Claims
- 1. A method for compressing data gathered in a wellbore, the method comprising:
(a) acquiring a plurality of wellbore values; and (b) applying a curve fit analysis to the wellbore values.
- 2. The method according to claim 1 further comprising:
(c) determining curve fit parameters from the curve fit analysis.
- 3. The method according to claim 2 further comprising:
(d) generating an error function by comparing the curve fit analysis to the wellbore values.
- 4. The method according to claim 3 further comprising:
(e) transmitting the curve fit parameters, the error function, and a predetermined number of the wellbore values to the surface of the wellbore, wherein the predetermined number of the wellbore values is less than the plurality of pressure values.
- 5. The method according to claim 4 further comprising:
(f) creating a data curve at the surface of the wellbore based on the curve fit parameters, the error function, and the predetermined number of the wellbore values.
- 6. A method of compressing pressure data gathered in a wellbore, the method comprising:
(a) acquiring a plurality of pressure values; (b) generating at least one pressure curve from the pressure values; and (c) expressing one of the pressure curves in terms of a mathematical equation.
- 7. The method according to claim 6 wherein the pressure curve comprises a drawdown pressure curve Pdd(t) according to the following mathematical equation:
- 8. The method according to claim 7 wherein the curve fit parameters α, β and Pf are defined by comparing the mathematical equation Pdd(t) to the plurality of pressure values.
- 9. The method according to claim 6 further comprising:
(d) defining at least one curve fit parameter by comparing the mathematical equation to the plurality of pressure values.
- 10. The method according to claim 9 further comprising:
(e) measuring the correlation between the plurality of pressure values and the mathematical equation in terms of an error function.
- 11. The method according to claim 10 wherein the step e) further comprises the sub-steps of:
(i) approximating the solution of the mathematical equation using the curve fit parameters; and (ii) comparing the approximated solution to the plurality pressure values.
- 12. The method according to claim 11 wherein the error function comprises a chi-squared (X2) value.
- 13. The method according to claim 10 further comprising:
(f) transmitting the at least one curve fit parameter, the error function, and a predetermined number of the pressure values to the surface of the wellbore, wherein the predetermined number of the pressure values is less than the plurality of pressure values; and (g) creating a pressure curve at the surface of the wellbore based on the at least one curve fit parameter, the error function, and the predetermined number of the pressure values.
- 14. The method according to claim 6 further comprising:
(d) expressing a second pressure curve in terms of a second mathematical equation.
- 15. The method according to claim 14 wherein the second pressure curve comprises a buildup pressure curve Pbu(t) according to the following second mathematical equation:
- 16. The method according to claim 15 wherein the curve fit parameters α, β and Pf are defined by comparing the mathematical equation Pbu(t) to the plurality of pressure values.
- 17. The method according to claim 14 further comprising:
(e) defining at least one curve fit parameter by comparing the second mathematical equation to the plurality of pressure values.
- 18. The method according to claim 17 further comprising:
(f) measuring the correlation between the plurality of pressure values and the second mathematical equation in terms of an error function.
- 19. The method according to claim 18 wherein step (f) further comprises the sub-steps of:
(i) approximating the solution of the second mathematical equation using the curve fit parameters; and (ii) comparing the approximated solution to the plurality of pressure values.
- 20. The method according to claim 19 wherein the error function comprises a chi-squared (X2) value.
- 21. The method according to claim 18 further comprising:
(f) transmitting the at least one curve fit parameter, the error function, and a predetermined number of the pressure values to the surface of the wellbore, wherein the predetermined number of the pressure values is less than the plurality of pressure values; and (g) creating a second pressure curve at the surface of the wellbore based on the at least one curve fit parameter, the error function, and the predetermined number of the pressure values.
- 22. The method according to claim 6 wherein at least one of the pressure values is selected from the group consisting of Phyd1, Pdd, Pfu, Pstop, and Phyd2.
- 23. The method according to claim 22 wherein at least five pressure values are acquired comprising Phyd1, Pdd, Pfu, Pstop, and Phyd2.
- 24. A control assembly for use in a formation test while drilling apparatus located in a wellbore, the control assembly comprising:
a pressure sensor for detecting a quantity of formation pressure data; a control module coupled to the pressure sensor, the control module configured to reduce the quantity of data received from the pressure sensor and transmit the reduced quantity of pressure data to the surface of the wellbore.
- 25. The control assembly according to claim 24 wherein the control module further comprises:
a memory device having embedded compression software code; and a processor configured to perform a curve fit analysis to the quantity of data using the software code.
- 26. The control assembly according to claim 25 wherein the memory device is configured to store the quantity of formation pressure data.
- 27. The control assembly according to claim 26 wherein the software code and formation pressure data are stored in separate memory devices.
- 28. The control assembly according to claim 25 wherein the software code comprises:
a first equation 4Pdd(t)=Pdd-(β+Pdd-Pf1-ⅇ-Δ tα)(1-ⅇ-tα), wherein t is time and α, β and Pf are curve fit parameters; and a second equation 5Pbu(t)=Pf-β ⅇ-t′α, wherein t′ is a second time value.
- 29. The control assembly according to claim 28 wherein the curve fit analysis is configured to generate curve fit parameters α, β and Pf by comparing the equations Pdd(t) and Pbp(t) to the quantity of formation pressure data.
- 30. The control assembly according to claim 29 wherein the processor is further configured to generate a correlation measurement by approximating solutions to the equations Pdd(t) and Pbp(t) using the generated curve fit parameters α, β and Pf and comparing the approximated solutions to the quantity of formation pressure data.
- 31. The control assembly according to claim 30 wherein the correlation measurement is represented by an error function.
- 32. The control assembly according to claim 31 wherein the error function is a chi-squared (X2) value.
- 33. A formation test while drilling apparatus for gathering formation pressure data and sending the data to the surface of a wellbore, the apparatus comprising:
a longitudinal body configured to be coupled to a drill string; a formation testing assembly coupled to the body; a transmitter device coupled to the body; a pressure sensor for gathering a quantity of formation pressure data; and a control module comprising:
a first memory device for storing software code; a second memory device for storing the quantity of formation pressure data; and a processor configured to use the software code to compress the quantity of pressure data transmitted to the surface of the wellbore.
- 34. The formation test while drilling apparatus according to claim 33 wherein the quantity of formation pressure data can be represented by a plurality of pressure curves.
- 35. The formation test while drilling apparatus according to claim 34 wherein the software code includes a curve fit analysis, and wherein the processor applies the curve fit analysis to the plurality of pressure curves.
- 36. The formation test while drilling apparatus according to claim 35 wherein application of the curve fit analysis yields a plurality of curve fit parameters and an error function.
- 37. The formation test while drilling apparatus according to claim 36 wherein the transmitter device transmits the plurality of curve fit parameters, the error function, and a predetermined number of the pressure data values to the surface of the wellbore, wherein the predetermined number of the pressure data values is less than the quantity of formation pressure data.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S. Provisional Application Serial No. 60/381,347, filed May 17, 2002, entitled Formation Testing While Drilling Data Compression, which is hereby incorporated herein by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60381347 |
May 2002 |
US |