Acid fracturing physics

A property not listed in Table 5.14, but which is of paramount importance to this application, is wear rate. Wear rate was described briefly in Section 8.2.2, and those concepts apply here as well. As it applies to tooth enamel, abrasive wear occurs by fracture or chipping of the enamel, chemical erosion, which may arise due to acidic medications or drinks, dietary oxalate, or high oral hydrogen ion concentrations as a result of disease, physical erosion, or abrasion, which arises due to idiopathic mechanisms, dentrifices, toothbrushes, or abrasive diets. For example, the wear rate of enamel has been measured at about 10 ttm/hour due to brushing with a toothbrush and toothpaste for 86,400 strokes [7],... 

In another medical situation, osteogenesis imperfecta, supplementation with vitamin C at a level of 1-2 g/d (to subjects with ascorbic acid levels in the normal range) resulted in increased physical activity and stamina, and in reduced fracture incidence (57). These findings remain to be confirmed. 

Silicone and butadiene/acrylonitrile elastomers have been successfully incorporated into an addition polyimide adhesive LARC-13. Two approaches were used to accomplish this task. Fluorosilicone (Silastic) and vinyl-terminated (Sylgard) silicone rubbers were physically blended into the adhesive amic acid and aromatic ATBN and aromatic amine-terminated silicone elastomers were chemically reacted into the prepolymer backbone. Each of the four resins displayed a distinct and separate Tg for the resin and elastomer phases. Incorporation of elastomer particles at a concentration of 15% by weight solids resulted in a 6- to 7-fold increase in peel strength and a 3- to 5-fold increase in the fracture toughness of LARC-13. This improvement in toughness was accomplished at a sacrifice in the elevated temperature adhesive strength of the material. 

The physics of carbonate acidizing is complex, with respect to both fracture and matrix acidizing. 

Leak-off is more severe in formations with high permeability and in gas wells (high reservoir fluid capacity). Leak-off occurs through acid-created channels, or wormholes, branching off from the fracture to the matrix. Leak-off can be partially controlled by reducing wormhole creation (through acid retardation) or physically blocking those wormholes that are created. 

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