Theoretical Research On The Cross Dipole Acoustic Logging And High Frequency Induction Logging

The anisotropy of the stratum can be studied by calculating wave in the X and Y directions using the cross dipole acoustic logging to get reliable anisotropy azimuth. The premise is the same excited transverse vibration amplitude in the X and Y directions and the same response time of the transmitting and receiving probes.It is the impact on the measurement of the azimuth, when it is inconsistent that the amplitude and response time of the waves launched by probes in the X and Y directions. In the time domain, the more difference of the transversal wave amplitudes in the two directions, the more scattered of the distribution of the azimuth calculated in the different time, and it is not easier to obtain the accurate value. But when the amplitude difference is not smaller than 4%, the azimuth of which the frequency is the biggest deviates from the true value. Response time difference affects the value of the azimuth, but has little effect on its distribution. In the frequency domain, the more difference of the transversal wave amplitudes in the two directions, the more scattered of the distribution of the azimuth calculated in the different frequency. But when the amplitude difference is not bigger than 10%, in certain frequency bands between the azimuth and frequency asymptote is true azimuth. Response time difference affects the value of the azimuth, but has little effect on its distribution.An adjusted method is proposed. A group of waves are measured in the pure or not cemented casing wells, the amplitude ratio and the time difference of the waves is got by the inverse calculation of the X and Y directions basing on the received four waves, then the azimuth of the measured section is adjusted by using the amplitude ratio and the time difference, and it gives the accurate azimuth.Using the mixed programming on MATLAB and VC by MATCOM, the dipole longing data processing and interpretation system can calculate the azimuth in the frequency domain.Finally, basing on he three layer electromagnetic field model in induction logging, it is the effect of the mud resistivity and the invasion radius on the phase difference, and the effect of spacing and operating frequency on the probe depth that is analyzed ,when the mud resistivity under different circumstances. Simulation results show that: in the mud resistivity for 0.1-1Ω*m range, the invasion zone is small, and the mud resistivity is bigger, the phase difference of the invaded zone field is more approaching the phase difference of the infinity stratum. And in the mud resistivity is larger, the same frequency or spacing, the probe depth also have increased.