1. Overview of Polymer Injection
In September 2008, polymer injection experiment started at T oil field (about 65% water cut) with 3 injectors and 10 producers. Most wells had response in early stage. The overall fluid and oil production in pilot area increased. In mid-to-late stage, multiple wells had a sharp rise in polymer concentration and glide in oil production. The results of pilot test differ from our prediction. The water cut in pilot area almost reached 90% until Sep. 2014.
2.Analyses of Current Problems
As the Characteristics of reservoir and fluid, following take placed：
ⅰ.Reservoir has strong heterogeneity. Polymers would tongue along high-permeability zone if general polymer injection applied.
ⅱ.In early stage, water saturation is low and water-oil mobility ratio is high. polymers finger along high water cut zone.
ⅲ.Fixed dominant channel would form on formation and ineffective circulation gets enhanced after long-time polymer injection.
As a consequence, something happened：
ⅰ.Polymer injection directivity up
ⅱ. Produced fluid water cut up
ⅲ.Polymer injection sweep efficiency down
ⅳ.Polymer flooding efficiency down
In later stage, reserves produced degree comes to be low with low polymer flooding efficiency. 3. Solutions to the Problems
3.1 Core Ideas: Firstly, Plug big channels and high permeability zones and bottom water. Secondly, adjust production profile and polymer injection profile, as the same time lower oil/water interfacial tension and water-oil mobility ratio.
3.2 Count measures:
3.2.1 When polymer produced without oil or oil came out with polymer, Plug water at deep ground of oil well with applying profile modification, furthermore separating layer polymer injection at deep ground of water well.
3.2.2 When few polymer produced without oil or oil produced before few polymer, or oil produced without polymer, plug water coning in oil well, with optimizing operating parameters of oil well and Inject viscosity reducer slug into water well.
3.2.3 When only oil produced before polymer occurred, execute selective water shutoff in oil well and apply selective distribution separate layer polymer injection in water well.
3.3 Work plan:
3.3.1 Polymer injector: Apply separate injection where interlayer development, and squeeze high-efficiency selective water shutoff agent.
3.3.2 Reservoir: Squeeze high-efficiency water shutoff agent slug and high-efficiency surfactant slug before polymer plug in used.
3.3.3 Oil well: Squeeze water shutoff agent and optimize the work parameters.
To know the exact project amount, comprehensive site analysis is needed!
3.4 Featured Product/Technology:
3.4.1 Intelligent Layered String
ⅰ. Distribute water steplessly and precisely.
ⅱ. Set parameters on the surface then underground layers regulate water input automatically;
ⅲ. Achieve arbitrary multiple separated injections if interlayer permits;
ⅳ. Temperature tolerance can reach 150℃. Injection pressure difference between heat-resistant coatings is 10MPa.
3.4.2 High-Efficiency Compound Plugging Agent
ⅰ. Use both organic and inorganic chemicals. Apply particles of different sizes and different slugs.
ⅱ. Match the optimum plugging place, plugging method and usage of slug to the circumstances.
3.4.3 High-Efficiency Surfactant
ⅰ. High salt resistance.
ⅱ. Low critical micellar concentration.
ⅲ. High activity. Good for the formation of O/W emulsion.
ⅳ. Work best under 15-80% water cut. 4. Further Work
4.1 Fine reservoir description of polymer injection area
ⅰ.Research on reservoir heterogeneity
ⅱ.Analysis on reservoir sensitivity
ⅲ.Analysis on heavy oil viscosity-temperature characteristics
ⅳ.3D geological model
ⅴ.Research on residual oil distribution characteristics
ⅵ.Research on reservoir numerical simulation
4.2 Research on improving polymer injection
ⅰ.Research on policy limit
ⅱ.Research on technical strategies
ⅲ.Designing and optimization
ⅳ.Ground equipment matching and construction technique design
4.3 Project economic evaluation
4.4 Project risk assessment
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