When planning a stimulation treatment on carbonate formations, often the main dilemma is to choose between proppant fracturing or acid fracturing: the criteria that leads to one choice or the other depends on several aspects which are mainly related to the characteristics of the formation to be stimulated.
This paper will describe a successful experience of an acid fracturing campaign that was performed on a carbonate reservoir in the offshore Congo; two multi stage treatments were executed with the support of a stimulation vessel using specially formulated fluids that were a key to success of the stimulation job.
Completion strategy consisted of open hole, ball activated multi stage frac sleeves that allowed to achieve stimulation effectiveness and efficient target reservoir coverage. Focus will also be given on how the selection of the technology to be used was carried out: acid fracturing was preferred to proppant fracturing based on the formation characterization and because of the proximity to water contact. This decision was also based on post job analysis of previous treatments performed in the past on the same formation which included both acid and proppant fracturing. Post job performance of the newly treated wells is also presented in this paper.
