We have devised a new procedure for synthesizing fulvenes from indene and fluorene using phase-transfer catalysis. Compounds synthesized include the benzhydrylidene derivatives of fluorene and indene and the benzylidene derivative of fluorene.Cyclopentadiene reacts readily with aldehydes and ketones in alkaline solution; indene reacts only under more stringent conditions; and fluorene reacts only as the Grignard, sodium, or lithium derivative (1, 2). By using solid sodium hydroxide and a phase-transfer catalyst, tetrabuty-

Includes synthesis of an aldehyde from a primary alcohol as well as several ketones from secondary alcohols.

This paper presents case histories showing that operators drilling in eastern states have increased oil and gas production by reducing the amount of guar polymer used to stimulate a well. The fluid system used in the 80 to 140 F applications in the region is a 20- to 25-lbm/Mgal guar with a buffered borate crosslinker that provides an instant crosslink. The wells being treated as described are shallow, and rapid complexation is needed to ensure proppant transport through the perforations. Laboratory test results are also presented. Rheology and sand transport for the optimized fluid system are compared to similar properties of conventional borate-crosslinked fluids. In general, fluid properties of the low-guar polymer compare to properties of conventional borate-cross linked fluids containing polymer concentrations 5 to 15 lbm/Mgal greater. Viscosity and fluid-efficiency values of the low-guar system (25 lbm/Mgal) compare to a 35-lbm/Mgal conventional borate-crosslinked fluid. Because reservoir cleanup after fracturing is an important component of production, production increases seen in these wells are mainly attributed to the lower gel loading used. P. 197

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The stability of polysaccharide gels at high temperature is limited by such factors as pH, mechanical degradation, and oxidants. Oxygen is unavoidably placed in fracturing fluids through dissolution of air. To prevent premature degradation of the fracturing fluid by this oxidant, oxygen scavengers are commonly used. In this paper, the effects of oxygen and various oxygen scavengers on gel stability will be presented. Mechanical removal of oxygen resulted in surprisingly stable fracturing gels at 275 F. However, chemical removal of oxygen gave mixed results. Test data from sodium thiosulfate, sodium sulfite, and sodium erythorbate used as oxygen scavengers/gel stabilizers showed that the efficiency of oxygen removal from gels did not directly coincide with the viscosity retention of the gel, and large excesses of additives were necessary to provide optimum gel stabilization. The inability of some oxygen scavengers to stabilize the gel was the result of products created from the interaction of oxygen with the oxygen scavenger, which in turn, produced species that degraded the gel. The ideal oxygen scavenger should provide superior gel stabilization without creating detrimental side reaction products. Of the materials tested, sodium thiosulfate appeared to be the most beneficial. Introduction Polysaccharides used in the preparation of fracturing fluids degrade in solution, resulting in premature loss of fluid viscosity and reduced efficiency of the fluid to create the fracture, maintain fracture width, control leakoff, and transport proppant. The fluid viscosity loss is directly associated with the reduction of the polymer size in solution. The molecular weight of a polymer can be reduced through several methods: acid-catalyzed hydrolysis, oxidation, enzymatic action, and mechanical shear degradation. Acid-catalyzed hydrolysis of the connective bonding, a glycosidic linkage of polysaccharides, is a well-documented phenomenon that serves as a basis for the commercial processes that produce various molecular weight fractions from the polymer. The polysaccharide backbone's degree of degradation is dependent on acid concentration, duration, and temperature. This process is the mechanism by which fluids made from guar (a polysaccharide) prematurely lose viscosity in downhole fracturing operations. P. 339