The Impact of Acidizing on Carbonate and Sandstone Reservoirs

الملخص

Formation damage is the impairment of permeability of rocks inside a petroleum reservoir. Near wellbore formation damages have a great impact on productivity index. Acidizing is a stimulation method to remove the effect of the damage through reacting with damaged materials to restore or improve permeability around the wellbore. Acid can be injected into the damaged formation below the fracture gradient of the formation which is called matrix acidizing. Acidizing operations is not only for treating the damaged formation, but also could be used for cleaning wellbore, production tubing and perforations from deposited scales, The main objective of this study is to evaluate the impact of acidizing on couple of Libyan fields for Libyan Oil and Gas Company, PROSPER Software was used to estimate productivity index (PI) using Vogel’s model, also determining other parameters such as permeability, net pay, viscosity, formation volume factor and drainage radius. To determine the Skin Factor (S) based on Darcy’s, then to calculate Skin damage (Sd). The work was done with four wells, two oil wells from X field which is an offshore carbonate field were treated with matrix acidizing, the wells are well (1) and well (2). The others are oil wells from Y field which is an on-land sandstone field that were treated with acid wash, the wells are well (3) and well (4). As a result of analyzing the data, the conclusion come to be that the Skin factor decreased for well well (1) by 76.9 %, for well well (2) by 57.6%, for well well (3) by 10.3%, and for well well (4) a slight decrease of 3.2% was observed .