Longdong Oil Block requires the full implementation of drilling fluid non-landing technology to promote the recycling of waste drilling fluid. In order to solve the problem that the performance of water-based drilling fluids prepared using on-site hydraulic filtrate waste cannot meet the standards and the influencing factors are not clear，the ethylene diamine tetraacetic acid（EDTA） titration，bacterial plate counting method and atomic absorption spectrometry （AAS） were used to investigate the key techniques to improve the reuse rate of hydraulic filtrate waste. The experiments show that the high content of calcium and magnesium ions，bacteria，and heavy metals are the main reasons for the poor performance of water-based drilling fluids prepared using hydraulic filtrate waste. Correspondingly，the modified coagulation and precipitation complexing agent II，polyether demulsifier JX，and flocculants ZY-I，ZY-II have been developed to perform the flocculation-precipitation-sterilization treatment together with the sterilizing agent. The resultant average removal rate of calcium and magnesium ions is 95.5%，the sterilization rates of saprophytic bacteria （TGB） and sulfate-reducing bacteria （SRB） are 96.54% and 100% respectively，and the heavy metal content is less than 2.31 μg/L. The laboratory tests of recycling of hydraulic filtrate waste and water-based drilling fluid preparation have been completed for 6 wells in Longdong Oil Block. Longdong Oil Block waste drilling fluid hydraulic filtrate recycling technology has been formed and applied in 5 wells of this block. The water-based drilling fluids prepared using the recycled hydraulic filtrate waste presents a performance in line with the drilling engineering design requirements，facilitating the smooth drilling process，effectively protecting the environment and saved water resources，demonstrating good prospects for application promotion.

Chemical flooding plays an important role in improving oilfield recovery. The micro-emulsion system has been widely studied and applied owing to its unique properties. In this experiment，the alcohols with carbon numbers less than five were selected as cosurfactants to optimize the performance of the micro-emulsion system. The dynamic oil displacement process，morphology and distribution of residual oil and displacement performance of micro-emulsion flooding were visualized using microfluidic technology. Firstly，the mass fractions of isopropanol and n-butanol in the cosurfactants were optimized，followed by the optimization of NaCl mass fractions. Ultimately，microscopic visual displacement experiments were conducted with the optimal micro-emulsion formulation. The results show that the optimal micro-emulsion formulation is as follows：an fixed oil-water ratio of 1∶1，5 wt% SDS，8 wt% n-butanol and 3 wt% NaCl as the optimum. The corresponding ultimate oil recovery is 98.8%，and the residual oil saturations are 0.15% and 1.05% in the high- and low- permeability zones，respectively. NaCl can change the polarity of water to reduce interfacial tension. The combination of n-butanol with surfactants and NaCl can greatly reduce interfacial tension and modify the wettability of the microfluidic chip，leading to promoted oil detachment and enhanced mobility of residual oil. Using microfluidic technology to study the in situ emulsification and dynamic displacement process of micro-emulsions provides effective theoretical guidance and technical support for efficient development of reservoir residual oil.