Simulating electromagnetic wave resistivity MWD tool 's response in stratified media using hybrid method and recursive matrix algorithm

Key words:  electric logging  hybrid method  recursive matrix algorithm  electromagnetic wave resistivity  measurement-while-drilling (MWD)  stratified media

Abstract:

The hybrid method and the recursive matrix algorithm were combined to compute the electromagnetic wave resistivity MWD tool 's response in cylindrically symmetrical 2-D stratified media. A matrix equation group for ascertaining all the coefficients was obtained according to the continuity condition of electromagnetic fields at the interfaces, which can be solved rapidly via a recursive algorithm. Thus the tedious mode of up-going and down-going waves was abandoned and the appearance of exponentially increasing terms has been prevented. The influence of borehole, invasion and collar groove on electromagnetic wave resistivity MWD tool 's response was analyzed by the combined hybrid and recursive matrix method. The results show that the influence of drilling fluid on the receiver coil 's response is weakened since the space occupied by the drilling fluid within the borehole is reduced by the existence of metal drilling collar. The influence of the collar groove on the MWD tool 's phase difference and amplitude ratio can be neglected, but the collar groove has exerted distinct influence on the single receiver coil 's phase and amplitude. The collar groove 's influence on amplitude is more obvious than that on phase.