QUANTIFYING ACID PLACEMENT - THE KEY TO UNDERSTANDING DAMAGE REMOVAL IN HORIZONTAL WELLS

The placement of acid over the entire wellbore interval can be the key to successful stimulation treatments in wells with long (often horizo ntal) completion intervals. In this paper, we discuss computer simulat ions performed to determine how fluids are distributed in the wellbore during acidizing treatments. One of the novel aspects of these simula tions is the inclusion of wellbore effects arising from the transient flow of acid and diverter along the wellbore. The results suggest a po ssible cause of some of the poor stimulation performances observed in the field when acid was injected without diversion or selective-placem ent techniques. Such situations can result in the acid contacting only a small fraction of the treatment interval. The simulations also show how making the acid viscous could have improved the stimulation perfo rmance.