Method and apparatus for logging the course of a borehole

• US 3,896,412 A
• Filed: 11/19/1973
• Issued: 07/22/1975
• Est. Priority Date: 11/19/1973
• Status: Expired due to Term

• Current Assignee: RWE-DEA Aktiengesellschaft für Mineraloel und Chemie
• Original Assignee: Ulrich Rohr
• Inventors: Rohr, Ulrich
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Moskowitz, N.
• Application Number:
  US05/417,445
• Time in Patent Office: 610 Days
• Field of Search: 181/15TS,102 175/45 73/151.5 33/174C,304,308,313 340/15.5BH
• US Class Current: 367/33
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: G01V 3/34 Transmitting data to recording or processing apparatus; Recording data

Abstract

The course of a borehole is determined by sending a logging tool down the borehole containing apparatus for measuring an angle of inclination phi and an azimuth angle theta . The signals are transmitted to surface electronics which also receives a signal corresponding to the rate dl/dt of descent of the logging tool into the borehole. A cartesian coordinate system having a reference point at the mouth of the borehole has three coordinates axis perpendicular to each other and identified as AN. AO and TV. The TV axis extends in a vertical direction, the AN axis extends in a horizontal northerly direction and the AO extends in a direction 90* from the AN and TV axial direction. The surface electronics is computer type apparatus which continuously converts the signals corresponding to the angle phi and theta and to the rate dl/dt to a point defining the position of the logging tool at the instant of measurement. As each point is recorded as the logging tool moves through the borehole, a record is made of the course of the borehole. The apparatus and method of the invention also provide for discontinuous operation either at the surface or in the transmission of signals of the logging tool.

Claims

1. A system for logging the course of a borehole comprising a logging tool including means for providing a theta signal corresponding to an azimuth angle theta , and means for providing a phi signal corresponding to an angle phi of inclination;

conduction means connected to all the signal means in the logging tool for conducting the signals to the surface, and surfAce electronics including means for providing a dl/dt signal corresponding to the rate of travel of the logging tool through the borehole;

means connected to the conducting means and to the dl/dt signal means for providing a Tv signal in accordance with the phi signal and the dl/dt signal, said Tv signal corresponds to a distance along an axis Tv of a cartesian coordinate system having its reference point at the mouth of the borehole, the axis Tv extends in a vertical direction;

means connected to the conducting means and to the dl/dt signal means for providing an AN signal in accordance with the phi , theta and dl/dt signals, said AN signal corresponds to a distance along an axis AN in the coordinate system which extends in a northern direction from the reference point, means connected to the conducting means and to the dl/dt signal means for providing an Ao signal in accordance with the phi , theta and dl/dt signals, said Ao signal corresponds to a distance along an axis Ao in the coordinate system which extends in a direction perpendicular to the directions of the Tv and AN axes.

2. A system as described in claim 1 in which the Tv signal means provides the Tv signal in accordance with the following equation:

3. A system as described in claim 2 in which the phi signal means provide a signal corresponding to sin phi as the phi signal, and the AN signal means includes means connected to the conducting means for providing a signal corresponding to theta 2 in accordance with the theta signal, means for providing signals corresponding to K1 through K4, means connected to the K signal means and to the theta 2 signal means for providing a signal corresponding to K1 theta 2, means connected to the last mentioned means for squaring the K1 theta 2 signal to provide a signal corresponding to K12 theta 4, means connected to the last mentioned means and to the K2 signal means for providing a signal corresponding to K12 K2 theta 4, means receiving the K12 K2 theta 4 signal and connected to the K1 theta 2 signal means for providing a signal corresponding to K13 K2 theta 6, means receiving the K13 K2 theta 6 signal and connected to the K signal means for providing a signal corresponding to K13 K2 K3 theta 6, first summing means connected to the last mentioned means and to the K1 theta 2 signal means for providing a signal corresponding to K1 theta 2+K13K2K3 theta 6, second summing means connected to the K12K2 theta 4 signal means and to the K signal means for providing a signal corresponding to K4+K12K2 theta 4, subtracting means connected to both summing means for subtracting the signal provided by the first summing means from the signal provided by the second summing means to provide a signal corresponding to COS theta , means connected to the subtracting means for inverting the signal from the subtracting means to provide a signal corresponding to -COS theta , first switching meanS connected to the inverting means, to the subtracting means and to the comparing means for passing either the COS theta signal or the - theta signal in accordance with the comparison signal from the comparing means, first multiplying means connected to the first switching means and to the conduction means for providing a product signal in accordance with the sin phi signal and the passed signal from the first switching means, second multiplying means connected to the dl/dt signal means and to the first multiplying means for providing a second product signal in accordance with dl/dt and the first product signal, and an integrator connected to the second multiplying means integrates the second product signal to provide the AN signal.

4. A system as described in claim 3 in which the Tv signal means includes means connected to the conducting means for providing a signal corresponding to sin2 phi in accordance with the sin phi signal, means receiving a direct current voltage corresponding to a value of 1 and connected to sin2 phi signal means for providing a signal 1-sin2 phi , means connected to the 1-sin2 phi signal means for providing a signal corresponding to cos phi , third multiplying means connected to the cos phi signal means and to the dl/dt signal means for providing a signal corresponding to dl/dt.cos phi , and a second integrator connected to the third multiplying means integrates the dl/dt.cos phi signal to provide the Tv signal.

5. A system as described in claim 4 in which the Ao signal means includes means connected to the switching means for providing a signal corresponding to cos2 theta , means receiving the direct current voltage corresponding to a value of 1 for providing a signal corresponding to 1-cos2 theta , means connected to the 1-cos2 theta signal means for providing a signal corresponding to sin theta , second inverting means connected to the sin theta signal means for providing a signal corresponding to -sin theta , second switching means controlled by the comparison signal from the comparing means to pass either the sin theta signal or the -sin theta signal in accordance with the comparison, fourth multiplying means connected to the second switching means and to the conducting means for providing a fourth product signal in accordance with the passed signal from the switching means and the sin phi signal, fifth multiplying means connected to the fourth multiplying means and to the dl/dt signal means for providing a fifth product signal corresponding to (dl/dt.( + or -sin theta ).sin phi ), and a third integrator integrates the fifth product signal to provide the Ao signal.