Field Demonstration of the Impact of Fractures on Hydrolyzed Polyacrylamide Injectivity, Propagation, and Degradation

This paper confirms theoretical predictions that fractures with limited length and proper orientation can dramatically increase polymer injectivity and eliminate mechanical degradation, through field observations at the Kalamkas oil field in Western Kazakhstan. Step-rate tests and pressure transient analysis confirmed polymer injection above the formation parting pressure. A novel method was developed to anaerobically collect samples of fluids back-produced from injection wells using natural reservoir energy at the wellhead. Rheological measurements of back-produced polymer solutions revealed no mechanical degradation for the Kalamkas conditions. The open fracture area was high enough to ensure low flow velocity within the fracture (keeping the polymer mechanically stable). Contact with the formation rapidly depleted dissolved oxygen from injected fluids, promoting polymer chemical stability. The new back-production sampling method is quick, simple, inexpensive, and reliable.