Gilsonite usage ER resins are “engineered resins”; the term “ER resin” or “Gilsonite ER resin”, as used herein, means a purified fraction of uintaite. These fractions are substantially enriched in maltenes or Asphaltens relative to natural uintaite. Merely dissolving uintaite in a solvent in which it is soluble (i.e., a solvent that dissolves greater than about 90% of the uintaite) and filtering this solution does not produce a purified fraction of uintaite as defined herein. Such a simple filtration process does not substantially change the asphaltene to maltene ratio from that of natural uintaite. Therefore it does not produce the asphaltene-enriched and maltene-enriched purified fraction of uintaite useful in this invention.
Gilsonite usage refers to the fraction of Gilsonite that is dissolved when finely ground gilsonite is contacted with 20 volumes of hot heptane at 80 solution is filtered through a 0.8 micron filter. Maltene-enriched fractions of gilsonite, such as ER-140 and ER-115, have a weight ratio of maltenes to asphaltenes of greater than about 6; preferably greater than about 15; most preferably these resins are substantially free of asphaltenes, i.e., less than 2 wt. % asphaltenes. Moreover these resins are also substantially free of ash.
Maltene-enriched ER resins as defined herein have softening points below about 140 relative to natural uintaite; they have at least 50% fewer asphaltenes than natural gilsonite, preferably at least 75% fewer, and more preferably at least 90% fewer. These maltene-enriched ER resins also have reduced mineral-derived insolubles, i.e., ash. These insoluble are below 0.1% by weight, preferably below 0.05%. The maltene-enriched fractions of uintaite useful in this invention comprise at least 60% maltenes, preferably at least 80% maltenes and most preferably at least 90% maltenes. Maltene-enriched ER resins have lower softening points than those of natural gilsonite. Solution viscosity, viscosity stability and melt viscosity are also substantially improved over available grades of Gilsonite. The less soluble, high melting, asphaltene-enriched fractions are also called ER resins.
Gilsonite can be used to lighten the slurry and increase the slurry yield but will still provide a relatively high-strength set cement. Large amounts of water are not required for gilsonite. The reduction of slurry density is primarily the result of the low specific gravity of the gilsonite.