Study on environment-friendly disposal and utilization of oil-based drilling cuttings solidified body of shale gas

Large amounts of oil-based drilling cuttings (ODC) will be generated from shale gas exploitation, and the traditional way to deal with it is to solidify the drilling cuttings. There are potential environmental risks associated with this endeavor. So, the safe and environment-friendly disposal and utilization of oil-based drilling cuttings solidified body(ODCSB) were studied. The chemical composition, mineral composition, thermal analysis, radionuclide and other basic physical characteristics of the ODCSB were analyzed by modern test methods. Also, the kiln entry characteristics of the ODCSB were deeply studied, and the raw meal calcination formula of the ODCSB was reasonably designed. The chemical composition, mineral composition and microstructure of the cement clinker obtained are almost the same as those produced by a large cement plant, and the tail gas in the calcination process also meets the requirements of the Chinese standard(GB 30485). In addition, the clinker was used as a raw material to prepare ordinary Portland cement. The results show that the compressive strength, setting time, water requirement of standard consistency, mineral composition and microstructure of ODCSB cement are basically the same as those of cement produced in a large cement plant. It can be seen that the cement prepared by the right amount of ODCSB can meet the relevant requirements of Chinese standard(GB 175). At the same time, the leaching toxicity of heavy metals in the cement was also tested. Results show Cd was not detected, Cr was 50.3 mg/kg, Pb was 44.6 mg/kg, As was 12.8 mg/kg, Ni was 9.1 mg/kg, Hg was 0.11 mg/kg, are lower than the relevant limit requirements in the Chinese standard(GB 30760). In conclusion, the quality and heavy metal content of common Portland cement produced by ODCSB meet the requirements of corresponding standards, and the micro properties of ODCSB cement are also close to the commercially available cement. So, it is an effective way of safe and environment-friendly disposal and utilization of ODCSB.

Automated summary

This study analyzed the chemical and physical characteristics of oil-based drilling cuttings solidified body (ODCSB) and successfully developed a low-cost and high-quality cement preparation method. The results show that the cement produced from ODCSB meets the relevant standards and exhibits micro properties similar to commercially available cement.