Risk Mitigation in Development Drilling Through Improved History Matching by Incorporating Uncertainty Analysis with a Hidden Gas Cap

Abstract

This research paper discusses the Field Development Plan (FDP) - 2020 of a brownfield which recommends drilling 3 infill producers to boost oil production. The study aims to address the mismatch in Gas Oil Ratio (GOR) in the existing model by incorporating uncertainty analysis in the simulation model. The methodology includes a top-down approach through the synthesis of the pressure-production behaviour, the evolution of GOR in wells/fields and the possible presence of a hidden gas cap. The findings of the present study demonstrate that by incorporating a small initial gas cap in the up-dip area of the field that any well has not penetrated, a significant improvement in GOR match and its early evolution in wells/fields are beautifully captured. The introduction of the initial gas cap has necessitated re-positioning and shifting of 3 infill producers away from the gas cap to maximise oil production. A novel two-pronged approach has been recommended for enhancing the water injection rate by 3-4 folds through a combination of a powered water injection system (already in place) and conversion of one of the existing injectors to a dump flooder on a pilot basis to ensure uninterrupted water injection in the field given the frequent power outages in the area.