Abstract

A central Oman oil field was evaluated for the potential of an ASP flooding development. The field is a sandstone reservoir containing medium to light oil of 33° API with a viscosity of 9cP.

Till today, the field is under natural depletion with, lately, pressure supported by water injection into the aquifer at the NW and SW flanks. The recovery factor is already high and currently the field water cut is at 97%.

Recently, an EOR screening study was conducted on PDO's fields and the subject field was found to be one of the potential candidates for ASP flooding. Several lab experiments were conducted on reservoir rock and fluid samples to assess the potential of an ASP application. The ASP formulation was tested on two wells in this field through the Single Well Chemical Tracer (SWCT) test technique where the residual oil reduced from 20% to 4% for one well and from 15% to 8% for the other.

Different development scenarios were evaluated: a scenario that makes use of the strong bottom aquifer in combination with horizontal injectors near the OWC was found to be a technically viable development option. The liquid rate forecasts were subsequently used in the project economics showing that the company's screening criteria were met.

The full field development versus phased development approaches were also evaluated where the latter was found to be favorable as it allows for early starting and proper de-risking for following phases. The subsurface feasibility study for this reservoir revealed that there is an opportunity of increasing the Recovery Factor of this field by more than 10%.

This paper will describe in detail the study and the overall de-risking strategy with its various phases namely; lab experiments, single well tests, full field evaluation and showing of commercial attractiveness and finally the optimized implementation through phasing.

You can access this article if you purchase or spend a download.