Device for reclaiming and disposal of drilling wastes and method of use therefore

#This invention relates to systems and methods for disposing of waste fluids and solids and more particularly to such systems and methods for reclaiming drill tailings stored in pits.

#Oil and gas drilling operations produce drill cuttings or "tailings" that consist of material removed from a well with mixtures of other fluids and materials that are used to facilitate drilling. This other material is typically called drilling mud. In the past, the tailings and spent mud were pumped to open surface pits for storage. Current environmental rules regulate handling and disposal of the tailings that prohibit their disposal on the surface. To solve this problem, several methods of disposal have been developed. Recent examples may be found in U.S. Pat. No. 4,942,929 to Malachosky et al. and U.S. Pat. No. 5,109,933 to Jackson. The Malachosky et al. patent teaches a method for cleaning and removing commercial quantities of gravel that are recovered from wells drilled in northern Alaska. The method calls for making a slurry of the remaining material and then reinjecting this material back into the ground. The Jackson Patent uses centrifugal pumps to grind solids recovered from offshore wells. The ground solids are then mixed into a slurry and reinjected into the well for disposal. Both inventions are designed for specific, narrowly designed purposes. They are not designed to treat large quantities of solid materials that may be frozen, such as material stored in many above-ground reserve pits found in the polar regions. Moreover, these devices cannot dispose of large quantities of material.

#The present invention provides a method of removal and disposal of this general type of solid waste material. The present invention is designed to dispose of frozen reserve pit material, thawed reserve pit material and soils contaminated with low level radiation or other pollutants.

#FIG. 1 is a schematic representation of the major system components and the material flows between them.

#FIG. 2 is a detailed schematic of the injection system components.

#FIG. 3 is cross sectional view of the slurry tank.

#In the description that follows, and in the drawings, certain features and elements that are commercially available or are of conventional construction are described only in general terms and are shown in schematic form in the interest of clarity and conciseness.

#Referring now to the drawings, waste materials 1 are held in a reserve pit 2. These materials include gravels, soils and clays removed from a well drilling operation or may consist of contaminated soils that are trucked into an area for disposal. In a well drilling operation, the mixture will also contains components of drilling mud, a composite material used to help the drilling process. In the drilling operation this material has been typically dumped into the reserve pits 2, that are dug into the ground nearby the well site. These pits 2 are typically open and exposed to the elements. Some materials placed in these pits 2 are now considered to be hazardous wastes, requiring special handling, or below-surface disposal. One problem encountered is that this material is viscous and often forms large clumps, making pumping and, therefore, down hole disposal, difficult. Moreover, in northern climate zones, such as Alaska, these pits become frozen in the winter making treatment and disposal even more difficult.

#To remove frozen material from the pit 2, in the preferred embodiment, chippers are used to break out the material in chunks. Alternatively, the material may be thawed using steam or a limited amount of hot water, which can be injected directly into the reserve pit 2.