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Line 84: − − [[file:rock-water-reaction-formation-damage_fig2.png|thumb|{{figure number|2}}Critical velocity determination with pH monitoring.]]
Rock-water reaction: formation damage (view source)
Revision as of 15:58, 7 April 2014
, 15:58, 7 April 2014→Salinity-related tests
===Salinity-related tests===
===Salinity-related tests===
[[file:rock-water-reaction-formation-damage_fig1.png|left|thumb|{{figure number|1}}Liquid permeability test indicating permeability reduction due to rock-liquid reaction.]]
Salinity-related tests furnish direct indication of rock-water interaction. They allow evaluation of damage induced by drilling, completion, workover, and injection fluids. [[:file:rock-water-reaction-formation-damage_fig1.png|Figure 1]] illustrates results of a laboratory experiment to evaluate the reaction to reservoir rock with a proposed injection brine. [[Permeability]] was reduced to 20% of its original value after exposure to 20 pore volumes of proposed injected brine. Good reservoir management requires that injected volumes equal produced volumes; therefore, reduced injectivity results in reduced hydrocarbon production rates.
Salinity-related tests furnish direct indication of rock-water interaction. They allow evaluation of damage induced by drilling, completion, workover, and injection fluids. [[:file:rock-water-reaction-formation-damage_fig1.png|Figure 1]] illustrates results of a laboratory experiment to evaluate the reaction to reservoir rock with a proposed injection brine. [[Permeability]] was reduced to 20% of its original value after exposure to 20 pore volumes of proposed injected brine. Good reservoir management requires that injected volumes equal produced volumes; therefore, reduced injectivity results in reduced hydrocarbon production rates.
When the source and composition of brine to be injected is unknown, water shock tests indicate potential rock damage and present a worse-case scenario. Permeability of the formation rock to a 0.51-''M'' (3 wt. %) NaCl solution is followed by permeability to freshwater. Sensitive rocks will show permeability reduction. Rock-water reaction must be evaluated for all aqueous fluids introduced into the reservoir system. Critical salinity (cation concentration) below which damage occurs, as well as schemes to lower brine concentration stepwise so as to avoid clay damage, can be evaluated in the laboratory.
When the source and composition of brine to be injected is unknown, water shock tests indicate potential rock damage and present a worse-case scenario. Permeability of the formation rock to a 0.51-''M'' (3 wt. %) NaCl solution is followed by permeability to freshwater. Sensitive rocks will show permeability reduction. Rock-water reaction must be evaluated for all aqueous fluids introduced into the reservoir system. Critical salinity (cation concentration) below which damage occurs, as well as schemes to lower brine concentration stepwise so as to avoid clay damage, can be evaluated in the laboratory.
===Rate-related tests===
===Rate-related tests===