Selecting EOR Polymers through Combined Approaches-A Case for Flooding in a Heterogenous Reservoir

Area of Science:

• Petroleum Engineering
• Polymer Science
• Reservoir Engineering

Background:

• Heterogeneous reservoirs pose challenges for enhanced oil recovery (EOR) due to complex flow paths.
• Polymer flooding is a common EOR technique, but polymer selection is critical for success.

Purpose of the Study:

• To evaluate polymer behavior and identify key selection criteria for heterogeneous reservoirs.
• To assess the impact of polymer molecular weight distribution (MWD) on injectivity and displacement efficiency.

Main Methods:

• Utilized two-layered micromodels simulating heterogeneous sandstone.
• Conducted single- and two-phase core flooding experiments at various velocities.
• Employed Field-Flow Fractionation (FFF) to characterize polymer properties like MWD and gyration radii.

Main Results:

• Polymers with narrower MWD (A and C) showed better injectivity and lower retention in single-phase flow.
• Polymer B, with the highest MWD, exhibited poor injectivity and high adsorption in two-phase flow.
• FFF analysis correlated well with micromodel and core flood results, highlighting MWD's importance.

Conclusions:

• Full spectrum MWD measurement using FFF is essential for predicting polymer performance.
• Heterogeneous micromodel and core flood evaluations provide reliable data for field application polymer selection.
• Narrower MWD polymers demonstrate superior injectivity and sweep efficiency in heterogeneous reservoir conditions.