Changes

====Salinity-related tests====

====Salinity-related tests====

[[File:RWRFigure1.png|thumbnail|Liquid permability test indicating permeability reduction due to rock-liquid reaction.]]

[[File:Rocks.jpg|thumbnail|left|Figure 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]]. [[:Image:RWRFigure1.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]]. [[:Image:rocks.jpg|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.

Capillary (water retentive) properties of rocks are altered by rock-fluid reactions. Capillary curves before and after exposure to extraneous fluids indicate if rock-fluid reaction has reduced pore sizes. If reduction occurs, retained water saturation is increased. <ref name=Amaefule_etal_1986>Amaefule, J. O., K. Wolfe, J. D. Walls, A. O. Ajufo, and E. Peterson, 1986, Laboratory determination of effective liquid permeability in low-quality reservoir rocks by the pulse decay technique: 56th California SPE Regional Meeting of the Society of Petroleum Engineers, Oakland, CA, April 2-4, [[spe:15149|SPE paper 15149]], p. 493-502.</ref>

Capillary (water retentive) properties of rocks are altered by rock-fluid reactions. Capillary curves before and after exposure to extraneous fluids indicate if rock-fluid reaction has reduced pore sizes. If reduction occurs, retained water saturation is increased. <ref name=Amaefule_etal_1986>Amaefule, J. O., K. Wolfe, J. D. Walls, A. O. Ajufo, and E. Peterson, 1986, Laboratory determination of effective liquid permeability in low-quality reservoir rocks by the pulse decay technique: 56th California SPE Regional Meeting of the Society of Petroleum Engineers, Oakland, CA, April 2-4, [[spe:15149|SPE paper 15149]], p. 493-502.</ref>

The critical interstitial velocity at which permeability reduction due to fines migration is initiated can be determined in laboratory tests. These tests simulate the effect of [[high flow rates]] that exist near the wellbores of both injection and production wells. Muecke (1979)<ref name=Muecke_1979>Muecke, T. W., 1979, Formation fines and factors controlling their movement in porous media: Journal of Petroleum Technology, v. 31, p. 144-150.</ref> discusses factors controlling fines movement. These include fluids flowing, fines [[wettability]], and interfacial forces.

The critical interstitial velocity at which permeability reduction due to fines migration is initiated can be determined in laboratory tests. These tests simulate the effect of [[high flow rates]] that exist near the wellbores of both injection and production wells. Muecke (1979)<ref name=Muecke_1979>Muecke, T. W., 1979, Formation fines and factors controlling their movement in porous media: Journal of Petroleum Technology, v. 31, p. 144-150.</ref> discusses factors controlling fines movement. These include fluids flowing, fines [[wettability]], and interfacial forces.

[[File:RWRFig2.png|thumbnail|Critical velocity determination with pH monitoring]]

[[File:Charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_4.jpg|thumbnail|Figure 2: Critical velocity determination with pH monitoring]]

[[:Image:RWRFig2.png|Figure 2]] illustrates laboratory data that established a critical flow velocity of 0.3 cm/sec. Beyond this rate, fines were mobilized that bridged at pore throats and resulted in reduced permeability. The pH of the [[effluent]] was monitored throughout the test. The constant pH value indicated that no chemical reaction was occurring between the rock and fluid and that viscous forces were the cause of the reduced permeability.

[[:Image:Charles-l-vavra-john-g-kaldi-robert-m-sneider_capillary-pressure_4.jpg|Figure 2]] illustrates laboratory data that established a critical flow velocity of 0.3 cm/sec. Beyond this rate, fines were mobilized that bridged at pore throats and resulted in reduced permeability. The pH of the [[effluent]] was monitored throughout the test. The constant pH value indicated that no chemical reaction was occurring between the rock and fluid and that viscous forces were the cause of the reduced permeability.

The critical flow velocity is normally obtained by testing a cylindrical sample, with flow parallel to the linear axis. The linear velocity can be scaled to the radial flow condition existing in the wellbore. The scaled data yield the maximum [[well flow rate]] in barrels per day that can be tolerated before fines bridging and loss of production rate occurs.<ref name=Gorman_etal_1989>Gorman, I., C. Balnaves, J. Amaefule, D. Kersey, and D. Manning, 1989, Gravel packing in poorly lithified reservoirs: Laboratory systems approach to aid decision-making strategies: Society of Petroleum Engineers Paper No. 19477.</ref> These data allow calculation of the radius of the permeability impaired zone and aid in sizing subsequent acid volumes required to clean up the impairment.

The critical flow velocity is normally obtained by testing a cylindrical sample, with flow parallel to the linear axis. The linear velocity can be scaled to the radial flow condition existing in the wellbore. The scaled data yield the maximum [[well flow rate]] in barrels per day that can be tolerated before fines bridging and loss of production rate occurs.<ref name=Gorman_etal_1989>Gorman, I., C. Balnaves, J. Amaefule, D. Kersey, and D. Manning, 1989, Gravel packing in poorly lithified reservoirs: Laboratory systems approach to aid decision-making strategies: Society of Petroleum Engineers Paper No. 19477.</ref> These data allow calculation of the radius of the permeability impaired zone and aid in sizing subsequent acid volumes required to clean up the impairment.