Abstract
Petroleum Development Oman (PDO) has commenced several Enhanced Oil Recovery (EOR) methods in the Sultanate of Oman to increase recovery from fields with challenging rock and fluid properties. Polymer flood is one of the mature EOR techniques that are currently operated in sandstone reservoirs in the South of Oman.
The reservoir under trial in this paper shares its OWC with another reservoir that has been developed through polymer flood. Although they both share similar fluids with viscosity of ~90cP, the reservoir under trial exhibits significant lower permeabilities, which poses a risk to injectivity. Furthermore, well completions with sand control have shown to be too detrimental to productivity which causes high sand production. This creates a challenge for the polymer flood from both the injectivity and sand control point of view. Thus, a pilot was designed with the following three objectives; test ability to sustain injectivity of polymer into the reservoir, monitor polymer efficiency, and evaluate operational impact on facilities due to sand production that is expected to increase with polymer flood.
The pilot was designed such that two patterns are drilled adjacent to each other where one will be used for the polymer flood and the other pattern serves as a backup in case the first pattern suffers from loss of injectivity or any unforeseen issues. The patterns are inverted five spots with an injector-producer spacing of 75m. The injectors are equipped with fiber optics for data acquisition and real time temperature and acoustic surveillance. The plan is to inject water until a baseline is established, which is then followed by polymer injection for up to one year.
Currently, the project is in the water injection phase where information and data are gathered such as injectivity, conformance, reservoir connectivity in addition to fluids production baseline establishment. This paper presents those findings from the water injection phase in addition to design aspects for the polymer phase.
