Paper: A New Non-Damaging, Aqueous Crosslinked Gel With Improved Fracturing Properties And Perfect Proppant Support

This paper will discuss the properties and applications of a new water-base fracturing fluid. In particular, it will discuss its leak-off characteristics, its rheological behavior, and its proppant-transport capability. Additionally, it will give examples of its use in the field, including production information. Beginning in the late 1960"s, intensive research was done in the area of improved stimulation fluids. This led to the development of a variety of crosslinked fracturing fluids based on both organic and synthetic polymers. These fluids featured extreme viscosities, perfect or near perfect proppant transport, and good pumpability without excessive friction drop. In nearly all cases, high polymer loadings were required for optimum performance. In the case of the natural polymers, the higher loadings resulted in excessive residue and consequent sand-pack damage. The synthetic polymers left no damaging residue; however, they were prohibitively expensive. The subject gel was designed to overcome the limitations of the early crosslinked gels. It features a moderate polymer loading which, when complexed with an organometallic chelate, furnishes high but not excessive viscosity combined with perfect proppant transport. It features good leak-off control and is residue-free when broken. The base polymer of this system is carboxymethylcellulose which is hydrated prior to pumping. The complexing agent is added continuously after sand is dispersed in the base gel. Since the concentration of organometallic chelate is low, an air-drive proportioner ha's been designed and built with suitable control and monitoring features. This device is also described in the paper.