High-resiliency graphite bridging agents

Schlumberger Oilfield Services

G-SEAL HRG and G-SEAL HRG FINE high-resiliency graphite bridging agents provide enhanced bridging and sealing of natural or induced fractures and for drilling permeable formations.

Both are compatible with water-, oil-, and synthetic-based drilling fluid systems. They also can be used to control seepage in partial to severe lost circulation zones.

Completely inert, the bridging agents do not affect the rheological properties of the fluid. They have the capacity to increase lubricity, thereby reducing torque and drag. Plus, permeability plugging tests and sand bed laboratory studies have proved that they exhibit lower spurt and total filtrate loss values.

 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 (d50) is reported as a size 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. The pills can be incorporated into the entire system for a total concentration of 5 to 10 lbm/bbl [14 to 29 kg/m3]. When the pill returns to the surface, the shaker screens must be monitored for losses and changed if necessary. If changing shaker screens is impractical, once the pill returns to surface, it can be diverted to a standby pit, reconditioned, and reused as a spot or sweep.
  • For partial losses (10 to 100 bbl/ [1.5 to 15 m3/h]: 20 to 50 lbm/bbl [57 to 143 kg/m3] in spotted pills. Highly permeable formations such as fractured carbonates and conglomerates may require additional pills in conjunction with lost circulation materials of various sizes. The product(s) also can be incorporated into the entire system for a total concentration of 5 to 25 lbm/bbl [29 to 70 kg/m3].

Torque and drag can be reduced by incorporating G-SEAL HRG or G-SEAL HRG FINE 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 may be applied in 2-lbm/bbl [5.7-kg/m3] increments while monitoring torque and drag.

The bridging agents may require additional wetting agents when used in an oil- or synthetic-based drilling fluid systems.

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 HRG and G-SEAL HRG FINE are packaged in 50-lbm [22.7-kg] multiwall paper sacks. Store in a dry, well-ventilated area. Keep container closed. Store away from incompatibles. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.