Methods for predicting dynamic sag using viscometer/rheometer data

Patent metadata

Field	Value
Publication number	US-9513203-B2
Application number	US-201213492885-A
Country	US
Kind code	B2
Filing date	Jun 10, 2012
Priority date	Jun 10, 2012
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A method for quantitatively determining dynamic barite sag in drilling fluids includes measuring rheological properties with viscometers and/or rheometers, and introducing the parameters into an equation to obtain the sag rate.

First claim

What is claimed is:

1. A method comprising:
measuring rheological data for a plurality of fluids having particulates suspended therein, wherein the rheological data is selected from the group consisting of: a shear stress, a yield stress, a viscosity, a shear-thinning index, and any combination thereof;
applying a pseudo-plastic model and a visco-plastic model to the rheological data to produce characteristic parameters for each of the plurality of fluids;
applying the characteristic parameters for each of the plurality of fluids to an equation to predict a dynamic sag rate for each of the plurality of fluids, wherein the equation is: (4/3)*π*a i 3 *(ρ s −ρ f )*g=6*π*a i *U i *(μ+k*(T 0 HB ) 1/n ). wherein a i , is a radius of the particulates, ρ s is a density of the particulates, ρ f is a density of the fluid surrounding the particulates, g is acceleration due to gravity, U i is the dynamic sag rate of particulates of size a i , μ is a viscosity of the fluid, γ is a shear rate, k is an empirical constant that ranges from 0.01 to 10, T 0 HB is a yield stress, and n is a shear thinning index; and
formulating a drilling fluid based on the dynamic sag rate for each of the plurality of fluids so as to minimize sag in the drilling fluid.

2. The method of claim 1 further comprising: drilling a wellbore with the drilling fluid.

3. The method of claim 1 , wherein measuring rheological data is performed at a shear rate of 5 s −1 .

4. The method of claim 1 , wherein the pseudo-plastic model is selected from the group consisting of a power-law model, an Eyring model, a Cross model, a Carreau model, an Ellis model, and any combination thereof.

5. The method of claim 1 , wherein the visco-plastic model is selected from the group consisting of a Bingham-plastic model, a Casson model, a Herschel-Bulkley model, and any combination thereof.

6. A method comprising:
measuring rheological data for a plurality of fluids having particulates suspended therein, wherein the rheological data is selected from the group consisting of: a shear stress, a yield stress, a viscosity, a shear-thinning index, and any combination thereof;
applying a pseudo-plastic model and a visco-plastic model to the rheological data to produce characteristic parameters for each of the plurality of fluids;
applying the characteristic parameters for each of the plurality of fluids to an equation to predict a dynamic sag rate for each of the plurality of fluids, wherein the equation is: (4/3)*π*a i 3 *(ρ s −ρ f )*g=6*π*a i *U i *(μ+k*(T 0 HB ) 1/n ) wherein a i , is a radius of the particulates, ρ s is a density of the particulates, ρ f is a density of the fluid surrounding the particulates, g is acceleration due to gravity, U i is the dynamic sag rate of particulates of size a i , μ is a viscosity of the fluid, γ is a shear rate, k is an empirical constant that ranges from 0.01 to 10, T 0 HB is a yield stress, and n is a shear thinning index; and
adjusting a drilling fluid composition based on the dynamic sag rate for each of the plurality of fluids so as to minimize sag in the drilling fluid.

Assignees

• Kulkarni Sandeep
• Savari Sharath
• Teke Kushabhau D
• Jamison Dale E
• Murphy Robert J
• Gantepla Anita
• Halliburton Energy Services Inc

Inventors

• Kulkarni Sandeep
• Savari Sharath
• Teke Kushabhau D
• Jamison Dale E
• Murphy Robert J
• Gantepla Anita

Classifications

• G01N11/00

  Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties · CPC title

• G01N15/04 Primary

  Investigating sedimentation of particle suspensions · CPC title