Shale Stabilization with Gilsonite

Shale instability is one of the most expensive problems in drilling. Swelling, sloughing and caving shales can cause stuck pipe, tight hole and lost time. Gilsonite helps stabilize shale by physically sealing it.

Why shales fail

Shales contain clays and micro-fractures. When mud filtrate enters, pore pressure near the wellbore rises, clays hydrate and the rock weakens.

Mechanical sealing

Deformable gilsonite particles enter micro-fractures and bedding planes and plug them. This slows pressure transmission and filtrate invasion, keeping the near-wellbore rock stronger.

Chemical and mechanical approach

Gilsonite works best alongside chemical inhibitors such as potassium chloride, glycols or amine inhibitors. The inhibitor reduces clay hydration; gilsonite reduces the volume of water reaching the clay.

Signs that gilsonite is working

• Firmer, sharper cuttings
• Less cavings on the shakers
• Smoother trips and lower torque

Water-based systems

In water-based mud, sulphonated asphalt is a convenient water-dispersible option.

Laboratory evaluation

Field tips

• Start treatment before entering reactive shale.
• Maintain concentration as it is consumed on cuttings.
• Monitor shaker cuttings shape and size.

Learn more about sulphonated asphalt vs. gilsonite, or see our drilling fluid grade gilsonite.