ABSTRACT
Formation damage in the vicinity of the wellbore is a major cause of low productivity, and the difficulties involved in removing the damage translate into a significant number of wells that do not respond satisfactorily to remedial treatment. This damage is usually the result of fines migration which is triggered by the introduction of foreign water. The migrating fines tend to lodge in constrictions in the formation flow channels where they severely reduce production.
Clay stabilizers have been used to solve this problem for several decades. Cationic organic polymers (COPs) have been the most popular stabilizers because of treatment longevity and effectiveness in moderate to high permeability formations. Most producing formations in the United States, however, do not have moderate to high permeabilities but are classified instead as "low" permeability.
A new clay stabilizing additive has been developed specifically for low permeability formations typical in the Appalachian basin. This low molecular weight chemical is shown to be effective in rock matrices with permeabilities as low as 0.015 md. Other popular clay stabilizers with higher molecular weights are less effective in preventing swelling and migration of clay in formations having permeabilities below 30 md. Additionally, permeability damage can result when these relatively high molecular weight polymers are injected into low permeability formations.
Data are included from laboratory core tests using the low molecular weight clay stabilizer. The encouraging results of these laboratory tests is supported by field production results in the Appalachian basin. The field data include the results of fracturing, acidizing, and other operations, all of which are tabulated and discussed.
