Changes

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

[[File:Rock-water-reaction-formation-damage fig2.png|thumbnail|'''Figure 2.''' Critical velocity determination with pH monitoring]]

[[: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.

[[:Image:Rock-water-reaction-formation-damage fig2.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.

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.