Four Major Functions of Filtrate Reducer

Apr 23, 2014

READ: Pressure gradients naturally genders fluid loss through the walls from the drilling mud as drilling processes, subsequently developing into borehole collapse and drilling-related accidents. Thus, filtrate reducer plays a significant role in maintaining relatively low fluid loss, one of the essential properties of the mud.

Pressure gradients naturally genders fluids loss through the walls from the drilling mud as drilling processes. Excessive fluid loss can impact many aspects of drilling operations:

1. Shale formation can expand and collapse and the wall be less stabilized.

2. Fluid penetration can expand the clay, blocking the oil and gas channel and damaging the formation.

3. Larger fluid loss thickens the filter cake, narrows the borehole diameter, increases the torque of drilling rig, hinders “going in”, weakens cementing quality, etc.

The above can subsequently develop into borehole collapse and drilling-related accidents.

I. It works as a protective colloid.

Filter cake of low permeability involves proper size distribution of clay particle diameter and more fine particle content in drilling mud. Then,

1. Filtrate reducer can form an adsorbed layer covering the clay particle and stop it from flocculation.

2. Filtrate reducer can stabilize the particles agitated in circulating system and prevent formation of bigger particles. Thus, larger proportion of fine particles will produce finer filter cakes.

II. It increases fluid density and shrinks fluid loss.

Generally, fluid loss is reversely proportional to fluid viscosity to the power of 0.5. Organic filtrate reducer can bring the viscosity up and fluid loss down.

III. It deepens the hydration of bentonite particles in drilling mud.

In this way, it can lower the fluid loss. When it attaches itself on the clay particles, they are more hydrated and their hydrated shell thickened. Besides, the filter cake thereof is more prone to deformation at high pressure and thus made less permeable.

IV. Its molecules are able to block the holes.

Organic high-molecule filtrate reducer, smaller than colloidal particles, can, on one hand, well fit molecular chains into filter cake’s cracks, and on the other hand, block micro holes with curled long molecular chains, creating thin and fine cake to reduce the loss.