- Contaminants Because of the rotation of the drilling fluids in the wellbore and the affluence of force fluids into it there are numerous mud pollutants that includes in it. These pollutants prompt the computations of Yield Point( PV) making these an important factor to consider when dealing with the value of Yield Point( PV). These pollutants might include carbon dioxide( CO2), swab and anhydriteetc.

-Over Treatment numerous chemicals and fusions are added in water- grounded guck for different reasons. Their volume mixed in the mud if not managed duly might affect the values of Yield Point( PV). These chemicals include lime or acidulous soda pop.

Following factors are affecting Yield Point( YP) in oil painting- grounded guck making its value increase
Drill slices Value of Yield Point( YP) increases with the increase in drilled slices from the conformation. slices that are circulated back to the face when present in the oil painting- grounded mud effect the value of Yield Point( YP).

response of Lime( CaO) in the mud with the CO2 Lime( CaO) is frequently added in the oil painting- grounded mudwhich when chemically reacts with the CO2 in the mud forms Calcium Carbonate( CaCO3) that contribute towards the proliferation in the value of Yield Point( YP).

Lower Temperature On contrary to the water- grounded mud, it's the lower temperature that's affecting Yield Point( YP). Lower the temperature in oil painting- grounded mudadvanced will be the density and further will be the value of Yield Point( YP).

Yield Point in Drilling Mud Applications

The Yield Point( YP) of the drilling mud has a veritably introductory and important function in the drilling. Some of its operations in the drilling field of the petroleum assiduity are stated as follows

Carrier of Drilled slices When the drilling bit at the end of the drill string cut through the conformation it's veritably important to remove those slices from the face of the bit and avoid the accumulation of drilled slices in the borehole. else, the effectiveness of the drilling is seriously hovered . Yield Point( YP) value demonstrates the capability of the drilling mud to carry back those drill bit slices to the face.

fellow Circulating viscosity( ECD) fellow Circulating viscosity( ECD) generally increases with the increase in Yield Point( YP) value.

Borehole cleaned As explained before that's important to keep the drag hole clean for better penetration rate. So, the advanced the periphery of borehole, more should be the Yield Point( YP) value of the drilling mudto support a better cleaning of the borehole.

Yield Point & Drilling Mud Complements

numbers la and b indicate the relationship between PV and specific weight and between YP and specific weight of drilling fluids with solids. The curve points on these angles reflect the changes in the physicochemical conditions of drilling fluids. From these graphs, one can see that both PV and YP are related to the same important property of drilling fluid( i.e., viscosity). Accordingly, YP values can be colluded as a function of PV.

FIGUREI. Interrelationship among plastic density, yield point, and viscosity.( a) PV- versus- YP angles for fresh- water slush;( b) stabilized( with chemicals) brackish mud; and( c) flocculated, clotted fresh- water mud.

Figure I shows such a relationship between YP and PV for an undressed brackish drilling fluid( wind I), for a stabilized drilling fluid system( wind II), and for a clotted mud system( wind Ill). The mud- condition angle α decreases with adding degree of stabilization and increases with adding degree of coagulation and flocculation.

In the undressed drilling fluid systems( Figure I, wind 1), point M1 moves overhead along the wind with adding complexion content. Stabilizers reduce YP, as point M1 shifts to N1. The effectiveness of treating agents depends on the stabilization length( M1N1) 

and on the stabilization angle β. The degree of stabilization depends on both the type and effectiveness of the stabilizer and on the complexion content in the system. The stabilization length depends on the number of chemicals introduced.

Advanced- molecular- weight agents appear to affect in lesser stabilization angle. All other variables remaining the same, the stabilization angle increases in the presence of advanced complexion content. Point M1 moves along the MINI line with the addition of low- molecular- weight complements, similar as soda pop ash.

Clotted drilling fluid systems are characterized by lower values of stabilization distance OK and by lesser mud- condition angle α, which means a advanced YP/ PV rate. With the addition of jelling agent, point M1 moves to point N1. In this case, the degree of coagulation is measured by coagulation angle γ and coagulation length( M1N1).

In addition of water or stabilizer, the shift of point M3 on wind III( Figure Ic) is analogous to the shift of point MI under the same conditions.On addition of complexion, wind III shifts toward undressed mud( wind IlIa) and point M3 moves to M ’ 3, because adding complexion content causes reduction of the coagulant attention per unit volume of complexion( solid phase).

Stabilized drilling fluid systems are characterized by a lower mud- condition angle α, which means a lower YP/ PV rate, and by larger values of stabilization distance OK. The goods of water, stabilizer, or coagulant on a point on wind II are analogous to those on the point MI on wind I under the same conditions. wind II shifts toward undressed mudby the addition of complexion( wind lIa), as point M2 moves to M ’ 2 because the addition of complexion results in lowering the attention of stabilizing agent per unit volume of complexion.
The pens conducted expansive trials on assessing the mileage of PV- versus- YP angles. Both freshwater and saltwater guck were tested using colorful proportions of tones, weighting accoutrements , dispersants, and coagulants. Responses of PV- versus- YP angles to colorful complements were also estimated.

Effect of  Barite on Bentonite Mud

of the angles represents constant attention of barite- 2, 5, 8, 12, and 20. The attention of bentonite complexion were the same as those of the reference wind. The addition of barite doesn't appear to change appreciably the mud- condition angle α. The angles shift to the right with adding attention of barite due to the increase of plastic density with adding solids content.

Effect of Thinners on Bentonite Mud

Four different types of thinners have been tested by the pens
-SAPP( sodium acid pyrophosphate)
-Ferrochrome lignosulfonate( Q- Broxin)
-Lignosulfonate
-Lignite






The performing PV- versus- YP angles are resemblant( same YP/ PV pitch). Both PV and YP increased with adding attention of Ca( OHlz. The YP increased appreciably





The pitches of three lines were equal, with only a slight drop in Pv. Coagulation angle γ is larger for Ca( OH) z than for NaCl, because Ca( OH) 2 has lesser flocculation power than NaCI.

Effect of Impermex and Carboxymethylcellulose on Salt- Saturated Mud

Both PV and YP increase with adding attention of bounce; the YP/ PV pitch remains constant. Because of better stabilization, the mud- condition angle α decreases on adding bounce to saltwater Zeogel mud.

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