Method of determining the position of a downhole tool in a borehole

Abstract

A method and a system of determining the position of a downhole tool in a borehole includes the steps of: introducing a downhole tool that has an actuating tool and a downhole measurement device into the borehole, receiving downhole data representing the borehole, where the downhole data include at least a first downhole landmark position representing a location of a landmark in the borehole, receiving a first signal from a downhole measurement device, the first signal representing a downhole landmark of a borehole and a measured position of the downhole landmark, comparing the first signal to the first landmark position of the downhole data and generating a first correction value, generating a first corrected depth value by correcting the first signal with the first correction value, and transmitting a first actuating signal to actuate the actuatable tool in a downhole position based on the first corrected depth value.

What is claimed is: 
     
         1 . A method for determining a position of a downhole tool in a borehole, the method comprising:
 introducing a downhole tool into the borehole,   wherein the downhole tool comprises an actuating tool and a downhole measurement device;   receiving downhole data representing the borehole,   wherein the downhole data include at least a first downhole landmark position representing a location of a landmark in the borehole;   receiving a first signal from a downhole measurement device,   wherein the first signal represents a downhole landmark of a borehole and a measured position of the downhole landmark;   comparing the first signal to the first downhole landmark position of the downhole data and generating a first correction value;   generating a first corrected depth value by correcting the first signal with the first correction value; and   transmitting a first actuating signal to actuate the actuatable tool in a downhole position based on the first corrected depth value.   
     
     
         2 . The method of  claim 1 , wherein the first signal comprises a first landmark signature. 
     
     
         3 . The method of  claim 1 , wherein the downhole measurement device is a magnetic measurement device. 
     
     
         4 . The method of  claim 1 , wherein the downhole measurement device comprises two or more magnetic measurement devices. 
     
     
         5 . The method of  claim 1 , wherein the first signal comprises two or more measurement channel signals. 
     
     
         6 . The method of  claim 1 , wherein the downhole landmark in a borehole is a casing collar. 
     
     
         7 . The method of  claim 1 ,
 wherein the downhole data and/or the first signal are received by a computing device at a surface, and/or   wherein the comparing, generating, and/or transmitting step is performed by a computing device at the surface.   
     
     
         8 . The method of  claim 1 , wherein the downhole data is in the form of a list comprising details of well tubulars and/or casings that have been introduced into the borehole. 
     
     
         9 . The method of  claim 1 , wherein the downhole measurement device is part of the downhole tool. 
     
     
         10 . The method of  claim 1 , wherein the comparing comprises generating a first data window based on the downhole data for providing an acceptable position of a measured downhole landmark from the first signal. 
     
     
         11 . The method of  claim 1 , wherein the comparing comprises analyzing the data of the first signal within a first data window. 
     
     
         12 . The method of  claim 1 , wherein the first signal has a standard deviation and/or a variance that is utilized to identify a measured downhole landmark candidate. 
     
     
         13 . The method of  claim 1 , wherein the comparing defines a detection probability of a measured downhole landmark and/or identifies a measured downhole landmark when the detection probability meets a threshold. 
     
     
         14 . The method of  claim 1 , further comprising moving the downhole tool in accordance with the first corrected depth value. 
     
     
         15 . A system for determining a position of a downhole tool in a borehole, the system comprising:
 a downhole tool configured to be introduced into the borehole,   wherein the downhole tool comprises an actuatable tool and a downhole measurement device; and   a computing device positioned on a surface and connected to the downhole tool via a communication pathway,   wherein the computing device is configured to:
 receive downhole data representing the borehole, 
 wherein the downhole data include at least a first downhole landmark position representing a location of a landmark in the borehole; 
 receive a first signal from a downhole measurement device, 
 wherein the first signal represents a downhole landmark of a borehole and a measured position of the downhole landmark; 
 compare the first signal to the first downhole landmark position of the downhole data and generating a first correction value; 
 generate a first corrected depth value by correcting the first signal with the first correction value; and 
 transmit a first actuating signal to actuate the actuatable tool in a downhole position based on the first corrected depth value.