Summary of Mud’s Composition and Resultant Functions

Apr 25, 2014

READ: Drilling fluids, the circulating fluid for drilling operations, is a mixture of the fluid, the solid and chemical agents. It is usually known as the “mud” or the “blood of drilling” deriving from its distinctive significance.

Drilling fluids, the circulating fluid for drilling operations, is a mixture of the fluid, the solid and chemical agents. It is usually known as the “mud” or the “blood of drilling” deriving from its distinctive significance.

The solid in mud primarily includes concocting clay, weighting materials, drill cuttings and other solid substances. In terms of sources, it then comprises concocting clay, debris, weighting materials, solids from agents, etc.

Besides, different types of action of solids and ions in water can further categorize low-density solids into active and inert ones.

Active solids: Active solids tends to hydrate or react with other solids in the mud, They have higher surfactivity, larger specific surface area and more active electrochemical properties. And usually a closer unity exists between clays, clay and ions, clay and polymers. Active solids are also known as useful solids for their roles in mud property adjustment.

Inert solids: Inert solids refer to such inactive solids without any surface charge or possibility of electrochemical reaction as sands, flints, limestones, dolomites, some shales and various mineral mixtures. When they integrate, they can improve the mud properties by compressing active solids and increasing the viscosity, However, Inert solids are usually of no use, which another name“useless solids”derives from, and are corrosive to circulating equipment when the diameters are beyond 15μm, thus they are also known as harmful solids.

Rock cuttings, the major harmful solids in mud, can exert great influence on the mud properties as they add to the density, viscosity, yield point, water loss, abrasiveness, treacliness and flow resistance, and can trigger various bore hole complications like damage of formations, reduction of drilling velocity, increase of table torque, resistance of each trip, sticking drilling, leakage, blowout, etc.