Acid's Behavior and Performance on the Matrix with Time - Hassi R'mel Field, Algeria

Sandstone matrix stimulation has been the subject of extensive investigations for over 40 years and extensive experimental work has been conducted to investigate the reactions of various mud acid systems with damaging and formation materials[1-2-3]. Theoretical analysis and modelling of the stimulation process have also been studied by some investigators[4-5-6]. Another experiment of acidizing was realised in Hassi-R'Mel field with 3 types of acid. This field is a gas condensate reservoir with a superposition of three layers having very good petrophysic characteristics. A decrease in production of the wells was observed in the various zones. Build up tests realised on those wells showed significant skin, which is due primarily to the excessive invasion of the mud used during drilling and Work Overs. For that, a stimulation by acidizing was decided to optimise and to improve the potential of these wells which is less than that hoped within sight of their petrophysic characteristics. In order to study the effects of stimulation, PLT’s were realised before and after the acidizing. Before stimulation, studies were undertaken to see and analyze each acid's behavior on the matrix and to draw the conclusions on the capacities and disadvantages of each one of them on the reservoir. The analyses carried out before, during the acidizing and several years after us made it possible to make a technical and economic study which will enable to see and to understand acid's behavior with time and its impacts on the reservoir , on the wells's equipment and investment costs. The purpose of this presentation is to show: -various methods of acidizing used and the concentrations used. -acid's behavior and performance on matrix with time -the advantages and disadvantages from this stimulation campaign. -the ratio of the profit on the capital costs after the operation of acidizing