Alkali-surfactant-polymer combination flooding (ASP flooding) is one of the main chemical EOR techniques for the significant increase of crude oil recovery in PetroChina. In this paper, the progress in field tests of ASP flooding, effects analysis and related problems in application are introduced and discussed. The development trend of ASP flooding is suggested. Field tests of ASP flooding in PetroChina have been performed since 1994, including six pilot tests in both sandstone and conglomerate reservoirs and three industrial tests, and the incremental oil recoveries of such tests were more than 19–20%. It is found that three factors are responsible for successful ASP flooding field tests : (1) Good performance of oil displacement agents. (2) Good profile control and oil displacement ability. (3) Reasonable well pattern and well spacing. Side effects encountered in field tests are as follows: (1) scaling and corrosion damaged the lifting system and shorten the average pump-checking cycle accordingly. (2) Strong emulsification resulted in many liquid treatment problems such as the excess of solid particle content over the standard of water circulation and high cost of water treatment. (3)The liquid production decreased greatly. The development trends in chemical combination flooding technique are proposed based on results of ASP flooding field tests. The strong alkali ASP flooding should be replaced by weak alkali ASP flooding or even alkali-free SP combination flooding. The application reservoir will cover from sandstone to conglomerate and carbonate, from low salinity and low temperature reservoirs to high salinity and high temperature ones, etc. The corresponding key techniques such as development of new chemical agents and advanced produced liquid treatment system should be considered in future tests and application of chemical combination flooding.

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The last decade has witnessed unmanned aerial vehicles (UAVs) emerging as a powerful platform for various industrial and civilian applications. However, refrained by limited battery capacities, the hovering time of UAVs is still limited, impeding them from achieving remote tasks, such as wide area inspection. To deal with such long-range applications, a common sense solution is to employ vehicles to transport, launch, and recycle UAVs. Efficient routing and scheduling for UAVs and vehicles can greatly reduce time consumption and financial expenses incurred in long-range inspection. Nevertheless, prior works in vehicle-assisted UAV inspection considered only one UAV, and was incapable of concurrently serving multiple targets distributed in an area. Leveraging multiple UAVs to serve multiple targets in parallel can significantly enhance efficiency and expand service areas. Therefore, in this paper, we propose a novel hybrid genetic algorithm (HGA), which supports the cooperation of one vehicle and multiple drones for wide area inspection applications. HGA allows multiple UAVs to launch and recycle in different locations, minimizing time wastage for both the vehicle and UAVs. Performance evaluation is presented to demonstrate the effectiveness and efficiency of our algorithm when compared with existing solutions.INDEX TERMS Unmanned aerial vehicle, inspection, routing, scheduling.