Determining Wellbore Position Within Subsurface Earth Structures and Updating Models of Such Structures using Azimuthal Formation Measurements

Abstract

A method for determining structure in the Earth's subsurface includes generating an initial model of the structure. The initial model includes at least one layer boundary. A wellbore is drilled along a selected trajectory through the Earth's subsurface in a volume represented by the initial model. At least one formation parameter is measured azimuthally along the wellbore. A distance is determined from the wellbore at selected positions therealong to the at least one layer boundary using the azimuthal formation parameter measurements. The initial model is adjusted using the determined distances. In one example, the parameter is resistivity. In one example, the parameter is acoustic velocity.

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       19 . A system for modeling a subsurface structure of the Earth, comprising:
 an instrument for measuring a formation parameter azimuthally along a wellbore drilled through a volume of the Earth's subsurface represented by an initial model;   a processor in signal communication with the instrument, the processor configured to determine a distance from the wellbore to at least one formation boundary in the volume from azimuthal measurements made by the instrument, the processor configured to adjust the initial model using the determined distance.   
   
   
       20 . The system of  claim 19  wherein the formation parameter is resistivity. 
   
   
       21 . The system of  claim 19  wherein the formation parameter is acoustic velocity. 
   
   
       22 . The system of  claim 19  wherein processor is configured to accept at least one of seismic and electromagnetic survey data to generate the initial model. 
   
   
       23 . The system of  claim 19  wherein the processor is configured to accept well log data to generate the initial model. 
   
   
       24 . The system of  claim 1  wherein the processor is configured to accept measurements of at least one additional petrophysical parameter along the wellbore and is configured to refine the initial model using the at least one additional petrophysical parameter. 
   
   
       25 . The system of  claim 24  wherein the at least one petrophysical parameter comprises at least one of acoustic velocity, natural gamma radiation, neutron porosity, density, nuclear magnetization transverse relaxation time, nuclear magnetization longitudinal relaxation time, permeability and formation fluid pressure. 
   
   
       26 . The system of  claim 24  wherein the processor is configured to accept measurement of the at least one additional petrophysical parameter during the drilling of the wellbore. 
   
   
       27 . The system of  claim 19  wherein the processor is configured to accept measurements of the at least one formation parameter during the drilling of the wellbore. 
   
   
       28 . The system of  claim 19  wherein the instrument includes means for propagating an electromagnetic wave at a first position along the wellbore and means for measuring at least one of a phase shift and an amplitude change of the wave at a second position along the wellbore. 
   
   
       29 . The system of  claim 28  wherein the means for propagating and measuring at least one of phase shift and amplitude includes antennas having dipole moment oriented in a direction offset from a longitudinal axis of the instrument. 
   
   
       30 . The system of  claim 19  wherein the processor is configured to measure a seismic travel time from the Earth's surface to the wellbore at least one position along the wellbore and adjusting the initial model using the seismic travel time. 
   
   
       31 . The system of  claim 30  wherein the processor is configured to calibrate the seismic travel time with respect to depth in the subsurface using checkshot data obtained from a substantially vertical wellbore drilled in a volume of the Earth's subsurface represented by the initial model. 
   
   
       32 . The system of  claim 19  further comprising means for transmitting the azimuthally measured parameter to the Earth's surface substantially in real time and the processor is configured to adjust the initial model substantially in real time. 
   
   
       33 . The system of  claim 32  wherein the means for transmitting comprises at least one of an optical fiber and an electrical conductor associated with a drill string. 
   
   
       34 . The method of  claim 14 , further comprising transmitting seismic travel time data to the surface via a wired drill pipe. 
   
   
       35 . The method of  claim 18 , wherein the azimuthally measured parameter is transmitted to the Earth's surface via a wired drill pipe.