New Insights on Acid Stimulation of Sour Gas Wells With Flowback To Facilities Without Production Test Equipment

摘要

This paper describes some of the operational aspects, planning practices and improvements in both coil tubing and bullhead acid stimulation campaigns carried out to increase the performance of gas-producing wells in a mature sour-gas asset. The objective of the campaign was to reduce operational costs by flowing the wells back directly into the production facilities after the treatment, without the use of temporary production test equipment. This strategy would be considered successful, if it could be proven to be technically well-executed, and compliant with HSSE directives. By engaging in a multi-disciplinary approach, critical aspects of this campaign were identified at an early stage, including selection of fit-for-purpose stimulation formulation. Furthermore a novel corrosion inhibitor capable of withstanding unspent acid in a sour system was deployed in the facilities for integrity and protection. Key performance indicators for the campaign were set, including target pH values for flowback samples. Monitoring of H2S concentration of the produced gas was carried out, and control with the use of a H2S scavenger injected in well flowlines allowed for export gas specifications to be maintained. Overall the campaign generated significant productivity improvements. This cost-effective acid stimulation is therefore a valuable tool for well reservoir and facilities management in the asset.