Cutting Carrying Index – Simple Tool To Determine Hole Cleaning

To get the good idea on how good of the hole cleaning is, the another method called Cutting Carrying Index (CCI) is utilized. The CCI is an empirical relationship from real data and the equation is below:

CCI = (K × AV × MW )÷(400,000) — Equation 1

Where;

AV is annular velocity in ft/min.

MW is mud weight in ppg.

K is a Power Law Constant.

The Power Law constant (K) can be calculated from the equation below:

Where;

PV is plastic viscosity in centipoises.

YP is yield point in lb/100sqft

n is flow behavior index.

The flow behavior index (n) can be determined by the following equation:

Where;

PV is plastic viscosity in centipoises.

YP is yield point in lb/100sqft

How will the CCI tell you about hole cleaning?

If CCI is equal to 0.5 or less, the hole cleaning is poor and the hole problem may be seen.

If CCI is equal to 1.0 or greater, it indicates that the hole cleaning is good.

Please follow the example to determine CCI.

Mud Weight = 9.2 ppg

Annular Velocity = 140 ft/min

Plastic viscosity = 17 cp

Yield Point = 15 lbs/100 sq ft

Determine “n”

n= 0.61472

Determine “K”

K = 353.71

CCI=(353.71(140)(9.2))/400,000

CCI = 1.14

From the given drilling parameters, the hole cleaning is excellent.

Reference books:

American Society of Mechanical Engineers. (2005). Drilling Fluids Processing Handbook. 1st ed. Gulf Professional Publishing.

Caenn, R., Darley, H. and Gray, G. (n.d.). Composition and properties of drilling and completion fluids. 7th ed. Houston: Gulf Professional Publishing.

Philips, A. (n.d.). So you want to be a mud engineer. 1st ed. Houston: CreateSpace Independent Publishing Platform.

Van Dyke, K. (2000). Drilling fluids. 1st ed. Austin, Tex.: Petroleum Extension Service, Continuing & Extended Education, the University of Texas at Austin, in cooperation with International Association of Drilling Contractors, Houston, Tex.