Flow of Polyacrylamide Polymers in the Near-Wellbore-Region, Rheological Behavior within Induced Fractures and Near-Wellbore Areaстатья (материалы конференций)
Аннотация: Abstract The economics of polymer solution injection projects are dependent on the improvement of displacement efficiency over waterflooding, the injectivity of polymer solutions, and reduced lifting costs associated with oil production and reduced water cut. High molecular weight polyacrylamide polymers show shear-thinning behavior when measured in a rheometer while they show shear-thickening behavior in cores. Micromodel experiments were used to investigate the rheological properties of polyacrylamide polymers at the high flow velocity conditions occurring in the near-wellbore region of wells. The results show shear-thickening characteristics. In addition, some plugging of the models by polymers was observed despite filtering of solutions. Also, core flood tests were performed. For the core-flood tests, severe degradation of the polymers was observed for high flow velocities. The data gathered from the experiments was used to interpret the results of a polymer solution injection test performed in the 8 Torton horizon reservoir in Austria. Shear-thickening behavior of the polymers would lead to very high well-head pressures. Through introduction of the degraded polymer viscosity data obtained from the laboratory experiments, the injection pressure observed in the field is explained. The field test showed that after a first phase of polymer solution injection under matrix conditions, a second phase with injection above the formation parting pressure (FPP) exists. To investigate the polymer rheology during this phase, micromodel experiments with various fracture geometries were conducted. The results show that within the induced fractures, polymer solutions show shear-thinning behavior and no substantial degradation of the polymers is seen. Owing to the low flow velocities through the fracture planes into the formation, also within the formation, no severe degradation of the polymers is expected. Hence, high molecular weight polyacrylamide polymers should be injected above the FPP when high flow velocities are expected in the near-wellbore region and such injection is permissible.
Год издания: 2013
Авторы: Markus Zechner, Markus Buchgraber, Torsten Clemens, T. Gumpenberger, L. M. Castanier, Anthony R. Kovscek
Источник: SPE Annual Technical Conference and Exhibition
Ключевые слова: Enhanced Oil Recovery Techniques, Hydraulic Fracturing and Reservoir Analysis, Drilling and Well Engineering
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