A Novel Approach to Acidizing of Carbonates: Case History From the Gulf of Suez in Egypt

摘要

This case history develops through the drilling of a relativelyrnunderexplored and less promising limestone formation in thernGulf of Suez area of Egypt. The target formation, known asrnThebes of Eocene Age, was “faulted” and the two separatedrnpay sections presented different rock compositional scenarios.rnEven though the geological description broadly classifiedrnthese zones as carbonates, the stimulation treatments designedrnfor the two zones were totally different. The process that wasrnundertaken in determining the best solution was based on thernintroduction of some novel analytical techniques and a comprehensivernapproach to acidizing-treatment design.rnThis paper details some of the new approaches that werernused, including a composite log developed for carbonatestimulationrndesign. The emphasis on reservoir characterizationrnin terms of its petrophysical properties and productionrncapability is paramount in carbonates because of the extremernreservoir heterogeneity and a general noncorrelation betweenrnrock porosity and permeability. Furthermore, a new matrixrnacidizing simulator was run with input data from the compositernlog for modeling fluid distribution and skin evolution from therntreatment. On the basis of these simulation runs, a couple ofrnpre-emptive measures were taken to improve the treatmentfluidrndistribution profile.rnBottomhole pressure gauges in conjunction with real-timernmonitoring of skin evolution during the treatment were analyzedrnfor determining the effectiveness and applicability ofrnfoamed treatments, in-situ crosslinked acid systems, and maximumrnpressure differential and injection rate (MAPDIR) techniques.The post-stimulation production results and pressurebuilduprnsurveys confirmed the success and effectiveness of thernstimulation treatments.