Study On The Design And Directional Detection Characteristics Of Electromagnetic Wave Resistivity Logging-while-drilling Tools

In this paper,we first use the dyadic Green function of the magnetic flux source to carry out numerical simulation of the response of the non-drilled formation electromagnetic wave resistivity logging tool in the anisotropic horizontal stratigraphic strata,which can be used to calculate the instrument's traditional phase shift and amplitude attenuation can also be used to calculate the instrument directional phase shift and amplitude attenuation.The energy function of the instrument in the formation is calculated by using the Green function of the radial layered isotropic medium considering the condition of the metal drill collar.Based on the numerical simulation algorithm,the theoretical analysis of Schlumberger's PeriScope 15 and Halliburton ADR was carried out.The numerical simulation technique was used to study the prediction ability and ultra-deep detection capability of PeriScope 15 and ADR to the undeveloped stratigraphic interface.In order to obtain the conductivity parameters of the formation and to accurately indicate the existence of the interface,this paper optimizes the position of the antenna array along the axis of the instrument in the LWD instrument,which can make the signal from the front of the receiver The signal around the instrument to the maximum decoupling,and then to solve this problem.Calculations proves that as long as the scientific definition of the way,in the drilling of electromagnetic wave resistivity logging tool in the launch antenna and receiving antenna,whether it is used in cross-arrangement or sequential arrangement of the drill from the front of the formation of the signal and the instrument from the surrounding area of the maximum signal decoupling.The directional measurement signal after symmetric compensation coil is sensitive to formation dip and formation anisotropy only when it is close to the boundary of the formation.The directional measurement signal in the formation is no longer sensitive to formation anisotropy and formation relative inclination.Calculations proves that If the instrument is far away from the formation boundary with arbitrary resistivity,the measured signal of the directional amplitude attenuation and the directional phase shift are both zero;When the instrument is near the upper low-resistance rock in the high-resistance target layer,the measurement of the directional amplitude attenuation and the directional phase shift is positive,when the instrument in the high resistance of the target layer near the lower low resistance to the surrounding rock when the amplitude attenuation and directional phase shift measurement signal are negative,so the symbols are the opposite.When the instrument is close to the same boundary from any side of the formation boundary,the measured signal is monotonically increasing or decreasing in the same direction;The greater the difference in conductivity between the boundary surfaces,the greater the peak value of the measured signal at the boundary of the formation,the stronger the directional measurement signal.The use of the above signs can be predicted early to predict the existence of non-drilling low-resistance stratum and the upper and lower parts,so as to adjust the drilling instrument in time to keep it in the high resistance target layer.