Method of predicting geothermal gradients in wells

• US 4,008,608 A
• Filed: 10/10/1974
• Issued: 02/22/1977
• Est. Priority Date: 10/10/1974
• Status: Expired due to Term

• Current Assignee: Continental Oil Company (ConocoPhillips)
• Original Assignee: Continental Oil Company (ConocoPhillips)
• Inventors: Reynolds, Edward B.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/513,791
• Time in Patent Office: 866 Days
• Field of Search: 73/154, 73/152, 181/102, 181/105
• US Class Current: 73/152.12
• CPC Class Codes: E21B 47/07 Temperature
• CPC Class Codes: G01K 11/24 of the velocity of propagation of sound
• CPC Class Codes: G01V 1/00 Seismology; Seismic or acoustic prospecting or detecting
• CPC Class Codes: G01V 9/005 by thermal methods, e.g. after generation of heat by chemical reactions

Abstract

Method of predicting geothermal gradients of subterranean strata comprising relating trends or changes in the velocity of waves propagated through the strata with similar trends or changes in strata whose geothermal gradient is known.

Claims

1. A method of predicting the geothermal gradient of subterranean strata by determining velocity trends in the strata and comparing same with the velocity trends of formations for which geothermal gradients have previously been determined and plotted on semi-logarithmic paper as a family of curves of velocity trends versus geothermal gradients comprising:

a. determining the velocity trend at various depths of a wave propagated through the subterranean strata,

b. plotting the velocity trend versus depth on semi-logarithmic paper to generate a curve, and

c. comparing the curve obtained with a family of similar curves of known geothermal gradients.

2. The method of claim 1 wherein the velocity trend is a check shot velocity survey trend.

3. The method of claim 1 wherein the velocity trend is an acoustic log trend.

4. The method of claim 1 wherein the velocity trend is a seismic velocity trend.

5. The method of claim 1 wherein the velocity trend is established from the surface of the earth.

6. The method of claim 1 wherein the velocity trend is established from a borehole drilled at least partially through the subterranean strata.

7. The method of claim 1 wherein the wave propagated through the subterranean strata is a sound wave or a shock wave.

8. A method of predicting the geothermal gradient of subterranean strata from the surface of the earth by determining velocity trends in the strata and comparing same with the velocity trends of formations for which geothermal gradients have previously been determined and plotted on semi-logarithmic paper as a family of curves of velocity trends versus geothermal gradients comprising:

a. running a seismic velocity analysis on the subterranean strata,

b. plotting the results of the seismic velocity analysis versus depth on semi-logarithmic paper, and

c. comparing the plot obtained with similar plots of known geothermal gradient.

9. A method of predicting the geothermal gradient of subterranean strata from a borehole by determining velocity trends in the strata and comparing same with the velocity trends of formations for which geothermal gradients have previously been determined and plotted on semi-logarithmic paper as a family of curves of velocity trends versus geothermal gradients comprising:

a. running an acoustic log in the borehole,

b. plotting the results of the acoustic log versus depth on semi-logarithmic paper, and

c. comparing the plot obtained with similar plots of known geothermal gradient.

10. A method of predicting the geothermal gradient of subterranean strata from a borehole by determining velocity trends in the strata and comparing same with the velocity trends of formations for which geothermal gradients have previously been determined and plotted on semi-logarithmic paper as a family of curves of velocity trends versus geothermal gradients comprising:

a. running a check shot velocity survey in the borehole,

b. plotting the results of the velocity survey versus depth on semi-logarithmic paper, and

c. comparing the plot obtained with similar plots of known geothermal gradient.