# US 10,481,291 B2 · Chemically-selective imager for imaging fluid of a subsurface formation and method of using same

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- Number: US 10,481,291 B2
- Document ID: US10481291B2
- Status: Granted
- Kind: B2
- Application number: 15/448,183
- Filed: 2017-03-02
- Published: 2017-09-07
- Granted: 2019-11-19
- Earliest claimed: 2016-03-03
- Assignees: Shell Oil Company
- Applicants: Shell Oil Company
- Inventors: Matthias Appel; Benjamin Charles Anger; Hilko de Jong; Lynn Faith Gladden; Michael David Mantle; Andrew John Sederman; Nicholas Philip Ramskill
- Web page: https://patentgrep.com/patent/US10481291B2

## CPC

- G01V 3/32: operating with electron or nuclear magnetic resonance
- E21B 47/0025: {generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric}
- E21B 49/06: using side-wall drilling tools {pressing} or scrapers
- E21B 49/10: using side-wall fluid samplers or testers
- G01N 24/081: {Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity}
- G01R 33/4828: {Resolving the MR signals of different chemical species, e.g. water-fat imaging}
- G01R 33/561: by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
- G01R 33/5611: {Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE (structural details of arrays of sub-coils G01R33/3415)}
- G01R 33/5617: {using RF refocusing, e.g. RARE}
- E21B 47/06: Measuring temperature or pressure
- E21B 47/07: Temperature
- Y02A 90/30: Assessment of water resources
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

An imager and method for imaging fluid of a subsurface formation is disclosed. The imager includes a housing having a sidewall defining a passage to receive a core sample of the subsurface formation therethrough. The housing is positioned in a downhole tool and has a fluid inlet to receive fluid from the subsurface formation into the passage. The imager also includes a permanent magnet positioned in the sidewall of the housing, a radio frequency coil positioned in the sidewall of the housing between the permanent magnet and the passage, a gradient field in the sidewall of the housing between the permanent magnet and the radio frequency coil, and a chemically-selective imager. The chemically-selective imager is operatively connected to the radio frequency coil to selectively pulse frequencies according to a pulse sequence whereby individual fluid measurements of the sample are generated.

## Claims

### Claim 1

An imager for imaging fluid of a subsurface formation, the imager comprising:
a housing having a sidewall defining a passage to receive a core sample of the subsurface formation therethrough, the housing positioned in a downhole tool, the housing having a fluid inlet to receive fluid from the subsurface formation into the passage;
a permanent magnet positioned in the sidewall of the housing, the permanent magnet comprising magnetic coils oriented to direct a magnetic field through the passage;
a radio frequency coil positioned in the sidewall of the housing between the permanent magnet and the passage, the radio frequency coil oriented to direct a radio frequency field through the passage;
a magnetic field gradient positioned in the sidewall of the housing between the permanent magnet and the radio frequency coil to selectively direct a gradient field through the passage; and
a chemically-selective imager configured to generate images of the fluid in the core sample operatively connected to the radio frequency coil to selectively pulse frequencies according to a pulse sequence whereby images of hydrocarbons and aqueous fluids in the core sample are generated based on differences in chemical shift, wherein nuclear magnetic resonance measurement is performed using compressed sensing and rapid acquisition with relaxation enhancement (RARE).

### Claim 2 (depends on 1)

The imager of claim 1, wherein the radio frequency coil is distributed radially about the passage and oriented to direct the radio frequency field in a direction orthogonal to the longitudinal axis of the passage.

### Claim 3 (depends on 1)

The imager of claim 1, wherein the pulse frequencies are one of 1D, 2D and 3D pulse frequencies.

### Claim 4 (depends on 1)

The imager of claim 1, wherein the passage has an outlet to pass the core sample and the formation fluid from the passage.

### Claim 5 (depends on 1)

The imager of claim 1, further comprising a passage inlet located in the housing disposed to receive the core sample into the passage.

### Claim 6 (depends on 1)

The imager of claim 1, further comprising an imaging unit operatively connected to the imager, the imaging unit being configured to display an image of the fluid in the core sample.

### Claim 7

A method of imaging fluid positioned in a subsurface formation, the method comprising:
positioning a core sample of the subsurface formation in a passage of an imager in a downhole tool;
flooding the core sample by passing fluid from the formation into the passage;
imaging the flooded core sample by:
directing a magnetic field through the passage in a direction along the longitudinal axis of the passage;
selectively directing a gradient field through the passage;
selectively pulsing a radio frequency field through the passage in a direction orthogonal to the longitudinal axis of the passage; and
generating images of the fluid in the core sample during the pulsing whereby images of hydrocarbons and aqueous fluids in the core sample are generated based on differences in chemical shift, wherein nuclear magnetic resonance measurement is performed using compressed sensing and rapid acquisition with relaxation enhancement (RARE).

### Claim 8 (depends on 7)

The method of claim 7, further comprising rotating the core sample and repeating the selectively pulsing.

### Claim 9 (depends on 7)

The method of claim 7, further comprising validating the generated images by generating reference images of the core sample using contrast imaging and comparing the reference images with the generated images.

### Claim 10

A method of imaging fluid positioned in a subsurface formation, the method comprising:
positioning a core sample of the subsurface formation in a fluid filled passage of an imager;
directing a magnetic field through the passage in a direction along a longitudinal axis of the passage;
selectively directing a gradient field through the passage;
directing a radio frequency field through the passage in the direction orthogonal to the longitudinal axis of the passage;
selectively acquiring nuclear magnetic resonance measurements of the fluid in the core sample by selectively pulsing frequencies of the radio frequency field to the core sample and applying the gradient field to the core sample according to a pre-determined k-space sampling plot; and
generating images of the fluid in the core sample during the pulsing whereby images of hydrocarbons and aqueous fluids in the core sample are generated based on differences in chemical shift, wherein the selectively acquiring nuclear magnetic resonance measurement is performed using compressed sensing and rapid acquisition with relaxation enhancement (RARE).

### Claim 11 (depends on 10)

The method of claim 10, wherein positioning comprises positioning the imager in a downhole tool and deploying the downhole tool in the wellbore.

### Claim 12 (depends on 11)

The method of claim 11, further comprising after positioning the core sample in the passage of the imager, passing fluid from the formation into the passage to fill the passage.