CLEANUP PRODUCTION DURING SAMPLING

• US 20100294491A1
• Filed: 11/10/2008
• Published: 11/25/2010
• Est. Priority Date: 11/16/2007
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Canada Limited (Schlumberger NV)
• Inventors: Zazovsky, Alexander F.
• Granted Patent: US 8,744,774 B2
• Time in Patent Office: Days
• US Class Current: 166/250.01
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: E21B 49/087 Well testing, e.g. testing for reservoir productivity or formation parameters

Abstract

Cleanup monitoring and prediction in real time targeting estimation of pumpout volume versus final contamination, including detecting breakthrough of formation fluid to a sampling tool and detecting transition of cleanup regime from a predominantly circumferential cleanup regime to a predominantly vertical cleanup regime. Similar workflow can be employed for estimating contamination at the end of cleanup production for a given pumpout volume.

Claims

1. A method of formation evaluation, comprising:

lowering a sampling tool into a wellbore penetration a subterranean formation;

establishing fluid communication with the formation;

estimating a depth of invasion;

selecting a cleanup model based on the estimated invasion; and

using the cleanup model to determine a sample fluid related parameter.

2. The method of claim 1 wherein estimating the depth of invasion includes detecting a breakthrough volume.

3. The method of claim 1 wherein the sample fluid related parameter is at least one of a contamination level and a pump out volume to achieve a contamination target.

4. The method of claim 1 wherein selecting the cleanup model based on the estimated invasion includes selecting between a substantially circumferential cleanup model and a substantially vertical cleanup model.

5. The method of claim 1 wherein selecting the cleanup model based on the estimated invasion includes detecting a transition from a substantially circumferential cleanup regime to a substantially vertical cleanup regime.

6. The method of claim 1 wherein using the cleanup model to determine the sample fluid related parameter includes modifying the estimated depth of invasion.

7. A method of formation evaluation, comprising:

lowering a sampling tool into a wellbore penetration a subterranean formation;

establishing fluid communication between the formation and a sample tool;

detecting breakthrough of formation fluid to the sampling tool; and

detecting transition of cleanup regime from a predominantly circumferential cleanup regime to a predominantly vertical cleanup regime.

8. The method of claim 7 further comprising characterizing flow and contamination transport patterns in the formation based on the breakthrough detection and the transition detection.

9. The method of claim 8 further comprising estimating an initial depth of invasion prior to detecting the breakthrough and the transition.

10. The method of claim 9 wherein estimating an initial depth of invasion is performed in the absence of viscosity contrast.

11. The method of claim 9 further comprising reconstructing the initial depth of invasion after detecting the breakthrough and the transition based on the detected breakthrough and transition.

12. The method of claim 11 wherein reconstructing the initial depth of invasion is performed in the absence of viscosity contrast.

13. A method of cleanup monitoring and prediction in real time targeting estimation of pumpout volume versus final contamination, comprising:

determining a breakthrough production volume;

detecting a first production volume corresponding to transition of a first cleanup regime to a second cleanup regime;

determining a first normalized production volume corresponding to the cleanup regime transition, wherein determining the first normalized production volume is based on the breakthrough production volume and the first production volume;

determining a first invasion depth estimate corresponding to the first normalized production volume;

determining a second normalized production volume corresponding to a predetermined contamination target, wherein determining the second normalized production volume is based on the estimated first invasion depth; and

determining a second production volume corresponding to the contamination target, wherein determining the second production volume is based on the second normalized production volume and the breakthrough production volume.

14. The method of claim 13 wherein the first cleanup regime is a predominantly circumferential regime and the second cleanup regime is a predominantly vertical regime.

15. The method of claim 13 wherein determining the first invasion depth estimate corresponding to the first normalized production volume includes determining a logarithmic relation between the first normalized production volume and the ratio of invasion depth to wellbore radius.