Mud Calculations
-
Upload
fatima-khalid -
Category
Documents
-
view
275 -
download
0
Transcript of Mud Calculations
-
8/11/2019 Mud Calculations
1/17
Writing expressions for these assumptions :
Volume basis :Vs + Vi =Vf . . . . . . . . . . . . . . . . . (1)
Weight basis : sVs + iVi = fVf . . . . . . .. . . . (2)Where
Vs = Volume of solidVi = Volume of initial mud (or any liquid)
Vf = Final volume of mixture
s = Density of solid
i = Density of initial mud
f = Density of final mudSolving for Vs :
Vs = Vf (f i) . . . . . . . . . . . . . . . (3)(s i)
-
8/11/2019 Mud Calculations
2/17
The units have to be in consistent set
If the density is in lb/gal, the V will be in gal, and sodoes gm/cc cc.
Since the net volume of a powdered solid is not readilymeasurable (usually measured by weight), bymultiplying the s to equation (3), the Vs can becalculated :
sVs =sVf (fi) . . . . . . . . . . . . (4)(s i)
-
8/11/2019 Mud Calculations
3/17
Example 1A 9.5 lb/gal mud contains clay (SG = 2.5) and fresh water.Compute (a) the volume % and (b) the weight % clay in thismud.
Using Equations (3) & (4)
Solution :
(a) Altering eq. (3)
Volume % solids = Vs 100%
Vf
= f i 100% = 9.4 %s - i
-
8/11/2019 Mud Calculations
4/17
(b) Divide eq. (4) fVf :
Weight % solids = sVs 100
fVfSubstitute Vs & Vf in terms od densities := 20.6%
-
8/11/2019 Mud Calculations
5/17
Example 2 For laboratory purposes, it is desired to mix one liter of
bentonite- fresh water mud having a viscosity of 30 cP:
(a) What will be the resulting mud density ?
(b) How much of each material should be used ?
Hints for Solution :
Assume Wyoming bentonite,
Solid content = 3 % by volume
-
8/11/2019 Mud Calculations
6/17
For certain types of problems it is convenient to express eq.(3) in a different form.
Suppose that the quantity of solids (Vs) necessary toincrease (or decrease) the density of an initial mud isdesired. Then :
Vs = (Vi + Vs) (f i) . . . . . . . . . . (3a)
s iWhere ; Vi + Vs = Vf . . . . . . . . . . . (from eq. 1)
Solving for Vs gives :Vs = Vi (f i) . . . . . . . . . . . . . . . (5)
(s f)
-
8/11/2019 Mud Calculations
7/17
Example 3(a) How much weighting material BaSO4, barite, SG =
4.3) should be added to the mud of Example 2 toincrease its density to 10 ppg ?
(b) What will be the resulting volume ?Hint for Solution :
Use eq. (5)
-
8/11/2019 Mud Calculations
8/17
Barite is so universally used as a weighting material, it isuseful to express eq. (5) in field units.
Barite is sold in 100 lb bags or sacks :
1 sack = 100 lb = 0.373 cu.ft
4.3 (62.4 lb/cu.ft)
= 0.373 cu.ft = 0.0664 bbl of net5.615 cu.ft/bbl barite
Therefore, 1 bbl (net) of barite = 1 bbl = 15 sacks0.0664 bbl/sack
Note : Assuming SG of Barite = 4.3
-
8/11/2019 Mud Calculations
9/17
Let Sb = Sacks of barite necessary to increase the density ofVi bbl of mud from i to f.
Substituting these special conditions into eq. (5):
Sb = Vi (f i)15 4.3 (8.33) f
Therefore;
Sb = 15 Vi (f i) . . . . . . . . . . . . (5a)35.8 - f
-
8/11/2019 Mud Calculations
10/17
Similarly, if clay (SG = 2.5) is sold in 100 lb bags orsacks :1 sack = 100 lb = 0.641 cu.ft
2.5 (62.4 lb/ cu.ft)= 0.641 cu.ft = 0.1142 bbl of net clay
5.615 cu.ft/ bbl
1 bbl (net) of clay = 1 bbl = 8.75 sacks
0.1142 bbl/sack
Let Sc = Sacks of clay necessary to increase the density ofVi bbl of mud from i to f.
-
8/11/2019 Mud Calculations
11/17
Substituting these special conditions into eq. (5):
Sc = Vi (f i)
8.75 2.5(8.33) f
Therefore, Sc = 8.75 Vi (f i) . . . . . . . . . . . . (5b)
20.8 - f
-
8/11/2019 Mud Calculations
12/17
Example 4(a) How many sacks of barite are necessary to increase
the density of 1000 bbl of mud from 10 to 14 lb/ gal ?
(b) What will be the final mud volume ?
Hint for solution :
Use eq. (5a)
-
8/11/2019 Mud Calculations
13/17
To dilute or reduce mud density :
Vw + Vi = Vf . . . . . . . . Volume basis
wVw + iVi = fVf . . . . . . . . Weight basis
wVw + iVi = f(Vw + Vi)
wVw fVw = fVi iVi
Vw = Vi (f i)
wf
Vw = Vi (i f) . . . . . . . . . . . . . . . . . (6)
(f w)
-
8/11/2019 Mud Calculations
14/17
where,
Vw = bbls of water necessary to reduce the density of Vibbls initial mud from i to f.
-
8/11/2019 Mud Calculations
15/17
Example 5(a) How much fresh water must be added to 1000 bbl of12 lb/gal mud to reduce its density to 10 lb/gal ?
(b) What will be the resulting volume ?
Hints for solution :
(a) Use eq. (6)
-
8/11/2019 Mud Calculations
16/17
Example 6(a) How many sacks of barite are required to raise the
mud weight of 755 bbl from 77 pcf to 92 pcf ? Whatis the resulting volume ?
(b) Calculate the new mud weight when 126 bbl of oil(SG= 0.8)is added to the new system. What is theresulting volume ?
(c) Determine the quantity of barite required tomaintain a mud weight of 92 pcf. What is the finalvolume ?
-
8/11/2019 Mud Calculations
17/17
Hints for solution :
Use eq. (5a)