Designing a barite draw to physically block the wellbore is kindly
more complicated. The generally accepted system is to mix a slurry so that the barite settles out from the slurry into a hard draw which will block the wellbore. The rate that barite will settle into a hard draw is generally slow and predictable. Fairly accurate field prognostications may be made from an observation of the original barite settling rate in a small vessel. The original rate is constant and independent of the height of the slurry. The original settling rate lasts for a short period of time, after which the settling rate diminishments as smaller barite patches remain in suspense. In a vessel one bottom high, the original settling rate applies for roughly five twinkles. In a field situation with 500 or further bases( 150 or further measures) of barite slurry, the original rate may apply for a day or longer. The quantum of barite settling in a shorter period can be reckoned as the product of the original rate times the waiting time.

Field experience has shown that slurries of over to 20 lbs/ girl(2.40 SG) are fairly fluently prepared using only Base Oil, EZ MUL( Oil Wetting Agent), DRILTREAT, and Barite for oil painting guck . Water, SAPP, acidulous soda pop, and barite are used for Water base mud.

Barite Plug Preparation

From a practical point of view, the following points should be considered
Use of a cement unit is preferable. This requires that either bulk barite be fed directly to the cement unit swell tank or that sufficient stocks of sacked barite be available at the carriage point.

Standard entrapments can be mixed to the asked viscosity with no problems of massive settling before displace

Oil Based Mud

Oil Mud Application

Barite draw settling rates in oil painting guck are typically dependent on the viscosity of the slurry and the type and attention of oil painting wetting down agents. Laboratory studies have shown that oil painting- grounded entrapments have a tendency to settle, on average, more sluggishly than water- grounded slurries.




At too low a attention of EZ MUL and DRILTREAT the barite is rightly oil painting-wet and isn't tone- suspending. At too high a attention the barite becomes extremely well suspended and the rate of settling is reduced. It's thus veritably important to precisely elect the optimum attention of EZ MUL for the draw viscosity needed.



still, use a slug hole or the reserve slush recesses, depending on the total volume of slurry needed, If a cement unit isn't suitable to mix barite. The length of the draw is a wellsite determination and should be grounded on the inflexibility of the situation. In utmost cases a draw in the range of 250 – 500 ft( 75- 150 m) is sufficient.

oil -Based Mud Procedure

Oil- grounded slush slurries can be mixed as follows

1. Transfer sufficient oil painting Grounded slush to the slug hole to maintain rotation through the mixing pump.
2. Fill the hole to half its capacity with a base oil painting and add roughly 4 lbs/ bbl(11.4 kg/ m3) EZ MUL and 4 lbs/ bbl(11.4 kg/ m3) DRILTREAT.
   
3. Weight up with barite to the needed viscosity; the hole should also be nearly full.
   
4. still, transfer the slurry formerly mixed to a reserve hole making sure that inciters are used constantly and another mixing pump put on to circulate that hole, If the total capacity of the slug hole is inadequate for the needed volume of the draw.
   

*To avoid the chance of initiating rapid-fire settling, inordinate additions of base oil painting aren't made at any stage.

*Small additions of over to1.5 lbs/ girl(4.3 kg/ m3) EZ MUL may be made to control density increases noted during barite additions.

*Barite addition rate is controlled in order to avoid inordinate increases in density or conceivably initiating settling.

Formulations for oil-base muds:

Water Based Mud

The formulation for one barrel of a 20 lbs/gal barite slurry is:

displacement

relegation ways are the same as in cementing; i.e., the slurry should be under- displaced so that the height of the slurry in the drill pipe is 2 bbls lesser than in the annulus. This allows the drill pipe to be withdrawn with a natural slugging action. It'll also minimize the movement of the slurry in the hole, reducing impurity.

Because of the high viscosity of these slurries, high differential pressures can be created by under orover-displacement. Care must be taken when calculating volumes. After the draw is spotted in place, tripping out of the hole should be done as snappily as possible and the draw allowed to settle for several hours. The well should be observed to insure there's no inflow. When tripping pipe back into the hole, the “ feeling ” for the draw should begin near the theoretical top of the draw.

Operations can also be started to set a cement draw above the barite, and the well can be safely secured.