Double porosity reservoirs, damaged

In damaged double porosity reservoirs, the influence of the fractal dimension df is masked by the severity ratio kpp/kpp (Equation 12). ... 

The actual response of Well A to the injection of acid cannot fit with any kind of theoretical equation for undamaged primary porosity or damaged double porosity reservoir. Therefore, the acid attack in secondary porosity formations proceeds very differently, as expected. 

Figure 1 Permeability profile in a damaged double porosity reservoir during acidizing. rw wellbore radius, re wormholes penetration, damage radius, kptp undamaged reservoir permeability (total contribution of both primary and secondary porosities), kPP damaged permeability (primary porosity contribution only).

Actual responses of tuo carbonate petroleum reservoirs to matrix injection of hydrochloric acid are compared with a recently proposed experimental model for wormholing. This model is shown to be applicable in undamaged primary porosity reservoirs, and should be useable in damaged double porosity ones. Formations of no primary porosity are shown to respond very differently. 

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