In a certain area of Karamay Oilfield，numerous production wells suffer from rapid water cut rise and high water cut after fracturing treatments. To solve this problem，the proppant grafted with the hydrophobic association relative permeability regulator，RPM-SiO₂，was developed by grafting the hydrophobic association relative permeability regulator onto the quartz sand surface，with the help of silane coupling agents KH570. The grafting of relative permeability regulators onto the proppant surface was confirmed successful by infrared spectroscopy and electron scanning microscopy （SEM）. Under the reservoir conditions of the study area of Karamay Oilfield，the differences of conventional performance （wettability，density，acid solubility and compressive strength），fracture conductivity，and water control ability between RPM-SiO₂ and blank quartz sand proppants were investigated. The results show that the comprehensive performances of RPM-SiO₂ and quartz sands are basically consistent，both meeting the requirements of the industrial standard. The resultant oil phase fracture conductivities are consistent，but the water phase fracture conductivity of RPM-SiO₂ is 25% lower than that of quartz sands. Compared with quartz sands，RPM-SiO₂ presents a decrease of 83.41% in the water phase permeability，17.49% in the oil phse permeability，and 18.65% in the water cut of produced liquid. RPM-SiO₂ has high water control capability and long-term effectiveness.

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.

The post-frac flowback and production of the alkali-salt layers of Fengcheng Formation in Mahu Sag suffer from wellbore salt deposition，but the salt deposition law remains unclear. Therefore，through static and dynamic salt precipitation evaluation experiments，the reservoir conditions affecting the salt precipitation rate and the impacts of flow rate and gas production on wellbore salt deposition in the production process are investigated to clarify the wellbore salt deposition law. The results show that the three typical salts，with their solubility from most to least sensitive to temperature，are sodium carbonate，sodium bicarbonate and sodium chloride. Moreover，the boundary conditions （total salinity and ion composition） and salt crystal types of salt crystal precipitation are defined for composite salt solutions with different compositions. Under the same salinity，the precipitation degrees of composite salts with different compositions are between those of the individual salt，and the priority orders of salt precipitation are sodium bicarbonate，sodium carbonate and sodium chloride，which is consistent with the change of solubility of various salts with temperature. With the increasing flow rate and gas production，the salt deposition first grows and then declines. The salt deposition peaks in the case of the daily liquid production of 40 m³/L and the gas-liquid ratio of 200 m³/L.The study on the salt deposition law in alkali-salt wells helps to set reasonable drainage parameters，delay the salt deposition during flowback，ensure the smooth completion of formation testing after fracturing，and provide a theoretical basis for on-site salt prevention measures in the later production from Fengcheng Formation alkali-salt layers.

In this era of Internet and Big Data，the application of machine learning，which is the core of artificial intelligence，in drilling engineering represents a general future development orientation. Drilling engineering is an essential part of hydrocarbon exploration and development technology. Machine learning-based drilling parameter optimization and accident prediction and warning are vital for economy，safety，efficiency，and environmental-friendliness. Given that it is hard to effectively guide the drilling operation for deep and ultra-deep wells using the previous experience and data，this research summarizes the present algorithms used in machine learning first，and gives a preliminary analysis for the benefits of machine learning in drilling engineering consequently. A review of global studies on applications of machine learning in drilling engineering is presented and the challenges are identified. Some suggestions are proposed，in an attempt to promote contributions of machine learning in the development of drilling engineering of China.

A study on a highly-efficient anti-swelling and salt-resistant slickwater fracturing fluid system was conducted based on the wastewater from fluid preparation in an oilfield. This study was designed to solve the blockage problem of induced fractures and matrix pores and throats due to the hydration expansion and even rock skeleton collapse after fracturing fluid system contacts a readily loose reservoir with high clay content,strong water sensitivity,and weak cementation. The experimental results show that a highly efficient anti-swelling and salt-resistant slick water fracturing fluid system prepared from 0.05% KY-2 （salt-resistant drag reducer ）,0.4% FP-3 （organic amine compound anti-swelling agent）,0.1% ZP-2 （cleanup additive）,and the said waste water with a TDS of 15 548.96 mg/L has an anti-swelling rate （96.2%） equivalent to 4% KCl,which means a satisfactory anti-swelling performance. After washing with tap-water for 10 times,the anti-swelling rate is still as high as 89.87%,which means a satisfactory long-acting anti-swelling performance. Besides,with a drag reduction rate of 78.45%,this system has a satisfactory drag reduction performance. Field test results have validated that the new system can effectively alleviate the problems of high KCl consumption,high cost,and inability to use mixing-free process in strong water-sensitive reservoirs,as well as the decrease in drag reduction rate due to high TDS.

By establishing a long sand-packing model with satisfactory reproducibility for porosity, permeability parameters and sand-packing stability, the flow characteristics and oil displacement effect of associating polymers with different hydrophobe contents at a similar shear viscosity were investigated under conditions with different permeabilities and max-to-min permeability ratios. The results show that, in the permeability range of 0.55~6.93 μm ², the polymer without hydrophobes (DM-0) always exhibits an identical "equal resistance" pattern; while the associating polymers DM-1~DM-3 respectively demonstrates a flow pattern of "equal resistance" and "increasing resistance" before and after a certain critical permeability, and the critical permeability notably increases with increasing hydrophobe content. Moreover, the combination pattern of "increasing resistance + increasing resistance" can achieve the best oil displacement effect, and the higher hydrophobe content the greater max-to-min permeability ratio. The synergetic oil displacement of associating polymers with different flow patterns can provide important technical reference for heterogeneous reservoirs to enhance recovery factor significantly.