Several techniques for the real-time evaluation of matrix acidizing have been presented over the years.1,2,3  All rely on the calculation of the skin factor of the formation during the course of the treatment as the indicator for treatment effectiveness.

Two general approaches are currently used for calculating the skin factor of a well during a matrix acidizing treatment. The first assumes that a steady-state flow regime is in effect during injection while the second uses a pressure transient solution to calculate the skin factor during the treatment and assumes the well is in an infinite-acting transient flow regime. Comparisons of both calculation methods will be presented in this paper as will the advantages and limitations common to both methods. Also presented are two field case histories in which a pressure transient solution was used to continuously monitor the skin factor during the treatments. These case histories show in detail the effect of the different fluid stages injected during the treatments, including the effect of diversion stages. The concept of using the derivative of the skin factor with respect to time to track the rate of damage removal during acid injection or the rate of skin factor increase during diversion stage injection is also introduced.

You can access this article if you purchase or spend a download.