Qualification of New Methods for Measuring In Situ Rheology of Non-Newtonian Fluids in Porous Media

Area of Science:

• Petroleum Engineering
• Fluid Mechanics
• Materials Science

Background:

• Traditional linear core floods for in situ rheology measurements assume steady-state conditions.
• Radial flow presents non-linear pressure and shear-force gradients, requiring advanced rheological analysis.
• Potential experimental artifacts in polymer rheology, like shear-thinning, may stem from pressure measurement inaccuracies.

Purpose of the Study:

• To validate new methods for in situ rheology measurement in radial flow experiments.
• To quantitatively assess the robustness of these methods against pressure measurement errors.
• To investigate polymer memory and rate effects in porous media using radial flow data.

Main Methods:

• Performed radial polymer flow experiments using partially hydrolyzed polyacrylamide (HPAM) in Bentheimer sandstone.
• Utilized distributed pressure ports for detailed radial pressure variation analysis.
• Conducted generic simulation studies to quantify the impact of pressure measurement error on in situ polymer rheology.

Main Results:

• History match methods demonstrated robustness against typical radial flow pressure measurement errors, showing negligible deviations.
• Significant deviations in rheology were observed only when pressure error levels were five-fold higher than typical.
• Rheology curves from history matching the radial experiment overlapped, indicating no geometric influence on the in situ rheology of the investigated HPAM.

Conclusions:

• The developed methods are reliable for in situ rheology measurements in radial flow, even with common pressure transducer inaccuracies.
• Polymer memory effects can be evaluated at the Darcy scale in radial flow experiments.
• For the studied HPAM, in situ rheology is independent of geometry, and shear-thickening onset is independent of injection rate in radial flow.