An operator developing tight carbonate reservoirs found that conventional acid stimulation with 15% hydrochloric acid (HCl) in horizontal wells did not provide expected results. A subsequent study revealed that permeability and length of treatment are the main parameters in deciding the optimal stimulation chemical. A correlation was developed, on the basis of the kinetic parameters of various chemicals and field experience, that can act as a guide in selecting the proper acidization formulations.
Introduction
In vertical wells, positive skin pertains to reduction of effective wellbore radius, thus sacrificing reservoir contact. It is very important to note that, in long horizontal wells, wellbore radius does not represent the reservoir contact; rather, it is replaced by the horizontal length.
