With the advent of the development of lower Tertiary formations in the deepwater Gulf of Mexico, a gap in proppant technology was identified at the beginning of the decade. No existing conventional proppant could provide the required conductivity at the anticipated 15,000 psi (and higher) prevailing closure stress. To meet these challenges a new proppant was developed, with the goal of achieving twice the baseline conductivity of any conventional proppant at 20,000 psi.
Improvements in the manufacturing process lead to the required superior performance needed in extreme depth and stress environments. The shape of the new Ultra-High Stress Proppant (UHSP) is highly round and spherical with a mono-sized sieve distribution. At higher stresses, this means the UHSP will provide higher proppant pack porosity and ultimately more space to flow. In addition, the surface of the proppant is very smooth, leading to lower Beta, as well as reduced erosion potential. An extremely low internal pellet porosity evenly distributed in fine pores results in much stronger grains, with crush value of less than 2% at 20,000 psi for 20/40 mesh equivalent product. Additionally, the new proppant technology provides further advantages with increased durability and longevity, as well as significantly reduced erosion on downhole tools and equipment.
Further to the ultra-high stress applications the new manufacturing technique was applied to ores typically used to manufacture low density ceramics. The result is a proppant with equal or better conductivity than standard intermediate and high density ceramics leading to larger frac volume and better carrying capacity. This new low density ceramic can effectively replace the use of conventional ceramics from low to medium and high stress applications and in many cases reduce the costs associated with pumping these higher density proppants.
This paper will briefly review the manufacturing process and resulting step change advancements achieved by this new proppant, stressing on the technology adoption in the Gulf of Mexico illustrated with multiple case histories. This paper should be beneficial to all engineers and technologists currently working in fracturing applications from low to ultra-high stress, or other harsh conditions such as steam-flooding and geothermal applications.