For many years, Gilsonite has been used in the oilfield as an additive in drilling fluids. Gilsonite, in various grades and formulations, has been used to combat borehole instability problems, provide lubricity, especially in highly deviated holes, and more recently as a bridging agent to combat differential pressure sticking and provide a law invasion coring fluid. It has been well documented that appropriately formulated Gilsonite products can minimize hole collapse in formations containing water-sensitive, sloughing shales and reduce stuck pipe problems by forming a thin wall cake and an inter-matrix filter cake.
Gilsonite products are currently being widely used in water based, oil based, and synthetic based mud systems worldwide. Blended Gilsonite has proved to be very effective in all water-based systems.
The role of drilling mud
- Cleaning of wells and transporting carcasses to the ground.
- Placing the wall and preventing it from slipping into the well and preventing the drilling mud filter from entering and causing damage to the tank.
- keeping the drill bit cool and clean during drilling.
- Oil drilling and drilling pipes.
- Control of underground pressures.
- Floating drilling rigs and fluid weight gain materials when pumps are off to prevent sedimentation, which can lead to drilling blockage and eventually residual or loss of wells.
- Hydraulic power transfer of pumps to drill by jet impact mechanism.
- Reduce waste on adjacent formations.
The main functions of drilling fluids include providing hydrostatic pressure to prevent formation fluids from entering into the well bore.
There are basically three types of drilling muds:
- Oil based Muds (OBM): Base material is Oil product, such as diesel oil
- Water Based Muds (WBM): Base material is water
- Synthetic Based Muds (SBM): Base materials is polymers
In oil-based muds, Gilsonite acts as a Fluid loss control agent or FLC. While as a hydrocarbon, it reacts well with the base material of the mud and increases the drilling efficiency significantly. Also, since Gilsonite has a high softening point, applying Gilsonite will significantly reduce the loss of fluids.
Gilsonite improves drilling efficiencies, wellbore stability, filter cake development and more.as an integral component of premium drilling fluid products, Gilsonite actively improves drilling efficiencies while reducing costs and minimizing the HSE impact associated with most drilling fluid additives. Being a hydrocarbon, it is naturally wetted by the oil. In water-base muds, it is used as a shale-stabilizing additive and is difficult to evaluate unless tested at or above its softening point.
Fluid loss control: The act or means of controlling (usually lowering) the volume of filtrate that passes through a filter medium. Control of fluid loss for a mud is achieved by several means, one of which is by addition of fluid-loss-control materials for example Gilsonite to the mud system.
Use of FLC (Gilsonite) in fluid loss control system
Gilsonite fluid loss additive has been added to drilling fluids to give better stability of well walls, to lubricate the drill string in a well, to seal micro fractures and thus prevent the formation of larger fractures and to decrease the loss of filtrate to formations at high temperatures.
The use of FLC in drilling fluid dispersions or muds, to coat the walls of well holes, is an old and well-established procedure. The purpose of the fluid is to stabilize the walls of the hole by forming a relatively thin but strongly adherent coating or cake on the walls. The coating must be able to withstand relatively high temperatures and it should be resistant to the passage of moisture or fluid there through.