# US 12,007,368 B2 · Fragile and normal viscoelastic components of drilling fluid gels

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- Number: US 12,007,368 B2
- Document ID: US12007368B2
- Status: Granted
- Kind: B2
- Application number: 16/971,274
- Filed: 2019-09-24
- Published: 2023-03-30
- Granted: 2024-06-11
- Earliest claimed: 2019-09-24
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Dale E. Jamison; Sandeep Kulkarni; Xiangnan Ye
- Web page: https://patentgrep.com/patent/US12007368B2

## CPC

- E21B 29/10: Reconditioning of well casings, e.g. straightening
- G01N 3/56: Investigating resistance to wear or abrasion
- 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 43/2607: {Surface equipment specially adapted for fracturing operations}
- G01N 3/34: generated by mechanical means, e.g. hammer blows
- G01N 11/14: by using rotary bodies, e.g. vane (G01N11/16 takes precedence)
- G01N 2203/0025: Shearing
- G01N 2203/0094: Visco-elasticity
- 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)

## Abstract

Characterizing the decay of the microstructure of a drilling fluid gel using a model based on two exponential functions. Based on the model, identify at least two components of the decay model comprising a fast decay component and a slow decay component, wherein the fast decay component decays more quickly than the slow decay component. The decay of the microstructure of the gel over a time period can be determined using a rheometer or viscometer. Wellbore processes, including start up and tripping operations can be optimized based on the determination of the fast decay component and/or a slow decay component of the drilling fluid gel.

## Claims

### Claim 1

A method, comprising:
receiving a measured decay of a microstructure of a gelled fluid over a time period in response to a shear stress imposed on the gelled fluid exceeding a peak gel strength of the gelled fluid;
modeling the decay of the microstructure during the time period to form a decay model;
identifying at least two components of the decay model comprising a fast decay component and a slow decay component, wherein the fast decay component decays more quickly than the slow decay component;
initiating operation of a drill; and
activating a drilling pump based on timing of the fast decay component and the slow decay component relative to an acoustic velocity of the gelled fluid.

### Claim 2 (depends on 1)

The method of claim 1, comprising:
drilling a wellbore using the gelled fluid and carrying out an additional wellbore process based on the decay model.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
applying the shear stress to the gelled fluid, the gelled fluid having the microstructure, the shear stress being applied until the peak gel strength of the gelled fluid is exceeded.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
measuring the decay of the microstructure of the gelled fluid over the time period after the peak gel strength of the gelled fluid is exceeded.

### Claim 5 (depends on 1)

The method of claim 1, wherein the shear stress is applied via a blade coupled with a motor.

### Claim 6 (depends on 1)

The method of claim 1, wherein the shear stress is measured with a viscometer or rheometer.

### Claim 7 (depends on 1)

The method of claim 1, wherein the time period extends from the peak gel strength of the gelled fluid to a complete degradation of the microstructure.

### Claim 8 (depends on 7)

The method of claim 7, wherein the complete degradation of the microstructure corresponds to a shear stress at a preselected steady state shear rate of a viscometer.

### Claim 9 (depends on 1)

The method of claim 1, wherein the microstructure of the gelled fluid degrades after the peak gel strength is exceeded thereby decreasing viscosity of the gelled fluid.

### Claim 10 (depends on 1)

The method of claim 1, wherein the decay model includes an exponential decay function.

### Claim 11 (depends on 1)

The method of claim 1, wherein the decay model includes two exponential decay functions.

### Claim 12 (depends on 1)

The method of claim 1, wherein the decay model is based on the following formula:
σ(t)=(σgel−A1)e−B0t+A1eB1t+σss
wherein
σ is shear stress;
σss is steady state shear stress;
t is time
A1 is a constant equivalent to a magnitude of the gel stress;
B0 and B1 are decay time constants solved numerically based on the received measured decay of the microstructure of the gel over a time period.

### Claim 13 (depends on 12)

The method of claim 12, wherein at least one of a first exponential function (σgel−A1)e−B0t or a second exponential function A1eB1t corresponds to the fast decay component and the other the slow decay component.

### Claim 14

A system comprising:
one or more processors; and
a non-transitory memory coupled to the one or more processors, wherein the memory comprises instruction configured to cause the one or more processors to perform operations for:
receiving a measured decay of a microstructure of a gelled fluid over a time period in response to a shear stress imposed on the gelled fluid exceeding peak gel strength of the gelled fluid;
modeling the decay of the microstructure during the time period to form a decay model;
identifying at least two components of the decay model comprising a fast decay component and a slow decay component, wherein the fast decay component decays more quickly than the slow decay component and a wellbore is drilled when the gelled fluid is in the wellbore; and
activating a drilling pump based on timing of the fast decay component and the slow decay component relative to an acoustic velocity of the gelled fluid.

### Claim 15 (depends on 14)

The system of claim 14, wherein the decay model is based on the following formula:
σ(t)=(σgel−A1)e−B0t+A1eB1t+σss
wherein
σ is shear stress;
σss is steady state shear stress;
t is time
A1 is a constant equivalent to a magnitude of the gel stress;
B0 and B1 are decay time constants solved numerically based on the received measured decay of the microstructure of the gel over a time period.

### Claim 16 (depends on 15)

The system of claim 15, wherein at least one of a first exponential function (σgel−A1)e−B0t or a second exponential function A1eB1t corresponds to the fast decay component and the other the slow decay component.

### Claim 17 (depends on 14)

The system of claim 14 wherein the measured decay of the microstructure of the gel over the period of time is obtained based on applying the shear stress to the gelled fluid, the gelled fluid having the microstructure, the shear stress being applied until the peak gel strength of the gelled fluid is exceeded.

### Claim 18 (depends on 17)

The system of claim 17, wherein the shear stress was applied via a blade coupled with a motor.