Mud gun are meant to provide supplemental or primary mixing in mud tanks depending on the number being used and the pit size. They are best used in tank corners to keep solids from settling and a mud agitator is placed in the tank center.
Mud guns are to be located in the tank corners. The centerline of the nozzle is to be located about 6″ off the tank bottom.
The mud agitators are high-efficiency mud-mixing units offered in a wide array of custom sizes and configurations to accommodate virtually any mud tank. Both horizontal and vertical drive configurations are available for all sizes of mud agitators. The horizontal drive is designed for installations having limited space above the mud tank.
The mud agitator stirs a mud slurry to maintain suspension of solids. The agitator is mounted on top of the mud tank and has one or two impeller(s) immersed in the mud slurry. The impeller shaft is directly coupled to an electric drive motor that is available in several horsepower ratings from 3 (50Hz only) to 30 (60Hz). Impellers are available in diameters ranging from 20″ to 52″ to meet the needs of various size mud tanks.
The mud agitator is operated by a 3-phase induction motor. Drive motors range from 5 to 30 horsepower for the 230/460Vac 60Hz power configuration and 3 to 25 horsepower for the 190/380 50Hz power configuration.
Design of shaft-Blade assembly
Though there are mud guns and mud agitator‘s, to activate the mud, there is certain portion in the mud tank which is not influenced by these activating devices. Hence this portion of mud tank is having in-activated mud. This in-activated mud promotes in settling of the chemicals at the bottom of the tank creating a differential chemical composition throughout the tank. This in-activated mud is carried to the drill string followed to the drill bit, where its functioning is severely affected. On observation, in mud tank there‘s a provision to run a horizontal shaft-blade assembly through the length of the tank. Such an arrangement at proper elevation can activate that portion of the tank which is generally a dead zone. This assembly runs horizontally along the length of the mud tank with three bearing supports at the partition. Each blade assembly consists of four blades and four such assemblies are located through out the length of the shaft.
On economic considerations, the amount of chemicals wasted due to this in-active mud is primarily calculated. The cost of chemicals wasted per tank for a location is amounting to around Rs.51,000/- (Rs. Fifty one thousand). If the drilling rig, works at least for a span of one year in five locations, the total cost of chemicals lost amounts to Rs.2,55,000/- (Rs. Two lakh fifty five thousand). To reduce this wastage of mud it is proposed in this paper to design a horizontal shaft-blade assembly
Once the economic aspects are cleared the design of the shaft-blade assembly is taken into consideration.
This paper emphasizes on three aspects.
1. Design of shaft.
2. Design of blade.
3. Economic aspects of chemicals wasted and cost of equipment.
But before getting into the complete design, the following design criterion need to be noted.
Mud with density 1668.1 kg/m3 is chosen in order to design the project for high mud weight. The Standard D.C Motor with speed reduction gear box used to mud-agitator is selected for calculation towards failure criterion.
The total provision for the assembly to accommodate w.r.to Length x Width x height is taken into consideration. With which the size of shaft and blades are primarily considered.