Advances in Carbonate Stimulation Methodology – From Wormholes to Long-Term Productivity

Effective acid stimulation can be critical to achieving the desired long-term production rates from targeted reservoir layers. ExxonMobil has developed an integrated, multi-disciplinary methodology for carbonate matrix stimulation of long completion intervals.¹  The methodology is a continuous process which includes geological characterization, reservoir objectives, completion strategy, stimulation design with the necessary experimental testing, implementation, and evaluation. The methodology has recently been customized in collaboration with RasGas to achieve objectives for K1-K3²  and K1-K4³  completions in the North Field, the world’s largest, non-associated gas field.

Building upon this success, ExxonMobil continues to study the fundamentals of carbonate stimulation and its impact on long-term productivity to enhance the process and apply it to a wider range of reservoirs and well types. This paper presents preliminary results from three areas of ongoing research: (a) improved understanding of 3-D wormhole growth through large-scale experiments and visualization techniques, (b) integrated wormhole modeling and complex fluid flow during stimulation of long horizontal wells, and (c) enhanced post-stimulation evaluation method that integrates stimulation physics, well test analyses, and long-term reservoir performance predictions. Integration of these technological advancements with existing knowledge provides an enhanced methodology for the stimulation of carbonate reservoirs with an increased focus on long-term productivity.