Mud Density

Topics: Viscosity, Non-Newtonian fluid, Continuum mechanics Pages: 15 (3677 words) Published: January 14, 2013
Pet E 367
Lab Report #1
* Yield of Bentonite and Attapulgite Clays
* Rheological Characterization of Water-Base Drilling Fluids Experiment Date: January 31 2007

Prepared by: Jackie Chee (1103396)
Group #7
Beattie L.
Branch T.
NREF 2-052
Markin/CNRL Natural Resources Engineering Facility
116street 91st ave

February 13, 2007
Barkim Demirdal
PhD Candidate at Petroleum Engineering Department
7-134 Markim CNRL Natural Resources Engineering Facility
Edmonton, Alberta
Canada T6G 2W2

Dear Mr. Demirdal,
Drilling mud is important in the petroleum industry. Drilling mud can be composed of various types of clay. All the clays have their unique properties and when prepared with water, they will exhibit different viscosity, gel strength, and most importantly, the rheological characteristic of the drilling mud. We are required to observe the difference between Bentonite, and Attapulgite clay in both salt water and fresh water. It was also required to differentiate the few non-Newtonian fluid models, and determine the model associated with Bentonite, and Xanthan Gum.

It is clear that Bentonite and Attapulgite give different characteristic to the drilling mud. Bentonite has a low yield of clay and it is highly ineffective in salt water. Attapulgite have a high yield of clay and it does not shown any significant signs of swelling. Bentonite encountered severe swelling when mixed with fresh water. Overall, Attapulgite would be a better choice when making drilling mud.

Bentonite with fresh water exhibits Bingham Plastic properties while the Xanthan Gum with fresh water showed a fluid with a Power Law model.

I hope these observations will be of good use to you.
Thank you for your time


(Jackie Chee)

* Objective
This lab is primarily divided into 2 parts. Part 1 of this lab is to determine how bentonite and attapulgite clay affects viscosity in both water and salt water. Part 2 is to determine the rheological model describing the relation between shear stress and shear rate in a water based drilling fluid. * Theory and concept

Properties of water based drilling mud are controlled mainly by the type of clay added to the drilling fluid to change its properties for better wellbore efficiency. The first part of the lab will produce twelve samples. There will be bentonite or attapulgite added to either salt water or water. The amount of clay added will be 3, 6 and 9% of the weight of water. The density and viscosity will be determined. Density will be determined using the mud balance; and viscosity will be determined using the Fann VG meter (rotational viscometer). There will also be a marsh funnel used to determine relative viscosity to water. Water will only be used for this part of the experiment. Mud Density

Density is the weight per given volume. Measuring the density of the drilling fluid is important to determine the buoyancy force induced when drilling and the hydrostatic pressure the drilling fluid acts at the bottom-hole pressure. A higher density will prevent formation fluid from entering the well bore. In this lab, the density is determined using the mud balance shown in Figure 1. The mud cup takes a fixed volume of fluid sample and by adjusting the rider until balanced, a reading can be taken. This apparatus has to be calibrated using fresh water.

Figure 1
Mud Balance

Thixotropy or the Gel strength is measured at a low shear stress after allowing it to thicken/sit for a given amount of time (10 seconds and 10 minutes by API standards). The strength of the mud cake formed will help in preventing water from entering the wellbore, as well as the drilling fluid circulating in the wellbore to leak out into a fracture. Viscosity

Part 1
Viscosity is the fluid’s resistance to flow. The viscosity of the mud determines the efficiency and even ability to...
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