# US 8,783,381 B2 · Formation testing in managed pressure drilling

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- Number: US 8,783,381 B2
- Document ID: US8783381B2
- Status: Granted
- Kind: B2
- Application number: 13/546,117
- Filed: 2012-07-11
- Published: 2013-01-17
- Granted: 2014-07-22
- Earliest claimed: 2011-07-12
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Stuart M. Jeffries
- Inventors: Stuart M. Jeffries
- Web page: https://patentgrep.com/patent/US8783381B2

## CPC

- E21B 49/00: Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B 21/08: 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)
- E21B 49/003: {by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00)}
- E21B 49/08: Obtaining fluid samples or testing fluids, in boreholes or wells
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A method of testing an earth formation can include incrementally opening a choke while drilling into the formation is ceased, thereby reducing pressure in a wellbore, and detecting an influx into the wellbore due to the reducing pressure in the wellbore. Another method of testing an earth formation can include drilling into the formation, with an annulus between a drill string and a wellbore being pressure isolated from atmosphere, then incrementally opening a choke while drilling is ceased, thereby reducing pressure in the wellbore, detecting an influx into the wellbore due to the reducing pressure in the wellbore, and determining approximate formation pore pressure as pressure in the wellbore when the influx is detected. Drilling fluid may or may not flow through the drill string when the influx is detected. A downhole pressure sensor can be used to verify pressure in the wellbore.

## Claims

### Claim 1

A method of testing an earth formation, the method comprising:
drilling a wellbore into the formation;
circulating drilling fluid into the wellbore;
then ceasing drilling the wellbore and ceasing circulation of the drilling fluid;
then incrementally opening a choke while drilling the wellbore is ceased and while circulation of the drilling fluid into the wellbore is ceased, thereby reducing pressure in the wellbore; and
detecting an influx into the wellbore due to the reducing pressure in the wellbore.

### Claim 2 (depends on 1)

The method of claim 1, further comprising resuming circulation of the drilling fluid into the wellbore; and
then verifying the pressure in the wellbore with at least one pressure sensor in the wellbore.

### Claim 3

A method of testing an earth formation, the method comprising:
drilling into the formation, with an annulus between a drill string and a wellbore being pressure isolated from atmosphere;
ceasing circulation of drilling fluid into the wellbore;
then incrementally opening a choke, thereby reducing pressure in the wellbore;
then detecting an influx into the wellbore due to the reduced pressure in the wellbore while circulation is ceased; and
determining approximate formation pore pressure as pressure in the wellbore when the influx is detected.

### Claim 4 (depends on 3)

The method of claim 3, wherein incrementally opening the choke is performed multiple times.

### Claim 5 (depends on 4)

The method of claim 4, wherein incrementally opening the choke ceases when the influx is detected.

### Claim 6 (depends on 3)

The method of claim 3, further comprising resuming circulation of the drilling fluid into the wellbore; and
then verifying the pressure in the wellbore with at least one pressure sensor in the wellbore.

### Claim 7 (depends on 3)

The method of claim 3, further comprising verifying the pressure in the wellbore with at least one pressure sensor in the wellbore.

### Claim 8 (depends on 3)

The method of claim 3, wherein detecting an influx comprises detecting how fluid flows out of the wellbore.

### Claim 9 (depends on 3)

The method of claim 3, wherein determining approximate formation pore pressure comprises summing pressure in the annulus near the surface with hydrostatic pressure in the wellbore.

### Claim 10

A method of testing an earth formation, the method comprising:
drilling into the formation, with an annulus between a drill string and a wellbore being pressure isolated from atmosphere;
circulating drilling fluid into the wellbore;
then ceasing drilling the wellbore and ceasing circulation of drilling fluid into the wellbore;
then incrementally opening a choke while drilling is ceased, thereby reducing pressure in the wellbore;
detecting an influx into the wellbore due to the reducing pressure in the wellbore; and
determining approximate formation pore pressure as pressure in the wellbore when the influx is detected.

### Claim 11 (depends on 10)

The method of claim 10, further comprising resuming circulation of the drilling fluid into the wellbore; and
then verifying the pressure in the wellbore with at least one pressure sensor in the wellbore.