G-SEAL Graphite Bridging Agent | Schlumberger


Sized graphite bridging agent

G-SEAL bridging agent is a coarse-sized plugging agent used in water-, oil- or synthetic-based drilling fluids to bridge and seal permeable and fractured formations.

When drilling depleted zones exposed to high differential pressures, the bridging and plugging capabilities of G-SEAL bridging agent can reduce the potential for stuck pipe. G-SEAL bridging agent is chemically inert and thermally stable and will not affect rheological properties when used at recommended concentrations. It can lower the potential for lost circulation and reduce torque and drag in many drilling applications.

Typical Physical Properties
 Physical appearance  Dark gray to black powder
 Specific gravity  2.19–2.26
 Solubility in water at 68 degF [20 degC]  Insoluble
 Median particle size (d50)  300–350 um

Median particle size is reported as a range because of variations in the manufacturing and grinding process. If a precise size distribution of a product is critical to a drilling operation, it should be measured with the appropriate recommended test procedure using samples that are representative of those expected to be used in that operation. Nominal d10 and d90 values are available upon request.


  • For seepage losses (<10 bbl/h [1.6 m3/h]): 15 to 20 lbm/bbl [43 to 57 kg/m3] in spotted pills or sweeps. G-SEAL bridging agent can be incorporated into the entire system at a total concentration of 5 to 10 lbm/bbl [14 to 29 kg/m3]. However, this may require using coarser shaker screens. If changing screens is impractical, pills returning to the surface can be diverted to a standby pit, reconditioned and reused as spots or sweeps.
  • For partial losses (10 to 100 bbl/h [1.6 to 16 m3/h]): 20 to 50 lbm/bbl [57 to 143 kg/m3] in spotted pills. Very high permeability formations such as fractured carbonates and conglomerates may require additional pills in combination with other lost circulation materials of appropriate particle size distribution. Torque and drag may be reduced by incorporating G-SEAL bridging agent spots and sweeps into the active system up to a total concentration of 10 lbm/bbl [29 kg/m3]. Initial treatments for the active system can be applied in 2-lbm/bbl [5.7-kg/m3] increments while monitoring torque and drag. G-SEAL bridging agent may require an additional wetting agent when used in an oil- or synthetic-based mud system.

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions described in the safety data sheet.

Packaging and storage

G-SEAL bridging agent is packaged in 55-lbm [25-kg] multiwall paper sacks. Store in a dry, well-ventilated area. Keep container closed. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.

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