Green Growth and Sustainable Development on the Way: A Case Study from Fracturing Campaign in South Sulige Gas Field

Abstract The South Sulige gas field is located in the middle of the Mu Us Desert in Inner Mongolia, with an arid climate, sparse vegetation, scarce water resources, and a fragile ecological environment. As the main operator in this field, South Sulige Operating Company (SSOC), a joint venture company between CNPC and TotalEnergies, aims to accelerate its transformation to green growth and sustainable development by reducing water consumption and carbon emissions in the fracturing campaign. This paper describes a novel flowback-water treatment process, which can quickly treat the post-fracturing flowback water onsite with satisfactory water quality, required treating rate, and minimized cost. The treated flowback water will be used for mixing guar gel and fracturing in offset wells of the same pad. In addition, a specially designed gas capture and recovery unit is installed on the wellsite. Natural gas could be directly discharged into the downstream production network during the well cleanup period. Furthermore, an attempt was also made to substitute a traditional diesel fracturing pump with an electric-drive fracturing pump using the state grid. Reuse of flowback water can reduce water consumption and waste disposal, which is critical for deserts and grasslands. Unlike the simple practice of treating flowback water to mix slickwater for pump-down in the adjacent blocks, remixing guar gel is required to place a high concentration of proppant and thus keep high post-fracturing production performance. The laboratory analysis result shows that the key ions in the treated flowback water meet the requirement for mixing gel. The core damage test also shows an equivalent level between treated flowback water and clean water. The maximum daily treating rate for one treating package was 700 m3/day and clean fluid yield rate was 80%. The yearly flowback water reuse ratio reached 40% and roughly saved 14% of the entire water consumption. On the other hand, a large volume of natural gas was captured after the special recovery units were utilized for a total recovery time of 5073.8 hours in 2023. Also, electric-drive fracturing pumps were used in 58 wells, which was 47.5% of the yearly work scope. These efforts resulted in approximately 76,900 t carbon emission reduction for the last fracturing campaign. In the development of a tight gas field, to produce industrial gas flow from target wells, hydraulic fracturing is usually required. With more attention paid to environmental protection worldwide, how to balance project profitability with resource consumption and carbon emissions has become a critical consideration in the hydraulic fracturing domain. The practices described in this paper may be well adapted to other blocks with similar development features.