Research and Experiments of a Clean Fracturing Fluid System with CO2 Foam Gemini Surfactant

Current prevailing fracturing fluid systems exhibit problems in the fracturing of unconventional oil and gas reservoirs such as poor formation compatibility,difficult gel breaking and flowback as well as secondary damage to formations,so they cannot meet the requirements of fracturing in unconventional oil and gas wells.To overcome these problems,a new type of gemini cationic surfactant WG-2 was synthesized in combination of the characteristics of clean fracturing fluid and foam fracturing fluid.On this basis,a clean fracturing fluid system with CO2 foam gemini surfactant was developed and its comprehensive performance was evaluated in the laboratory.The evaluation results demonstrated that the fracturing fluid system has strong foam stability,good temperature and shear resistance,viscoelastic properties,sand carrying capacity,gel breaking performance and low damage characteristics.The clean fracturing fluid with CO2 foam gemini surfactant was used in Well X-3 for field tests.The fracturing operation went well,and the daily oil production after fracturing was twice of that from adjacent Well X-4,which had been fractured with the fracturing fluid system of hydroxy propyl guar gum.The results of laboratory and field tests showed that this fracturing fluid system could meet the fracturing operation requirements for unconventional oil and gas reservoirs and also possesses good popularization and application prospects.