A classified-targeted treatment approach for resource recovery of water-based drilling solid waste in natural gas exploitation

Drilling solid waste from oil and gas operations contains hazardous components that pose long-term risks to soil and groundwater. Existing studies predominantly treat heterogeneous waste streams as uniform materials, neglecting well-section-specific contamination profiles and the potential for differentiated treatment protocols. To date, no systematic framework has been proposed that integrates classification-based waste segregation, differentiated treatment protocols calibrated to contaminant profiles, and verified resource recovery pathways within a unified treatment architecture. This study proposes a classified-targeted treatment approach that integrates waste classification at the source, differentiated treatment protocols, and validated resource utilization pathways. Through characteristic-based classification, upper-section waste was rendered compliant with pollutant discharge standards through physicochemical pretreatment, while lower-section waste was effectively detoxified via high-temperature incineration. All evaluated parameters, including liquid limit, plastic limit, California Bearing Ratio, organic content, and loss on ignition, for both waste fractions fully satisfied the technical requirements for subgrade fill materials stipulated in China's Technical Specifications for Construction of Highway Subgrades and Specifications for Design of Highway Subgrades. A comparative cost analysis based on non-fired brick production demonstrates that the proposed approach achieves a 48% reduction in treatment costs relative to conventional mixed treatment methods. These findings provide scientific and technical basis for the resource utilization of drilling solid waste, supporting sustainable development in the energy sector within the dual carbon policy framework.