Monitoring matrix acidizing operations

Patent metadata

Field	Value
Publication number	US-2016146964-A1
Application number	US-201414550037-A
Country	US
Kind code	A1
Filing date	Nov 21, 2014
Priority date	Nov 21, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

An acoustic logging tool is disposed in a wellbore during an acidizing operation. Measurements are made using the acoustic logging tool on a region of a formation penetrated by the wellbore and being subjected to the acidizing operation. An acoustic anisotropic property of the formation is inferred at one or more depths of investigation within the region using the measurements, and a wormhole porosity and/or an orientation of one or more wormholes resulting from the acidizing operation is determined. Acidizing operation management decisions may be made based on the determined wormhole porosity and/or orientations of the wormholes. An acidizing operation management decision may be to maintain, increase, or decrease an acid injection rate. Measurements made may include the velocity of an acoustic wave propagating through the formation and the acoustic anisotropic properties of fast waves and slow waves. The acoustic anisotropic properties of the formation generally depend on rock stiffness.

First claim

What is claimed is:

1 . A method, comprising:
providing an acoustic logging tool and disposing the acoustic logging tool in a wellbore during an acidizing operation; making measurements using the acoustic logging tool on a region of a formation penetrated by the wellbore and being subjected to the acidizing operation; inferring one or more acoustic anisotropic properties of the formation at one or more depths of investigation within the region using the measurements; and determining a wormhole porosity and/or an orientation of one or more wormholes resulting from the acidizing operation based on the inferred one or more acoustic anisotropic properties.

2 . The method of claim 1 , further comprising:
making one or more acidizing operation management decisions based on the determined wormhole porosity and/or orientation of the one or more wormholes.

3 . The method of claim 2 , wherein the making one or more acidizing operation management decisions comprises:
maintaining an acid injection rate; increasing the acid injection rate; or decreasing the acid injection rate.

4 . The method of claim 1 , wherein the making measurements includes making in situ, real-time measurements.

5 . The method of claim 1 , wherein the making measurements includes measuring a velocity of acoustic wave propagation through the formation.

6 . The method of claim 5 , wherein the inferring one or more acoustic anisotropic properties uses the measured velocity of acoustic wave propagation.

7 . The method of claim 1 , wherein the making measurements includes measuring the acoustic anisotropic properties of fast waves and slow waves.

8 . The method of claim 1 , wherein the inferred one or more acoustic anisotropic properties of the formation depend on a rock stiffness.

9 . The method of claim 8 , wherein the rock stiffness is affected by presence of stress in the rock, presence of bed boundaries, presence of fractures, a compaction direction, and/or a compaction depth.

10 . The method of claim 9 , further comprising:
determining a maximum stress direction and/or a minimum stress direction in the formation.

11 . The method of claim 10 , further comprising:
determining a preferred fracture or wormhole direction based on the determined maximum stress direction and/or the minimum stress direction in the formation.

12 . The method of claim 9 , wherein the presence of stress and/or the presence of fractures are/is naturally occurring, induced, or both.

13 . The method of claim 1 , further comprising:
distinguishing between formations having fractures and formations having stress-induced anisotropy based on the frequency dependence of the one or more inferred acoustic anisotropic properties.

14 . The method of claim 1 , further comprising:
estimating a depth of wormhole penetration and a speed of wormhole penetration.

15 . The method of claim 1 , further comprising:
estimating optimal acidizing operating parameters for creating wormholes.

16 . The method of claim 1 , wherein the inferred acoustic anisotropic properties are selected from the group consisting of: slowness anisotropy, travel time anisotropy, and energy anisotropy.

17 . A system, comprising:
an acoustic logging tool disposed in a wellbore during an acidizing operation; and a processor located at the earth's surface or carried on the acoustic logging tool capable of: making measurements using the acoustic logging tool on a region of a formation penetrated by the wellbore and being subjected to the acidizing operation; inferring one or more acoustic anisotropic properties of the formation at one or more depths of investigation within the region using the measurements; and determining a wormhole porosity and/or an orientation of one or more wormholes resulting from the acidizing operation based on the inferred one or more acoustic anisotropic properties.

18 . The system of claim 17 , wherein the processor is further capable of making one or more acidizing operation management decisions based on the determined wormhole porosity and/or orientation of the one or more wormholes.

19 . The system of claim 18 , wherein the making one or more acidizing operation management decisions comprises: maintaining an acid injection rate; increasing the acid injection rate; or decreasing the acid injection rate.

20 . A non-transitory, computer-readable storage medium, which has stored therein one or more programs, the one or more programs comprising instructions, which when executed by a processor, cause the processor to perform a method comprising:
making measurements using an acoustic logging tool on a region of a formation penetrated by a wellbore and being subjected to an acidizing operation; inferring one or more acoustic anisotropic properties of the formation at one or more depths of investigation within the region using the measurements; and determining a wormhole porosity and/or an orientation of one or more wormholes resulting from the acidizing operation based on the inferred one or more acoustic anisotropic properties.

Assignees

• Schlumberger Technology Corp

Inventors

• Badri Mohammed
• Taherian Reza

Classifications

• E21B43/28

  Dissolving minerals other than hydrocarbons, e.g. by an alkaline or acid leaching agent (E21B43/241 takes precedence) · CPC title

• G01V2200/16

  Measure-while-drilling or logging-while-drilling · CPC title

• G01V1/50 Primary

  Analysing data · CPC title

• G01V2210/646

  Fractures · CPC title

• G01V2210/626

  with anisotropy · CPC title