Mud Balance

Mud Balance

The Mud Balance is used to determine the weight per gallon of the drilling fluid. It consists of base and graduated arm with cup, lid, knife edge, rider, level and counterweight. The cup is on one end of the arm and the counterweight on the other. Its use is by filling the cup level with a sample of mud taken as it comes from the bore of the well. It is then wiped clean, after placing lid, to remove excess mud from the outside.

There is a small vent hole in the lid. To be sure the cup is filled always make sure some fluid comes out of the hole as the lid is pressed into place. The balance is then placed upon knife edge rest. The rider is then moved until the instrument is in balance. The weight per gallon can then be read directly from the graduated arm.

To convert the weight per gallon to specific gravity we divide by 8.34. The weight of our fluid determines the pressure we place upon the formations. We only want the minimum pressures necessary to prevent formation caving. This should be in the range of 9 lb./gallon for most normal conditions. We must raise this weight when encountering high pressure formations to prevent their flowing during construction. This can be controlled by the addition of weighting agents to the degree necessary. It is important to note that this same instrument is used to determine the weight of our cement.