Benzoic acid diverter

Today, benzoic acid (flakes or fines) is probably the most broadly applicable diverter type, as it is soluble in water and oil and sublimes in gas. Benzoic acid may also be dissolved in water (as ammonium benzoate) and in alcohol. When contacted by water at reservoir pH, benzoic acid dissolved in either aqueous or alcohol solution is precipitated as a smaller, softer, and more easily deformed partide. This form of benzoic acid diverter may be used with more confidence in gravel pack completions, for example. 

Diverting agents assist in distributing acid more uniformly through the perforated formation interval (141). These are usually oil-soluble hydrocarbon resin particles. They may be dissolved by post-acid injection of xylene or similar solvents. Oil-soluble waxes, naphthalene, and solid organic acids such as benzoic acid have also been used (142). Best results are obtained using a broad range of particle sizes. 

The coupling of 2-iodobenzoic acid and phenylacetylene under Sonogashira coupling conditions was found to give a mixture of an isocoumarin derivative and a phthalide (4.40.), The proper choice of the catalyst system led to the preferential formation of the latter compound.53 The process might also be diverted towards the formation of the isocoumarin derivative by isolation of the intermediate o-cthynyl-benzoic acid and its subjection to carefully selected cyclization conditions54... 

Oil-soluble resin is not as popular as it once was but still has occasional application. Oil-soluble resin application is limited because its melting point is more than 300°F. Therefore, removal must be entirely from dissolution in produced oil. If that is not accomplished, a separate solvent treatment must be pumped to remove the diverter. Therefore, other degradable diverters, such as forms of benzoic acid and wax beads, are preferable because of their lower melting points (see table 6-9). 

Rock salt is still the chemical diverter of choice for routine HCl and non-HF treatments. Graded rock salt is the current embodiment. Combined particulates—graded rock salt and benzoic acid flakes, rock salt and wax beads, or benzoic acid and wax beads—can be effective. They can provide the benefits of a harder material and a softer, more malleable one, enhancing the temporary block created in perforations. 

Treatment placement or diversion in carbonate matrix acidizing is more difficult than in sandstone acidizing. This is because of the high solubility of carbonate formations in acid and the formation of channels. This eliminates the use of particulate diverters, such as rock salt, benzoic acid, and oil-soluble resin. 

---