Cuttings analysis for improved downhole NMR characterisation

Patent metadata

Field	Value
Publication number	US-10436865-B2
Application number	US-201615543576-A
Country	US
Kind code	B2
Filing date	Jan 15, 2016
Priority date	Jan 16, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A method for combining nuclear magnetic resonance (NMR) analysis and digital rock physics (DRP) analysis based on drilling cuttings or other rock samples for improved downhole nuclear magnetic resonance validation and characterization. A system for performing the method also is provided.

First claim

What is claimed is:

1. A method for validating subterranean rock properties of a rock formation estimated by nuclear magnetic resonance, comprising
a) retrieving rock samples from drill cuttings within a used drilling fluid from a defined location inside a well during drilling;
b) scanning the rock samples to produce digital images of the rock samples;
c) segmenting the digital images to provide segmented digital images, wherein pores, grains, and organic content are defined in the segmented digital images;
d) determining rock property for at least one of the rock samples using the segmented digital images;
e) performing nuclear magnetic resonance (NMR) logging of the well with an NMR logging tool during the drilling or after the drilling;
f) measuring in situ fluid properties and in situ well properties in the well using the NMR logging tool;
g) estimating a rock property in the well at the defined location using the measured in situ well properties obtained in step f);
h) comparing the estimated rock property for the defined location with the determined rock property for the defined location; and
i) analysing and validating the estimated rock property for the defined location inside the well.

2. The method of claim 1 , wherein step a) comprises:
i) extracting additional drill cuttings from the used drilling fluid at the Earth's surface, wherein the drilling fluid transports the drill cuttings to the Earth's surface after use of the drilling fluid in the drilling;
ii) grouping the drill cuttings into a group of cuttings based on a time of arrival of the drill cuttings at the Earth's surface;
iii) repeating steps i) and ii) at least once to provide a plurality of groups of drill cuttings that arrive sequentially at different recorded times at the Earth's surface which are correlated with a location within the well.

3. The method of claim 2 , wherein ii) comprises estimating downhole coordinates from which the group of cuttings were produced to within about plus or minus 10 feet of actual downhole location.

4. The method of claim 2 , wherein the extracting of the drill cuttings from the drilling fluid in i) comprises separating the cuttings from the drilling fluid with a shale shaker.

5. The method of claim 1 , wherein two or more groups of drill cuttings are analyzed in d), e), f) and g), wherein corresponding downhole coordinates of estimated locations of each of two or more groups of drill cuttings is recorded along with the physical location of the groups of drill cuttings.

6. The method of claim 1 , wherein the scanning in step b) of the rock samples is done using X-ray computer tomographic scanning or scanning electron spectroscopy to produce the digital images of the rock samples.

7. The method of claim 1 , wherein the well bore is vertically-oriented relative to Earth's surface and further comprising measuring paramagnetic content of the rock samples using laser induced breakdown spectroscopy (LIBS) or X-ray fluorescence (XRF) measurements.

8. The method of claim 1 , wherein the well bore is horizontally-oriented relative to Earth's surface.

9. The method of claim 1 , wherein the NMR logging tool is passed through the well bore using a logging wire or measurement/logging while drilling (M/LWD).

10. The method of claim 1 , wherein the NMR logging tool is used in combination with a density logging tool.

11. The method of claim 1 wherein the fluid properties comprise temperature, pressure, viscosity, hydrogen index, chemical composition, or any combinations thereof.

12. The method of claim 1 , wherein the in situ well properties comprise T1 and T2 relaxation times from NMR, diffusion measurements, T1-T2 correlations, T2-diffusion correlations, T1-diffusion correlation, hydrogen index, temperature, pressure, resistivity, gamma, neutron-density, downhole images, well bore gauge, or any combinations thereof.

13. The method of claim 1 , wherein the rock properties comprise total porosity, effective porosity, removable (free) water volume, bound water volume, pore size distribution, connected porosity, absolute permeability, relative permeability, capillary pressure, m and n Archies constants, elastic moduli, electrical properties, or any combinations thereof.

14. A system for validating subterranean rock properties of a rock formation estimated by nuclear magnetic resonance, comprising
(a) a drill cutting collection unit for extracting drill cuttings from a drilling fluid in groups of drill cuttings based on a time of arrival of the drill cuttings at the Earth's surface and placing the groups of drill cuttings in respective containers;
(b) a SEM, FIB-SEM, or X-ray CT scanner having a stage capable of holding at least one of the groups of drill cuttings, operable to produce digital images of at least one or more of the drill cuttings, and operable to output the digital images to at least one computer;
(c) a NMR logging tool positionable inside a well borehole and operable for measuring in situ fluid and well properties in at least one well interval in a well, and operable to output acquired data to the at least one computer;
(d) the at least one computer comprising at least one computer processor programmable for (i) segmenting the digital images of the drill cuttings to define pores, grains and organic content in the digital image, (ii) determining at least one rock property of the rock samples using the segmented digital images; (iii) estimating at least one rock property in the well at one or more locations using measured in situ well properties obtained using the NMR logging tool; (iv) comparing the determined rock property with the estimated rock properly for a corresponding at least one of the one or more locations of the well; and (v) analysing and validating the estimated rock property for the corresponding at least one of the one or more locations of the well, and vi) outputting the results to at least one device to display, print, or store results of the computations; and
(e) at least one device to display, print, or store results of one or more computations of step (d).

15. A non-transitory computer readable medium comprising instructions that, when performed by a processor perform a method for:
c) segmenting the digital images to provide segmented digital images, wherein pores, grains, and organic content are defined in the segmented digital images;
d) determining a rock property for at least one of the rock samples taken from a defined location inside the well using the segmented digital images;
f) measuring in situ fluid properties and in situ well properties in the well using the NMR logging tool at the multiple locations;
g) estimating the rock property in the well at the defined location using the measured in situ well properties obtained in step f);
h) comparing the estimated rock property for the defined location with the rock property determined for the defined location; and
i) analysing and validating the at least one rock property determined using the NMR logging tool as compared to the at least one rock property determined for the rock samples for the corresponding at least one of the one or more locations of the well.

Assignees

• Ingrain Inc
• Halliburton Energy Services Inc

Inventors

• Washburn Kathryn Elizabeth

Classifications

• G01N23/046

  using tomography, e.g. computed tomography [CT] · CPC title

• G01V3/32

  operating with electron or nuclear magnetic resonance · CPC title

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• G01R33/44

  using nuclear magnetic resonance [NMR] (G01R33/24, G01R33/62 take precedence) · CPC title

• G01R33/4808 Primary

  Multimodal MR, e.g. MR combined with positron emission tomography [PET], MR combined with ultrasound or MR combined with computed tomography [CT] · CPC title