To improve the utilization rate of phosphate tailings (PTs) and widen the sources of subgrade filler, the PTs is employed to modify clay, forming a PTs modified clay, applied in the subgrade. Accordingly, the environmental friendliness of PTs was investigated. Subsequently, an optimal proportion was determined through compaction and California Bearing Ratio (CBR) experiments. Afterward, the stability of mixture with the optimal proportion was further evaluated through the water stability and dry-wet stability experiments. Finally, via the gradation and microstructure experiments, the strength mechanism of PTs modified clay was analyzed. The results show that the PTs were classified in the non-hazardous solid wastes, belonging to Class A building materials. With the increase of PTs content and the decrease of clay content, the optimum water content and the swelling degree gradually decrease, while the maximum dry density and CBR first increase and then decrease, reaching their peak value at 50% PTs content, which is the optimal proportion. The resilient modulus of PTs modified clay at the optimal proportion reaches 110.2 MPa. The water stability coefficient becomes stable after soaking for 4 days, while the dry-wet stability coefficient decreases with the increase of cycles and tends to be stable after 8 cycles. Under the long-term action, the dry-wet change has a greater adverse impact than continuous soaking. The analysis demonstrates that the better strength mainly comes from the skeleton role of PTs and the cementation of clay. The systematic laboratory test results and economic analysis collectively provide data evidence for the advantages of PTs modified clay as a subgrade filler.

Drilling-waste management is of great importance in the oil and gas industry due to the substantial volume of multi-component waste generated during the production process. Improper waste handling can pose serious environmental risks, including soil and water contamination and the release of harmful chemicals. Failure to properly manage waste can result in large fines and legal consequences, as well as damage to corporate reputation. Proper drilling-waste management is essential to mitigate these risks and ensure the sustainable and responsible operation of oil and gas projects. It involves the use of advanced technologies and best practices to treat and utilize drilling waste in an environmentally safe and cost-effective manner. This article describes a feasibility study of four drilling-waste management options in the context of the Khanty-Mansi Autonomous Okrug of Russia. For ten years of the project life, the NPV under the base scenario is equal to RUB -3374.3 million, under the first scenario is equal to RUB -1466.7 million, under the second scenario is equal to RUB -1666.8 million and under the third scenario is equal to RUB -792.4 million. When considering projects, regardless of oil production, the project under the third scenario pays off in 7.8 years and the NPV is RUB 7.04 million. The MCD and MCV parameters were calculated to be 106 km and 2290 tons, respectively. Furthermore, the study estimates the ecological damage prevented and the environmental effect of each option. Quantitative risk assessments, conducted through sensitivity analysis, reveal that the fourth option, involving the conversion of drilling waste into construction materials, emerges as the most economically feasible. The study also evaluates the interaction between business and government and analyzes the current situation in the sphere of drilling-waste management, concluding with concise recommendations for both companies and official bodies.