First Ever Polymer Flood Field Pilot - A Game Changer to Enhance the Recovery of Heavy Oils on Alaska’s North Slope

摘要

The development pace of Alaska's vast, 20-25 billion barrels, heavy oil resources has been very slow due to high development costs and low oil recovery using conventional waterflood, and the impracticality of deploying thermal methods due to the presence of continuous permafrost. Although, polymer flooding has attracted attention and has become a promising EOR technique in heavy oil reservoirs due to the extensive application of horizontal wells and advancement of polymer flooding technology, no field tests have been performed to date in Alaska's underdeveloped heavy oil reservoirs. The overall objective of this research is to perform a field experiment to validate the use of polymer flooding for extracting heavy oil in Alaska's challenging environment. Two pre-existing pairs of horizontal injection and production wells in an isolated fault block of the Schrader Bluff heavy oil reservoir at the Milne Point Field are currently being used for the field experiment. Hydrolyzed polyacrylamide (HPAM) polymer injection started on August 28, 2018 at 600 ppm (4 cP viscosity) concentration ramping up to 1,800 ppm (45 cP viscosity) over a three week time period, and has been maintained at an average concentration of ~1,800 ppm. Current injection rates in the two horizontal injectors are ~2,200 and 600 bwpd. Laboratory experiments to determine the polymer retention, optimum water salinity, synergistic effects of water salinity and polymer, and handling of produced fluids, in support of the field experiment, are currently ongoing. Similarly, reservoir simulation of coreflood behavior and history match of previous waterfloods to predict polymer flood performance in the project area are also conducted in parallel. The field data and scientific knowledge that have been collected since the start of the injection indicates that the field pilot is performing as predicted. To date, no unexpected injectivity issues or polymer breakthrough have been encountered, and the two horizontal producers are showing positive response to the polymer injection, resulting in incremental increase in oil production rate. Since the research is still in its early stages, selected field, laboratory and simulation results are presented and discussed to highlight the integrative approach adopted in this first ever polymer flood field pilot in Alaska.