Log processing and fracture characterization in biaxially anisotropic formations

Patent metadata

Field	Value
Publication number	US-10400589-B2
Application number	US-201514779196-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	Apr 18, 2014
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

Evaluation of formation and fracture characteristics based on multicomponent induction (MCI) log data includes automated calculation of inverted biaxial anisotropy (BA) parameters for the formation by performing an iterative BA inversion operation based on the MCI log data and using a BA formation model that accounts for transfers by axial formation anisotropy to resistivity. The BA inversion operation can be combined with a transversely anisotropic (TI) inversion based on the MCI log data and using a TI formation model, to calculate inverted TI parameters for the formation. The inverted BA parameters and the inverted TI parameters can be used, in combination, to calculate a quantified value for an identification function, to indicate estimated presence or absence of a fracture in the formation.

First claim

What is claimed is:

1. A method comprising:
lowering a multicomponent induction (MCI) measurement tool into a borehole extending through a subsurface formation, wherein the MCI measurement tool comprises a subarray comprising a mutually orthogonal receiver triad, and wherein the mutually orthogonal receiver triad comprises a first receiver at a first axis, a second receiver at a second axis, and a third receiver at a third axis;
producing MCI measurement data that comprises a first voltage measurement from the first receiver, a second voltage measurement from the second receiver, and a third voltage measurement from the third receiver, and wherein each voltage measurement is produced by the MCI measurement tool while the MCI measurement tool is operated at one or more frequencies;
calculating inverted biaxial anisotropy (BA) parameters by performing an iterative BA inversion operation based on at least the first voltage measurement, the second voltage measurement, and the third voltage measurement using a BA formation model that accounts for resistivity anisotropy between a first formation principal axis and a second formation principal axis that is orthogonal to the first formation principal axis and resistivity anisotropy between a substantially vertical formation principal axis and the first formation principal axis, wherein the substantially vertical formation principal axis is orthogonal to the first and second formation principal axes;
calculating inverted transverse isotropy (TI) parameters by performing an iterative TI inversion operation based on the MCI measurement data using a TI formation model that accounts for resistivity isotropy between the first formation principal axis and the second formation principal axis and resistivity anisotropy between the substantially vertical formation principal axis and the first formation principal axis; and
indicating at least one of a fracture property and a fracture presence based on a difference between a formation parameter determined from one or more of the inverted BA parameters and a formation parameter determined from one or more of the inverted TI parameters.

2. The method of claim 1 , wherein producing the MCI measurement data comprises capturing the MCI measurement data while the subarray of the MCI measurement tool is operated at a single-frequency.

3. The method of claim 1 , wherein the BA formation model is a radially one-dimensional model (R1D-BA), wherein the radially one-dimensional model comprises a borehole model as a circular cross-section surrounded by a formation, accounting for biaxial anisotropy to resistivity.

4. The method of claim 3 , further comprising performing a second BA inversion operation based at least in part on the MCI measurement data and using a second BA formation model.

5. The method of claim 4 , wherein the second BA formation model is a vertically one-dimensional model (V1D-BA) accounting for biaxial anisotropy to resistivity, the method further comprising calculating shoulder-corrected formation parameters based on performance of the second BA inversion operation.

6. The method of claim 1 , wherein the BA formation model is a two-dimensional model (2D-BA) accounting for biaxial anisotropy to resistivity.

7. The method of claim 1 , wherein the TI formation model is a radially one-dimensional model (R1D-TI), wherein the radially one-dimensional model comprises a borehole model as a circular cross-section surrounded by a formation, that accounts for transverse isotropy to resistivity.

8. The method of claim 7 , further comprising calculating, based at least in part on the inverted TI parameters, MCI borehole corrected measurement data by processing the MCI measurement data to correct for borehole effects.

9. The method of claim 7 , wherein the BA formation model is a vertically one-dimensional model that accounts for biaxial anisotropy to resistivity (V1D-BA), the performing of the BA inversion operation based at least in part on the inverted TI parameters.

10. The method of claim 7 , where the BA formation model is a zero dimensional model that accounts for biaxial formation anisotropy (0D-BA), the 0D-BA assuming a homogenous unbounded formation which is biaxially anisotropic in resistivity.

11. The method of claim 1 , wherein indicating at least one of the fracture property and the fracture presence comprises calculating a value of an identification function based on at least some formation parameters calculated based on the MCI measurement data, the identification function being variable as a function of one or more of the inverted BA parameters and one or more of the inverted TI parameters.

12. The method of claim 1 , wherein the inverted BA parameters comprise a residual error when a BA medium is assumed during inversion and the inverted TI parameters is a residual error when a TI medium is assumed during inversion.

13. The method of claim 1 , further comprising calculating a ratio between a summed value and a difference value, wherein the summed value is the sum of a first log response and second log response that is orthogonal to the first log response, and the difference value is the difference of the first log response and the second log response.

14. The method of claim 1 , wherein the BA inversion operation and the TI inversion operation comprises:
a radially one-dimensional inversion based on formation transverse isotropy (R1D-TI), wherein the R1D-TI comprises modeling the borehole as a circular cross-section surrounded by a formation, and a zero dimensional inversion based on formation biaxial anisotropy (0D-BA); or
a R1D-TI inversion and a vertically one-dimensional inversion based on formation biaxial anisotropy (V1D-BA).

15. The method of claim 1 , wherein the MCI measurement tool comprises three mutually orthogonal collocated antennas, and wherein the MCI measurement data comprises a first electromagnetic property along the first formation principal axis, a second electromagnetic property along the second formation principal axis, and a third electromagnetic property along the substantially vertical formation principal axis.

16. The method of claim 1 , wherein the formation parameter determined from the one or more of the inverted BA parameters is a first dip angle, and wherein the formation parameter determined from the one or more of the inverted TI parameters is a second dip angle.

17. A system comprising:
a multicomponent induction (MCI) measurement tool that comprises a subarray comprising a mutually orthogonal receiver triad, wherein the mutually orthogonal receiver triad comprises a first receiver at a first axis, a second receiver at a second axis, and a third receiver at a third axis;
at least one of a main memory or a static memory to store MCI measurement data captured by the MCI measurement tool in a borehole extending through a subsurface formation, wherein the MCI measurement data comprises a first voltage measurement from the first receiver, a second voltage measurement from the second receiver, and a third voltage measurement from the third receiver, and wherein each voltage measurement is produced by the MCI measurement tool while the MCI measurement tool is operated at one or more frequencies; and
a non-transitory machine-readable storage device having instructions that are executable by one or more processors to cause the one or more processors to:
calculate inverted biaxial anisotropy (BA) parameters by performing an iterative BA inversion operation based on at least the first voltage measurement, the second voltage measurement, and the third voltage measuremen

Assignees

• Halliburton Energy Services Inc

Inventors

• Hou Junsheng
• Donderici Burkay
• Wu Dagang

Classifications

• E21B19/22

  Handling reeled pipe or rod units, e.g. flexible drilling pipes {(lifting or hauling appliances using two or more cooperating endless chains B66D3/003)} · CPC title

• E21B47/12 Primary

  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

• E21B49/00 Primary

  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 · CPC title

• G01V3/38

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title

• G01V3/28

  using induction coils · CPC title