Numerical well testing interpretation model and applications in crossflow double-layer reservoirs by polymer flooding

Area of Science:

• Petroleum Engineering
• Reservoir Characterization
• Enhanced Oil Recovery

Background:

• Accurate formation evaluation is crucial for optimizing oil production, especially in complex reservoir systems.
• Polymer flooding is a widely used enhanced oil recovery (EOR) technique, but it can induce formation damage.
• Interpreting well test data in crossflow double-layer reservoirs presents unique challenges due to complex fluid flow dynamics.

Purpose of the Study:

• To develop and validate a numerical well testing interpretation model for crossflow double-layer reservoirs undergoing polymer flooding.
• To analyze the impact of various parameters, including rheology, inaccessible pore volume (IPV), and permeability reduction, on well test responses.
• To assess the model's capability in determining formation parameters and evaluating polymer-induced formation damage.

Main Methods:

• Establishment of a well testing model incorporating rheology, shear, diffusion, convection, IPV, permeability reduction, wellbore storage, and skin factors.
• Development of type curves based on the numerical model and analysis of parameter sensitivity.
• Validation of the model using field test data from polymer flooding operations in crossflow double-layer reservoirs.

Main Results:

• The developed type curves exhibit five distinct flow segments: wellbore storage, intermediate flow, mid-radial flow, crossflow, and systematic radial flow.
• The numerical model accurately determines formation parameters in polymer-flooded crossflow double-layer reservoirs.
• The method effectively evaluates formation damage by comparing interpreted permeability with pre-polymerization permeability.

Conclusions:

• The proposed numerical well testing interpretation model provides a reliable tool for formation evaluation in challenging reservoir conditions.
• This interpretation method demonstrates significant potential for application in enhanced oil recovery (EOR) projects.
• The study confirms the model's efficacy in assessing polymer flooding performance and its impact on reservoir properties.