Study On Multifunction Compound Profile Modification Technology For Ultra-low Permeability Fracture Reservoir

After the oil field inject into water and start to exploitate, because of ultra-low permeability reservoir existing natural fracture, the water in oil field make a sharp increase, production decrease rapidly, reservoir recovery is low. meanwhile, through studying the literatures both at home and abroad, we think out that at present there is not a particularyly suitable profile modification technology for ultra-low permeability fractured reservoir. This type of reservoir's profile modification technology has been a generally difficult problem to resolve,the former blocking technology only focused on micro-fracture closure, while neglected the transfer agent's role in edge-water encroachment and washing oil, resulting in bad effect in Profiling and washing oil, This greatly affected the extent of crude oil recovery. Thus. In response to the reservoir characteristics, this paper present the multi-functional compound profile modification technology, which is a new technology combined profile technology with chemical edge-water encroachment technology to enhance oil recovery. this study has an important practical significance for profile oil field to further enhance oil recovery as well as for non-profile oil field to enhance oil recovery more effectively. In this paper, we firstly take Yanchang's ultra-low permeability oil fields for example to study micro-fracture characteristics of fractured reservoir. through electron microscopy scanning, we obtain that micro-fracture of ultra-low permeability reservoir are non-ordinary development. the opening extent of micro-fracture are between some of microns and tens of microns. while the pore throat radius of the matrix is basically at sub-micron level. In response to the specific reservoir characteristics, In this paper, we select nanospheres profile control agent and the SW-b surfactant flooding as a compound profile modification system, and evaluate its reservoir adaptability. The results show that: Surfactants are with good anti-high salinity and changes in rock wettability, also has very good performance of washing oil. Nanospheres are with good function of anti-temperature and salt, also has very good expansion, migration, and blocking performance. interaction studies between nanospheres and surfactants show that Nanoparticles and surfactants have good compatibility,. secondly, we went through physical simulation experiment to research the compound profile modification technological parameter, reached the reasonablen concentration of profile modification agent and the best phase piston. and discuss the repeated round profile modification, The article also study the feasibility and mechanism of compound profile modification to enhance oil recovery the result show that nanospheres after profile treatment using surfactant can furtherly enhance oil recovery to a certain extent, illuminate that compound profile modification technology of fractured reservoir is feasible. the causes of compound profile modification to enhance oil recovery profile and chemical oil displacement agent perse play an important role in improving edge-water encroachment efficiency and affecting volume, besides , have a good synergy, namely nanoparticles play role in deep flow changing direction, make that the follow surfactant and water can effectively enter the not enough development stratum, such as ultra-low permeability. chemical oil displacement agent give full play to enhanc oil recovery in these areas where residual oil are concentration. Finally, we on-site apply nanospheres-surfactant compound profile modification technology to Yanchang ultra-low permeability fractured reservoir. The results show that the technology can greatly enhance the water pressure, change reservoir's water section, significantly improve oil recovery. Therefore ,the technology in ultra-low permeability fractured reservoir compound profile modification is with a very broad application prospects.