Research On The Multi-hydrogen Acid System For Reducing Pressure And Increasing Injection In Hainan 3 Block

Hainan3 block of Liaohe Offshore Oilfield is the key of water flooding block.Presently,oil producing capacity accounts for more than 80%of the company’s oil production.There are 34 injection wells,17 high pressure injection wells and 7 wells under injection.The reinjection sewage water quality in the block is not up to standard,coursing formation damage increasingly,water injection rate fallen sharply and injection pressure rising rapidly.The causes of injection wells blockage were analyzed through the research on plugging mechanism and sensitivity evaluation.The results show that a large number of inorganic scale,organic scale were formed in reservoir by oil,miscellaneous machine,bacteria in reinjection sewage water to plug formation and lower permeability.In view of the fault block,acidolysis hydrogen blocking system was developed and optimized to promote the performance.Based on core analysis and sensitivity experiments,organic matter is dissolved by the system with organic solvent and additive to restore formation water wettability,reduce the interfacial tension between oil and water and eliminate the filtrate that may bring damage to reservoir.In addition,the system is effective in dissolution of plugging particles of solid particles,and that eliminates the damage of solid phased particles to formation.The system has been used for 14 times in the field,dropping 12 MPa for average with validity period more than one year.