Analysis and Simulation of Polymer Injectivity Test in a High Temperature High Salinity Carbonate Reservoir

Area of Science:

• Petroleum Engineering
• Chemical Enhanced Oil Recovery (CEOR)
• Reservoir Engineering

Background:

• Polymer flooding is a successful CEOR method, but predicting polymer injectivity in porous media is challenging due to non-Newtonian fluid behavior.
• In-situ rheology can exhibit complex shear-dependent behavior, including shear thickening and thinning, which is difficult to ascertain from field data alone.
• Field applications typically provide limited data, primarily well bottom-hole pressure (BHP).

Purpose of the Study:

• To analyze BHP data from a field polymer injectivity test in a Middle Eastern heterogeneous carbonate reservoir.
• To investigate the impact of flow rate and polymer concentration on injectivity under high-temperature and high-salinity (HTHS) conditions.
• To model and simulate the injectivity test using a single-well model incorporating complex rheology.

Main Methods:

• Analysis of BHP data from a field polymer injectivity test.
• Development of a single-well model to simulate the injectivity test.
• Sensitivity analysis of injection flow rate and polymer concentration.
• Incorporation of complex rheology (shear thickening and thinning) into the model.

Main Results:

• Polymer injection showed a non-linear pressure increase and longer transient behavior compared to water injection.
• Water injection exhibited a linear pressure response to rate variations and quick stabilization.
• The best match between simulation and field data was achieved using a complex rheology model, combining shear thickening near the well and shear thinning further away.

Conclusions:

• Complex rheology, including shear thickening and thinning, is critical for accurately modeling polymer injectivity in HTHS reservoirs.
• BHP data analysis combined with appropriate rheological models can improve the prediction of polymer flooding performance.
• Understanding in-situ rheology is key to optimizing polymer flooding strategies in challenging reservoir conditions.