Pumps-off annular pressure while drilling system

Patent metadata

Field	Value
Publication number	US-10125558-B2
Application number	US-201514710457-A
Country	US
Kind code	B2
Filing date	May 12, 2015
Priority date	May 13, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

Aspects of the disclosure can relate to a method for transmitting a pump-off pressure profile within a limited bandwidth. For example, a method may include selecting a compression protocol based upon at least one of a time length associated with the pump-off pressure data, a relative mean-squared error associated with the pump-off pressure data, or a maximum error associated with the pump-off pressure data. The method also includes compressing pump-off pressure data with the compression protocol to produce compression bits. The compression bits represent the pump-off pressure profile. The method also includes transmitting, via a communication module, the compression bits to a computing device.

First claim

What is claimed is:

1. A method for transmitting a pump-off pressure profile from a downhole tool located in a bottom hole assembly to a surface location, the method comprising:
causing the downhole tool to measure pump off pressure data in a subterranean wellbore;
preprocessing the pump off pressure data to define a pressure curve wherein the preprocessing includes removing data points from the pressure data that are greater than an upper threshold or less than a lower threshold;
selecting major points along the pressure curve such that an interpolation curve based on the major points approximates the pressure curve with an error less than an error threshold;
compressing the major points to generate a plurality of compression bits, the plurality of compression bits representing the major points and the pressure curve; and
causing a communications module located in the bottom hole assembly to transmit the plurality of compression bits from the bottom hole assembly to a computing device at the surface location;
wherein said preprocessing, said selecting major points, and said compressing is performed by a controller located in the bottom hole assembly.

2. The method of claim 1 , wherein said transmitting comprises transmitting the compression bits with a sequence of multiple on-demand frames.

3. The method of claim 2 , further comprising appending error correcting parity bits to at least one multiple on-demand frame of the sequence of multiple on-demand frames.

4. The method of claim 1 , further comprising appending data extension time data to the pump-off pressure data during at least one of a pumps-up transition period or a pumps-down transition period.

5. The method of claim 1 , wherein the pump-off pressure data comprises high density annular pressure while drilling data for leakoff testing (LOT).

6. The method of claim 1 , further comprising appending compressed extension pressure data to the plurality of compression bits, the compressed extension pressure data corresponding to at least one of a pump-down transition period or a pump-on transition period.

7. The method of claim 1 , wherein the preprocessing further comprises applying a uniform decimation to the pressure data if a time length associated with the pressure data exceeds a time threshold.

8. The method of claim 1 , wherein the error threshold comprises a first error threshold, a second error threshold, and a third error threshold that define errors between adjacent ones of the major points.

9. The method of claim 8 , wherein the first error threshold defines a maximum absolute error, the second error threshold defines a maximum distance and the third error threshold defines an absolute value of mean error between the interpolation curve and the pressure curve.

10. A system for transmitting a pump-off pressure profile to a surface location above a subterranean wellbore, the system comprising:
a downhole measurement tool configured to measure pump-off pressure data, the downhole measurement tool deployed in a bottom hole assembly which is in turn deployed in a subterranean wellbore;
the bottom hole assembly comprising a controller configured to (i) cause the downhole measurement tool to measure the pump-off pressure data; (ii) preprocess the pump off pressure data to define a pressure curve, wherein said preprocessing includes removing data points from the pressure data that are greater than an upper threshold or less than a lower threshold; (iii) select major points along the pressure curve such that an interpolation curve based on the major points approximates the pressure curve with an error less than an error threshold; and (iv) compress the major points to generate a plurality of compression bits, the plurality of compression bits representing the major points and the pressure curve; and
a communications module located in the bottom hole assembly and configured to transmit the plurality of compression bits from the bottom hole assembly to a computing device at the surface location.

11. The system of claim 10 , wherein the communication module is configured to transmit the compression bits with a sequence of multiple on-demand frames.

12. The system of claim 11 , wherein the controller is configured to append error correcting parity bits to at least one multiple on-demand frame of the sequence of multiple on-demand frames.

13. The system of claim 10 , wherein the controller is further configured to append data extension time data to the pump-off pressure data during at least one of a pumps-up transition period or a pumps-down transition period.

14. The system of claim 10 , wherein the pump-off pressure data comprises high density annular pressure while drilling data for leakoff testing (LOT).

15. The system of claim 10 , wherein the communication module comprises a plurality of valves, wherein the controller is further configured to cause the plurality of valves to modulate a flow of drilling fluid, the modulated drilling fluid representing the plurality of compression bits.

16. The system of claim 10 , wherein said preprocessing further comprises applying a uniform decimation to the pressure data if a time length associated with the pressure data exceeds a time threshold.

17. The method of claim 10 , wherein the error threshold comprises a first error threshold, a second error threshold, and a third error threshold that define errors between adjacent ones of the major points.

18. The method of claim 17 , wherein the first error threshold defines a maximum absolute error, the second error threshold defines a maximum distance and the third error threshold defines an absolute value of mean error between the interpolation curve and the pressure curve.

Assignees

• Schlumberger Technology Corp

Inventors

• Sun Yong
• Yu Bo
• Reyes Sandra
• Garcia-Mayans Aldrick

Classifications

• E21B47/12

  Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling · CPC title

• E21B21/08 Primary

  Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure (valve arrangements therefor E21B21/10) · CPC title

• G05B15/02

  electric · CPC title

• E21B47/06

  Measuring temperature or pressure · CPC title

• E21B21/10

  Valve arrangements in drilling-fluid circulation systems · CPC title