1. n. [Drilling Fluids]
Mathematical relationship between the densities and the corresponding volumes of mixtures of liquid-solid slurries and clear fluid blends, such as drilling muds and completion fluids. Assumptions are: (1) masses and volumes of components are additive and (2) material is neither generated nor lost from the system. As a simple example, below are the two material-balance equations for a three-component mixture of oil (o), water (w) and solids (s), where V = volume percent, D = specific density and MW = mixture weight. (This could represent a simple, weighted oil-base mud formulation.)
MW = DsVs + DoVo + DwVw
100% = Vs + Vo + Vw.
See: high-gravity solids, low-gravity solids, make-up water, mass balance, mud density, retort solids, slurry