Extension The Validity Technology, Increasing Injection In Polymer Flooding Injection Well Plugging

Polymer flood has been one of the most promising tertiary oil production methods, which possesses characters of enhancing recovery efficiency and economic benefit to a great extent Daqing oilfield has entered into industrialized popularization application stage and achieved better effects of increasing oil and decreasing water. But along with the increasing injection volume of polymer, under injection situations such as intermittent injection or short of injection allocation for it's high injection pressure are highlighting increasingly, which affect polymer flood effects seriously. The under injection of polymer is not always created by plugging but also by such other factors as the higher polymer injection project and geology factors etc. Aiming at these problems, conventional hydraulic fracture and chemical plug removal have been applied in field, but it can't solve the short valid period radically although some effects have been made. Lacking systematic analysis that causes under injection of polymer injection wells is the main reason. The investigations of plugging reason plugging extent, plugging rule don't make progress thoroughly even if the reasons of under injection has been realized more; Lacking a suit of effective plugging diagnosis and treatment optimizing technology result in a blind measure. It is imperative that short valid period problem after low permeability reservoir was reconstructed must be solved. So in this article, the reason of under injection was analyzed, combined with the former static and dynamic data, connection situation, physical properties of reservoir and other parameters of treated wells, then applied nerve net to develop plug judgment and treatment optimizing technology. Aiming at under injection resulted from plugging, plugging reason > plugging extent > plugging rule were investigated through component analysis of plugging agents in laboratory, the main compound plug removal ingredient % reservoir protection ingredient and operating techniques of single chemical plug removal and chemical plug removal combined with reservoir protection was investigated. Under injection caused by bad physical properties of reservoir has accounted for big proportion in Daqing oilfield, this type of polymer injection wells using chemical plug removal treatment has short valid period and bad effect, aiming at problem of conventional hydraulic fracture, the reason of short valid period of fracture treatment for polymer injection wells was investigated through solid dynamics analysis and physical model simulative experiment in laboratory, a new type of integral fracture sand inhibitor technology using resin sand as san consolidation agent was investigated. It achieved better effects on effects on laboratory experiment and field application, the oxidation degradation rate of polymer floccules of drainage matter from bottom well can reach over 99.50% by using chemical compound plug removal agent ingredient, meanwhile, it can dissolve nearly all mechanical impurity and other plugging. After compound plug removal, core permeability restoring rate can be 132.8% averagely; For formation protector, total damage rate can be decreased by 19.6%, and core permeability can be improved 132-165% in condition of injecting 60PV polymer after treated by protector contrasting to blank. This technology have been applied for 17 wells, the average valid period is up to 6 month, longest 12month, effective rate 94%, and pressure decreased by 1.50MPa in early stage after treatment. For fracture sand inhibitor technology of polymer flood injection wells, the permeability and diversion capacity of resin sand after solidification was evaluated, contract to silica sand, when close pressure is under 20Mpa, the permeability and diversioncapacity is lower about 18% than silica sand ,while over 30Mpa, it is higher than silica sand ; the crude oik formation water and acid can't affect resin coating sand, but alkali can affect resin sand at normal temperature greatly, resin sand has good compatibility with polymer solution, the viscos...