natural bitumen Cementing Grade has a low specific gravity, is non-porous, and impermeable. The addition of natural bitumen to cement slurries reduces the slurry weight without requiring large additions of water. The result is a superior lightweight slurry, having good compressive strength, which is especially suited for cementing weak formations and in control of lost circulation.
Cementing Grade natural bitumen is available in bulk or 50 lb. net multi-ply paper bags, which may be palletized and stretch wrapped. It is also available in bulk loaded trucks and in a variety of bulk bag sizes.
Since natural bitumen, a solid hydrocarbon, was introduced to the oil industry in August 1957 as a cement additive, several thousands of jobs have been performed using the material. These operations have included primary cementing through lost-circulation zones of surface, intermediate, and production pipe in both single and multiple stages as well as various remedial jobs such as squeezing, re-cementing above inadequate fill-up, and plugging back to reestablish drilling-fluid circulation. Designed primarily as a combination low-density lost-circulation slurry, natural bitumen has yielded excellent results in areas of incompetent formations as well as in other types of lost-circulation zones. Field results generally show that fill-up of 80 to 90 percent can be obtained in areas where only 50 to 60 percent fill-up was possible with other types of slurries.
The unique properties of natural bitumen such as low specific gravity, particle-size distribution, impermeability, resistance to corrosive fluids, chemical inertness, and low water requirements result in a slurry having exceptional bridging properties, low slurry weight, compatibility with other slurry additives, and relatively high compressive strength when compared to other slurries of the same weight.
As the oil-producing industry has continued to grow, the need for a low-density cementing slurry possessing lost-circulation control characteristics has become more and more evident. This is especially so in primary cementing because of the different types of formations being encountered and the need to reduce remedial cementing operations. These problem formations may range from either porous or cavernous formations to very weak formations that are unable to support the hydrostatic head that is necessary for drilling and well completion. This latter type of formation will often break down or fracture under hydrostatic loading, resulting in partial or complete loss of circulation.