John R. Hellmann
The goal in hydrofracturing and stimulation of gas and oil wells is maintaining high permeability paths for resource recovery over the life of the well. This is commonly achieved by introducing a slurry of surfactants, corrosives, and ceramic aggregates into the fractures emanating from the well bore after the hydrofracturing process. The aggregates are then pinned by closure stresses after the well pressure has been relieved, and "prop" the fracture open, thereby providing a permeable pathway for oil and gas to migrate to the well bore for subsequent extraction. Hence, the aggregates are commonly referred to in the industry as proppants.
State of the art proppants are derived from sintered aluminosilicates, such as kaolin and bauxite. However, the demand for high alumina content aluminosilicates fro primary aluminum metal production and for use in industrial refractories has increased nearly six-fold worldwide in the past several years, resulting in a significant shortage, accompanied by a concomitant increase in cost of high strength proppants.
Research funded by the Stripper Well Consortium this past year at Penn State demonstrated that an alternative raw material, mixed glass cullet from the domestic glass recycling stream, could be processed into the form of proppants which rival commercially available sintered bauxite based materials with regard to strength, hardness, and specific gravity. Through the use of a novel molten salt ion exchange process, the glass proppants could be manipulated to fail in a manner that should promote long term retention of high fluid permeability in gas and oil bearing shales and tight sands.
This work has attracted a substantial amount of interest in the oil and gas industry, where significant growth in demand for proppants is anticipated in the near future. Manufacturing proppants from a domestic waste stream (mixed glass cullet) offers a lower cost, more readily available alternative to proppants manufactured elsewhere. Several firms are currently seeking to license the technology for application in hydrofracturing. However, we are not yet able to manufacture the materials in sufficient quantities for evaluation using industry-accepted crush and permeability tests (API 60 and 61) prior to deployment in a hydrofractured well.
Therefore, this proposal addresses continuation of the work to manufacturing the materials in a large enough quantity (hundreds of pounds) to permit a comprehensive evaluation of their utility as proppants using accepted American Petroleum Institute test methods. This will enable the deployment of the technology in deployment several rapidly emerging unconventional energy reserves.