System and Method for Determining Three Dimensional Well Position

Abstract

A system and method for improving the 3D positional description of well geometry, subsurface measurements and subsurface services as provided along the wellbore and improve the provision of the 3D positional uncertainty. The method selects a well reference point, calibrates the AHD, Incl and Az measurements, selects a measurement station positioned, observes measurements at the measurement station, selects at least one or more additional measurement station(s), repeats the measurements, transforms calibrated interval AHD, Incl. and Az observed measurement values into V, N and E interval values, summates V, N and E interval values to create a 3D positional description of each measurement station. The method then determines the AHD, Incl. and Az value uncertainties at each measurement station, calculates and concatenates the AHD, Incl. and Az value uncertainties and creates a depiction of these associated uncertainties along the length of the wellbore in terms of V, N and E positions from ZDP.

1 - 42 . (canceled) 
     
     
         43 . A method for determining the 3D position of a wellbore, the method comprising the steps of:
 selecting a well reference point;   calibrating the AHD, Incl and Az. measurements   selecting a measurement station positioned in the wellbore where AHD, Incl. and Az observations are made;   observing AHD, Incl and Az measurements at the measurement station;   selecting at least one or more additional measurement station(s);   observing the AHD, Incl. and Az measurements at the additional measurement station(s);   transforming the calibrated interval AHD, Incl. and Az observed measurement values into V, N and E interval values;   summating the V, N and E interval values to create a 3D positional description of each measurement station,   determining the AHD, Incl. and Az value uncertainties at each measurement station over each observed interval;   calculating and concatenating the AHD, Incl. and Az value uncertainties at each sequential measurement station;   and creating a depiction of these associated uncertainties along the length of the wellbore and/or depicting these in terms of V, N and E positions from ZDP.   
     
     
         44 . The method as claimed in  claim 43  wherein the well reference point comprises a surface marker position or a drill floor or at a defined position along the wellbore. 
     
     
         45 . The method as claimed in  claim 43  wherein the well reference point is identified as having a defined 3D positional identification which is an elevation from a given surface datum elevation and a north and an east location identified using a geodetic positional reference. 
     
     
         46 . The method as claimed in  claim 43  wherein the well reference point comprises a zero depth point (ZDP) for a drilling rig or wellbore. 
     
     
         47 . The method as claimed in  claim 43  wherein, the well reference point is a wellbore sub-surface point identified as having a defined 3D position. 
     
     
         48 . The method as claimed in  claim 43  wherein, the position of the well reference point are subject to a given accuracy which is defined by a fixed uncertainty value for each dimensional measurement (ToolJointError). 
     
     
         49 . The method as claimed in  claim 43  wherein, the measurement stations are positions in the wellbore between which a wellbore trajectory is constant or near-constant. 
     
     
         50 . The method as claimed in  claim 43  wherein, the measurement station is positioned at the end of constant or near-constant and correction, AHD, Incl. or Az values. 
     
     
         51 . The method as claimed in  claim 43  wherein, the measurement station is positioned to account for changes in well geometry well architecture, or proximity to other well bores. 
     
     
         52 . The method as claimed in  claim 43  wherein, the measurement station is positioned to account for changes in geology and/or reservoir characteristics intercepted by the well bore. 
     
     
         53 . The method as claimed in  claim 43  wherein, each measurement station is identified along the wellbore at given well depths where by the interval to each subsequent measure station has a constant or near-constant AHD correction, Incl., and Az values. 
     
     
         54 . The method as claimed in  claim 43  wherein, AHD is measured using an observed drill pipe depth measurement. 
     
     
         55 . The method as claimed in  claim 44  wherein, the observed drill pipe depth measurement is calibrated and/or corrected for environmental and/or measurement influences such as temperature and drill pipe axial tension, are included in the reporting process. 
     
     
         56 . The method as claimed in  claim 44  wherein, AHD is measured using a wireline measurement and the observed wireline length measurement is calibrated and/or corrected for environmental and measurement influences such as temperature and wireline tension are included in the process. 
     
     
         57 . The method as claimed in  claim 43  wherein Az is measured using an observed drill pipe depth measurement. 
     
     
         58 . The method as claimed in  claim 43  wherein, Incl. is measured using an observed drill pipe or conveyed using any other wellbore tubular depth measurement. 
     
     
         59 . The method as claimed in  claim 43  wherein, further comprising the step of ascertaining the calibrated measurement value uncertainites of the V, N and E values is comprised of transforming the calibrated AHD, Incl and Az values and their accuracies into V, N and E uncertainty values through identifying those individual contributory elements of V, N and E from the observed values and the accuracies of AHD, Incl. and Az measurements. 
     
     
         60 . The method as claimed in  claim 43  wherein, subsurface data is synchronised to the calculated and presented 3D positional and/or positional uncertainty results. 
     
     
         61 . The method as claimed in  claim 43  wherein, the 3D position and uncertainty can be incrementally ascertained by making AHD, Incl. and Az measurements by drilling the wellbore deeper and then adding (a) further measure station(s), so that the position and uncertainty data is a series of increments defined by sequential additional of measure station 3D positions and the concatenation of sequential associated uncertainties. 
     
     
         62 . A computer system comprising program instructions or process logic for the operation of the method of  claim 43 .