In-Depth Water Conformance Control: Design, Implementation and Surveillance of the First Thermally Active Polymers Treatment TAP in a Colombian Field

Abstract

The Yariguí-Cantagallo is a mature oil field located in the western flank of the middle Magdalena valley basin in Colombia. Oil production started in 1941 and has been supported by water injection since 2008 with the aim of maintaining the pressure in the reservoir and increasing oil production. However, due to the channeling of the injected water, the water cut in some wells has been increasing, reaching values greater than 90%. Therefore, ECOPETROL S.A. implemented the first deep conformance treatment in Colombia through the design, execution, monitoring and evaluation of the technology in the YR-521 and YR-517 patterns for improving sweep efficiency of the waterflooding process. Brightwater® technology (also known as Thermally Active Polymer, TAP) has been used as an in-depth conformance improvement agent in reservoirs under waterflood suffering from the presence of thief zones or preferential flow channels. BrightWater® consists of expandable submicron particles injected downhole with a dispersive surfactant as a batch using injection water as a carrier. The selection of the injection patterns and treatment volume estimation was carried out through analysis of diagnostic plots and analytical pattern simulations. Treatment design and chemistry selection were based on reservoir characteristics, especially the temperature profile between the injector and offset producing wells in each pattern. Thus, laboratory tests with the representative fluids at various temperatures were carried out. Injection in the first pattern began on December 14, 2020, with a cumulative 6344 bbls of water containing TAP, at an injection rate of 700 bpd, gradually increasing the concentration from 3,500 ppm to 12,000 ppm. Once the injection was completed in this pattern and using the same surface facility, the second injection pattern was executed, on December 23, 2020. In the second pattern a cumulative of 9152 bbls of water containing TAP was injected at an injection rate of 700 bpd at concentration from 3500 ppm up to 8000 ppm. This paper summarizes the first TAP pilot implementation in Colombia and will describe the methodology and results of project QAQC monitoring and injection-production. Based on results to date, after one year monitoring (decrease in water cut up to 6%, in some wells, with consequent increase in oil recovery up to 18,642 STB), five additional treatments are planned in other injection patterns in this field between 2022 and 2023. It was validated that the deep conformance improvement technology allows blocking the preferential flow channels, reaching new areas with high oil saturation. Incremental oil production, potential increase in reserves, and reduction of OPEX due to lower water production were some of the observed benefits from this trial. Likewise, calculations show positive impacts in reducing the carbon footprint and water management.