Mature Field Revitalization Using Polymer Flooding: Palogrande - Cebú Field Case

Abstract

AbstractIncreasing oil recovery by water injection is the most extended technology in the world; however, excessive water production is one of the main threats for the longevity of oil fields. It results in increased production cost and higher capital investment requirements in surface facilities to produce and handle water. To revitalize mature fields Ecopetrol has taken major steps in applying enhanced oil recovery methods (EOR) and some other technologies. Polymer flooding represents the most common chemical enhanced oil recovery (CEOR) method implemented at field scale as a strategy, increasing oil production and reducing water cut.This work presents the implemented procedure during design, execution and monitoring of the polymer flooding pilot test as a strategy to revitalize Palogrande - Cebú field. Developed strategy for this pilot is described, incluiding operational and reservoir parameters analysis, injection facilities considerations, strategy for increase injectivity, water source characteristics, polymer solution quality (QA/QC) and vertical swept efficiency correction.Polymer injection started in May- 2015. At december 2016, cumulative polymer injection reached 1.6 million barrels distributed between two injectors at a range polymer concentration between 200 – 1500 ppm and injection rates between 2000 – 3200 BPD per pattern. Production initial response has been positive with a cumulative incremental that exceeds the 85,000 barrels of oil with reduction of water cuts of up to 10%. Additionally, no polymer production has been detected in any of the offset producers of pilot injectors.The polymer flooding pilot test have allowed the assimilation of learned lessons, best practices for continual improvement in the operation of such processes, incremental oil production; water cut reduction and increases in the fluid levels for the offset producers. Based on the pilot success, the feasibility of expanding this EOR method is evaluated as strategy to revitalize this field.