This study aims to develop an efficient and environmentally friendly approach for the resource recovery and harmless treatment of waste oil-based drilling mud (WOM). A comprehensive treatment process was implemented, including chemical demulsification and mechanical dehydration of WOM, advanced oxidation and coagulation-flocculation treatment of intermediate water (IW), and cement-based solidification of dehydrated mud (DM). The results demonstrate that the dehydration process achieved excellent oil recovery (95.62%) and volume reduction (93.20%), with residual oil and water contents of 0.40% and 4.33% in DM, respectively. The IW treatment (pH adjustment to 6, 5000 mg/L NaClO oxidation for 25 min, followed by pH 9 adjustment and sequential addition of 120 mg/L PAC and 8 mg/L APAM) produced clean water (CW) with 98.6% transmittance (TR), suitable for fracturing fluid preparation. Furthermore, DM solidified with fly ash: cement: quicklime (10%:30%:20%) exhibited high compressive strength (16.22 MPa) and leachate meeting national discharge standards. This integrated approach successfully transforms hazardous WOM into reusable resources while ensuring environmental compliance, providing a practical solution for sustainable drilling waste management.

Pore-environment adjustment occurs during continuous flow in fine-grained sandstone, yet NMR, CT and SEM responses are not one-to-one. Montmorillonite-bearing sandstone was studied: 12 cores matched by porosity and gas permeability from 60 samples were divided into four flow levels (0.1, 0.5, 1.0 and 1.5 mL/min), with three parallel cores in each group. White oil (4.5 mPa·s) was flowed at 40 °C and 5 MPa. NMR and CT were measured at 2, 4, 6 and 8 h after saturation, and SEM was performed before and after flow. Group means show short relaxation rising and long relaxation falling continuously, with changes at the same time point generally increasing with flow rate. At 8 h, the relative change rate of short relaxation increased from 6.31% to 70.86%, long-relaxation attenua-tion from 6.26% to 62.91%, the CT small-pore fraction increased by 0.89–17.46 percentage points, and the large-pore fraction decreased by 1.81–22.32 percentage points. In high-er-flow groups, relaxation peaked at 4 h and CT pore proportion at 6 h. Even after nor-malizing for cumulative fluid volume, higher-flow groups responded more strongly. These trends support particle release, redistribution and local retention, and the parallel design strengthens the flow-rate–pore-response correlation.