| 摘要 |
Conductivity determination of a formation comprises measuring the magnetic coupling between emitter and receiver coils in a tool in sounding a hole through the formation. The angle of direction of a tool relative to the formation, the initial angle of the tool, an initial anisotropic factor and an initial horizontal conductivity in the formation can then be obtained. The iterative anisotropic factor, an iterative horizontal conductivity and an iterative angle of incline can then be determined from these first data. Preferred Features: The iterations are repeated a number of times to minimize the global residual error. The angle of direction is beta , where beta = tan<1>((TzRy)x)/(TzRx)x), in which e.g. (TzRy)x is the reactive component of the coupling TzRy between a transmitter Tz oriented along the z axis and a receiver Ry oriented along the y axis. The initial angle of inclination is alpha , where alpha = tan<-1>(((TxRy)x)/(TzRx)x)<2> + ((TxRy)x)/(TzRy)x)<2>)<0.5>. The initial anisotropic factor is A1, where A1 = 1/(1 + ((TzRx)x(TzRx)R.tan alpha )/(TzRz)x (TzRz)R cos beta )), where (TzRz)x and (TzRz)R (e.g.) are the real and imaginary components of the coupling TzRz between a transmitter and receiver oriented along the z axis. The initial horizontal conductivity is sigma h1, where sigma h1 = K1(mod((TzRz)x(TzRz)R)/A1, where K1 is a predetermined function of the voltage and frequency of the emitted signal. The iterative anisotropic factor is Ai+1, where Ai+1 = 1/(1 + (((TzRx)x (TzRx)R - theta zx).tan alpha )/((TzRz)x (TzRz)R - theta zz) cos beta )), where theta zx and theta zz are first and second parietal effect corrections.
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