Patent ID: 9556723
Date: 2017-01-31
CPC Classifications: E21B

Claim:
1. A method of estimating position of a borehole, comprising: disposing an acoustic sensor in a first borehole in an earth formation, the acoustic sensor including a plurality of measurement locations disposed along a length of the first borehole; drilling a portion of a second borehole in the earth formation using a drilling assembly; taking distributed acoustic measurement data over a time period during the drilling by the plurality of measurement locations, the acoustic measurement data based at least in part due to an acoustic signal generated by the drilling assembly and detected by the plurality of measurement locations, the acoustic measurement data including a plurality of traces collected over the time period, each of the plurality of traces associated with a different location along the first borehole; processing the measurement data to estimate a distance between the drilling assembly and the acoustic sensor, wherein processing includes cross-correlating the plurality of traces and calculating cross-correlation maxima including a cross-correlation maximum associated with each trace, generating a plot of the cross-correlation maxima, and estimating the distance based on an apex of the plot; and controlling directional parameters of the drilling based on the distance.