Mud Density Sample Essay

Boring clay is of import in the crude oil industry. Boring clay can be composed of assorted types of clay. All the clays have their alone belongingss and when prepared with H2O. they will exhibit different viscousness. gel strength. and most significantly. the rheological feature of the boring clay. We are required to detect the difference between Bentonite. and Attapulgite clay in both salt H2O and fresh H2O. It was besides required to distinguish the few non-Newtonian fluid theoretical accounts. and find the theoretical account associated with Bentonite. and Xanthan Gum.

It is clear that Bentonite and Attapulgite give different feature to the boring clay. Bentonite has a low output of clay and it is extremely uneffective in salt H2O. Attapulgite have a high output of clay and it does non shown any important marks of swelling. Bentonite encountered terrible swelling when assorted with fresh H2O. Overall. Attapulgite would be a better pick when doing boring clay.

Bentonite with fresh H2O exhibits Bingham Plastic belongingss while the Xanthan Gum with fresh H2O showed a fluid with a Power Law theoretical account.

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* Objective
This lab is chiefly divided into 2 parts. Part 1 of this lab is to find how bentonite and attapulgite clay affects viscousness in both H2O and salt H2O. Part 2 is to find the rheological theoretical account depicting the relation between shear emphasis and shear rate in a H2O based boring fluid. * Theory and construct

Properties of H2O based boring clay are controlled chiefly by the type of clay added to the boring fluid to alter its belongingss for better wellbore efficiency. The first portion of the lab will bring forth 12 samples. There will be bentonite or attapulgite added to either salt H2O or H2O. The sum of clay added will be 3. 6 and 9 % of the weight of H2O. The denseness and viscousness will be determined. Density will be determined utilizing the clay balance ; and viscousness will be determined utilizing the Fann VG metre ( rotational viscosimeter ) . There will besides be a marsh funnel used to find comparative viscousness to H2O. Water will merely be used for this portion of the experiment. Mud Density

Density is the weight per given volume. Measuring the denseness of the boring fluid is of import to find the perkiness force induced when boring and the hydrostatic force per unit area the boring fluid Acts of the Apostless at the bottom-hole force per unit area. A higher denseness will forestall formation fluid from come ining the well bore. In this lab. the denseness is determined utilizing the clay balance shown in Figure 1. The mud cup takes a fixed volume of unstable sample and by seting the rider until balanced. a reading can be taken. This setup has to be calibrated utilizing fresh H2O.

Figure 1
Mud Balance
Beginning: hypertext transfer protocol: //www2. Mountain Time. dk/udgiv/Publikationer/2001/87-7944-820-8/html/kap01. htm

Thixotropy
Thixotropy or the Gel strength is measured at a low shear emphasis after leting it to thicken/sit for a given sum of clip ( 10 seconds and 10 proceedingss by API criterions ) . The strength of the claies cake formed will assist in forestalling H2O from come ining the wellbore. every bit good as the boring fluid circulating in the wellbore to leak out into a break. Viscosity

Part 1
Viscosity is the fluid’s opposition to flux. The viscousness of the clay determines the efficiency and even ability to raise film editings out of the well bore. Addition of different types of clay will impact the viscousness every bit good as the usage of salt H2O as oppose to kick H2O. Using an API criterion Fann VG metre. the evident viscousness is defined as:

?App= [ 600 rpm dial reading ] 2

Figure 2
Conventional diagram of a homocentric cylindrical viscosimeter
Part 2
The Fann VG metre besides has assorted rotary motion velocities. all of which is utile to find the boring unstable rheological theoretical account for shear emphasis to shear rate. The chief constituents will be two cylinders ; one will be referred as the Rotor. and the other the Bob. The Rotor is the external cylinder that is connected to the motor giving it a changeless angular speed. The interior cylinder. the Bob is connected to a spring that gives a dial read out. Both cylinders are submerged into the fluid and there is a little annulate infinite in between the Rotor and Bob ; when the Rotor is revolving. the fluid will do a torsion on the Bob. Depending on the dimensions. the Fann VG metre used had this relation to shear emphasis:


?= ?
Where: ? = shear emphasis [ lbf/100 ft2 ]
? =Dial reading
The shear rate is determined by:
?=1. 7*rpm
Where: ?= shear rate [ sec-1 ]
revolutions per minute = revolutions per minute





Figure 3
Newtonian Model
Most Drilling fluids are non-Newtonian fluids. either viscousness alterations with shear rate ( Internet Explorer. Power Law Model or Herschel-Bulkley Model ) . or a fictile output must be overcome ( Internet Explorer. Bingham Plastic Model ) . A Newtonian theoretical account is the simplest. The shear emphasis is straight relative to the shear rate as shown in figure 2. Common twenty-four hours liquids are Newtonian like H2O. honey and oil. The changeless proportionality associating the two is called viscousness.

Figure 4
Bingham Plastic Model

A Bingham Plastic Model is similar to a Newtonian theoretical account ; nevertheless it requires a fictile output to be overcome before any shearing in the fluid will happen. The relation between shear emphasis and shear rate is shown in figure 3 and can be expressed as:

?=?y+?p*?
?p=?600-?300
?y=?300-?p

Where: ? = Shear emphasis [ lbf/100 ft2 ]
?y = output point [ lbf/100 ft2 ]
?p = Plastic Viscosity [ cp ]
? = Shear Rate [ sec-1 ]
?600 = dial reading at 600rpm
?300 = dial reading at 300rpm




Figure 5
Power Law Model

A Power Law Model is similar to a Newtonian theoretical account. nevertheless it has no one-dimensionality as shown in figure 4. The shear rate and shear emphasis are related through an exponential term. ‘n’ which is the flow behaviour index. A power jurisprudence theoretical account can be expressed as:

?=K* ( ? ) N
n=3. 322*log? ( ?600?300 )
K=510*?300 ( 511 ) N
Where: ? = Shear emphasis [ lbf/100 ft2 ]
K= Consistency index [ lbf/100 ft2 ]
? = Shear Rate [ sec-1 ]
n = flow behaviour index
?x = dial reading at x revolutions per minute
Flow behaviour index ‘n’| Type of fluid|
& lt ; 1| Pseudoplastic. or shear cutting ; an addition in shear rate consequences in a lessening in viscosity| 1| Newtonian ; shear rate and shear emphasis are straight proportional| & gt ; 1| Dilatants. or shear thickener ; an addition in shear rate consequences in an addition in viscosity|








Figure 6
Herschel-Bulkley Model

A Herschel-Bulkley Model is fundamentally a Power Law theoretical account with a Bingham plastic theoretical account combined together. A fictile output is required to originate flow. and one time the fluid is syrupy. the relation between shear emphasis and shear rate is similar to one of the Power Law Model. This can be shown in figure 5. This can be express as:

?=?y+K* ( ? ) N
Where: ? = Shear emphasis [ lbf/100 ft2 ]
K= Consistency index [ lbf/100 ft2 ]
? = Shear Rate [ sec-1 ]
n = flow behaviour index
?y = Yield Stress [ lbf/100 ft2 ]
With four different theoretical accounts in head. the choice of the appropriate theoretical account is done by plotting shear emphasis as a map of shear rate will give one of the 4 curves. Linear arrested development is used to find the line of best tantrum. The two lowest revolutions per minute reading. normally 3rpm and 6rpm can be neglected from the plotting. The low revolutions per minute give an inaccurate reading because the fluid is about at a base still and gel strengthening is happening. * Experimental Procedure





Part 1
1. Calibrate clay balance utilizing fresh H2O. ( Fresh Water Density at 21 ?C ) : 8. 3 lb/gal 2. Measure the funnel viscousness of H2O at room temperature. ( Water: 26 seconds ) 3. Twelve samples will be prepared in this lab subdivision. Six of these will be assorted utilizing fresh H2O. and the other six with salt H2O. One-half of those six samples. three samples. will be assorted utilizing 3 % . 6 % or 9 % of Bentonite or Attapulgite by weight of H2O. Fresh Water| Salt Water ( 20. 000 ppm NaCl ) |

Bentonite| Attapulgite| Bentonite| Attapulgite|
Each sample will be assorted with 3 % . 6 % or 9 % of clay by weight of H2O. 4. Obtain 350cc of either fresh or salt H2O in the commixture cup and get down liquidizer. 5. Obtain right sum of clay from bulk container.

6. Using a spatula. easy and carefully. add sensible sums of clay into the mixing cup while liquidizer is on. Be careful with spatula hitting the sociable and clay dust whiffing into the air. Avoid inhaling clay dust. 7. Mix sample for a lower limit of 10 proceedingss or when sample is good assorted. 8. Topographic point sample into Fann VG viscosimeter and step evident viscousness of sample at 600 revolutions per minute. Apparent viscousness can be calculated utilizing expression from theory. 9. Measure denseness of sample utilizing mud balance.

10. Dispose of sample decently. clean equipment and repetition with the other samples until done. Separate 2
1. Calibrate clay balance utilizing fresh H2O. ( Fresh Water Density at 21 ?C ) : 8. 3 lb/gal 2. Measure the funnel viscousness of H2O at room temperature. ( Water: 26 seconds ) 3. Two samples will be prepared in this lab subdivision. Both will utilize fresh H2O. One sample will hold 35 gms of bentonite. and the either will hold 4 gms of Xanthan Gum. 4. Obtain 350cc of either fresh or salt H2O in the commixture cup and get down liquidizer. 5. Obtain right sum of clay from bulk container.

6. Using a spatula. easy and carefully. add sensible sums of clay into the mixing cup while liquidizer is on. Be careful with spatula hitting the sociable and clay dust whiffing into the air. Avoid inhaling clay dust. 7. Mix sample for a lower limit of 10 proceedingss or when sample is good assorted. 8. Record clay temperature utilizing digital thermometer. Topographic point thermometer good in the centre of the clay. avoiding contact with the blending cup. 9. Measure denseness of sample utilizing mud balance.

10. Topographic point sample into Fann VG viscosimeter and record dial readings at 600. 300. 200. 100. 6 and 3 revolutions per minute.
11. Determine 10 sec and 10 minute gel strength.
12. Dispose of sample decently. clean equipment and repetition with the other samples until done.

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