Successful Polymer Gels Application in a Highly Channeled Peripheral Injection Well: Tello Field Pilot

Abstract

Abstract Tello Field is operated by ECOPETROL S.A. and located in the Upper Magdalena Valley Basin, Colombia. It began production in 1972 and reached a maximum primary rate of 11, 200 BOPD in 1980. A peripheral water injection process started in 1997, reaching a maximum secondary production of 15, 552 BOPD in 2000. From this date, water production has increased due to an unfavorable mobility ratio (M > 3.5) and a high permeability contrast (Dykstra-Parson coefficient: 0.8 - 0.9). The current recovery factor is 22% and water cut is 92%. This paper summarizes from the laboratory to the field evaluation of a successful polymer gel project for controlling water thief zones, implemented as a strategy to reduce the phenomenon of channeling identified between the injection well Te-49 and the producer well Te-46. The design includes laboratory test (fluid – fluid, fluid – rock and cinetic reaction) to determine the right polymer and the necessary polymer and crosslinker concentration to obtain consistency of the gel at the reservoir conditions. Polymer gel injection began in October 2009, reaching 43, 400 bbl of solution injected (13% of channel volume) and being the largest Latinoamerican polymer gel treatment until now. Injection strategy considered a maximal polymer concentration of 7000 ppm and a fixed polymer/crosslinker ratio ranging from 40:1 to control maximum injection pressure. Field results showed an important increase in oil recoveries (oil production up to 300%) and a reduction in water cut (3%). Comparing these results to what is normal obtained with this technology this is one of the most efficient process until now, this is more relevant when taking into account the peripheral condition of the water injection. This work led to design and implement processes for water injection channeling control to improve the efficiency of water injection into other areas of the Tello field and other Colombian fields.