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实验的和数学的水泥胶结测井波的机理研究表明,井场计算机处理现在能够把井内流体影响从声波信号对变化着的水泥胶结强度的响应中分出来。按照传统的方法解释水泥胶结测井资料,即便井眼内存在水,也不考虑井内流体的影响。这些影响已被假设为可以忽略不计。但是,随着在CaCl_2、ZnBr_2和CaBr_2完井液中进行测井的数量的增加,水泥胶结测井曲线大的变化已变得很明显。斯仑贝谢公司内部文章表明,胶结测井曲线的幅度与测井仪器所处的流体的声阻抗有关,并提出应综合研究井中流体的影响。已研制出模拟井眼几何形状的数学模型和实验模型。在5、7、9 5/8in(127、177、244.475mm)的套管中,用改变井内流体密度、粘度和流体类型(声阻抗)进行了测量。采用相似的参数得到相应的数学模型。结果表明,水泥胶结测井曲线的幅度随着井内流体声阻抗的变化而发生显著的变化;例如,在11.5磅/加仑的CaCl_2流体中声波信号的幅度比在水中增大70%。因此,发展了流体补偿胶结测井,即对声幅作变化着的井内流体声阻抗的校正,使得测井值更直接地与水泥胶结质量有关。
Experimental and mathematical studies of the mechanism of cement-bonded well logging wave show that well-site computer processing now separates the fluid effects in the well from the response of the acoustic signal to varying cement bond strengths. Cement bond logging data is interpreted according to conventional methods and does not consider the effect of fluid in the well, even if water is present in the wellbore. These effects have been assumed to be negligible. However, as the number of logs in CaCl 2, ZnBr 2, and CaBr 2 completion fluids increases, large changes in the cement bond log curves have become apparent. Internal observations by Schlumberger indicate that the magnitude of the cement log curve is related to the acoustic impedance of the fluid in which the logging tool is located and that the effect of fluid in the well should be comprehensively studied. Mathematical models and experimental models have been developed to simulate wellbore geometry. In a casing of 5, 7, 95/8 in (127, 177, 244.475 mm), measurements were made with varying well density, viscosity and fluid type (acoustic impedance). Use similar parameters to get the corresponding mathematical model. The results show that the magnitude of the cement cementation well logs varies significantly with the acoustic impedance of the fluid in the well; for example, the amplitude of the acoustic signal increases by 70% in water at 11.5 pounds per gallon of CaCl 2 fluid. Therefore, the development of fluid-compensated cementing logging, that is, the correction of acoustic impedance in the well with varying sound amplitudes, has made the logging values more directly related to the cementing quality.