This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199023, “Evaluation of Well Performance Using Data From Fiber-Optic Sensors in Wells of a Pilot Polymerflooding Test, Orinoco Basin, Venezuela,” by Andres Ramirez, Edgar Vasquez, and Luis Quevedo, PDVSA, et al. The paper has not been peer reviewed.

The complete paper describes a pilot test using polymerflooding in which evaluating the performance of injector wells was a main priority. The authors chose to complete the wells using a distributed temperature sensor. The paper describes how a better understanding of the connection between the well and the reservoir can improve reservoir simulation models, the decision-making process, and well-performance evaluation. The authors also stress the importance of determining the possibility of unswept areas in the reservoir, which could result in low volumetric sweep efficiency and, consequently, low recovery factor.

Introduction

The field is in the Orinoco Belt, mainly unconsolidated Miocene sandstone, and has produced heavy oil since 1999. At the time of writing, more than 711 producing wells have been drilled since the beginning of the exploitation of the field. After reaching a production plateau of 200,000 B/D, enhanced-oil-recovery technologies have been considered. One of these is polymerflooding.

A pilot test was conducted in an area of the field in which conditions did not indicate application of any thermal recovery technique. The reservoir pressure at project startup was 315 psia, with a reservoir temperature of 115.5°F. Average porosity was 0.32, reservoir absolute permeability was estimated to be between 25 and 15 darcies, and reservoir thickness was 25 ft. Oil mobility was very low because of high viscosity.

The pilot test began in 2016. Polymer at a concentration of 900 ppm was injected in a deltaic sedimentary environment composed of distributary channel fills and mouth bars. Polymer was injected through three injector wells.

The objective of the test is to provide rapid answers to questions about injection performance, polymer stability, and the effect of heterogeneities. The results will determine if the technology represents a feasible opportunity for future development of the field. The objectives of the control plan in this phase include the following:

- Establish how much of the horizontal section contributes to the well injectivity

- Estimate an injection profile distribution

- Determine if important changes occur during injection

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