of these consideration, that many acoustic energy arrivals are seen by the receivers of a sonic logging tool. The more usual energy arrivals are sho

15、wn in the acoustic waveform displays of Fig.5-1. These waveforms were recorded with an array of eight receivers located 8 to 11-1/2 ft from the transmitter. The various wave packets have been labeled. Although the wave packets are not totally separated in time at this spacing, the distinct changes c

16、orresponding to the onset of the formation compressional and shear arrivals and the Stoneley arrival can be observed.444546The first arrival or compressional wave is one that has traveled from the transmitter to the formation as a fluid pressure wave, has been refracted at the borehole wall, has tra

17、veled within the formation at the compressional wave velocity of the formation, and has traveled back to the receiver as a fluid pressure wave.The shear wave is one that has traveled from the transmitter to formation as a fluid pressure wave, has traveled within the formation at the shear wave veloc

18、ity of the formation, and has traveled back to the receiver as a fluid pressure wave. 47The Stoneley wave is one of large amplitude that has traveled from transmitter to receiver with a velocity less than that of the compressional waves in the borehole fluid. The velocity of the Stoneley wave is dependent upon the