Vaca Muerta Corrosiveness and Its Impact in Production Strategy

The complexity of the problem and the severity of corrosion found at certain fields of shale gas in Vaca Muerta made necessary to develop a program that included predictive analysis through semi-empirical corrosion-erosion models, comparison of materials through the installation of coupons in downhole wells and, finally, the execution of several pilots in the field under real operating conditions. On top of this, an exhaustive monitoring of the physical-chemical conditions of the fluids and the performance of the analyzed materials was executed. The corrosion problem associated with the development of Vaca Muerta is extremely complex. Aggressive agents such as CO2 were observed in a wide range of quantities, accompanied by a high concentration of chlorides in the flow-back water together with high initial flows and the presence of a high concentration of sand of fracture (proppant) in the early stage of the well. The combination of these agents presupposes a risky scenario for some tubular materials. Therefore, to limit the probability of failure and ensure the integrity of the installations during the production life, a coupon evaluation program was carried out in the field with alloys containing 3% and 13% Cr, accompanied by predictive analysis, loss of thickness in pipe through different models known in the industry. Finally, a pilot program has been executed at the field, monitoring the pipes with successive multi-fingers calipers to determine the impact of corrosion on the materials. The conclusion of this entire process made it possible to establish a production strategy that minimizes the risk of failure due to corrosion and contributes to the integrity of the downhole installations during their service life, minimizing interventions and ensuring the operational continuity of the well. All this process is going to be presented at this work, detailing the engineering process prior to propose an alternative to mitigate the problem from the joint vision of an operator in the region and a tubular manufacturer.