Application of gas-assisted gravity drainage (GAGD) to improve oil recovery of Rang Dong basement reservoir

Abstract

As an option to improve the ultimate oil recovery factor of the Rang Dong field, a feasibility study of gas-assisted gravity drainage (GAGD) application was carried out for the fractured basement reservoir with a single-well Huff ‘n’ Puff pilot test applied on a high water-cut producer. This paper aims to provide an in-depth understanding about such case study, which includes details on candidate selection, gas injection scheme, on-site execution, results of flow-back, post-job review and lessons learned. The pilot test of GAGD was recorded with a good oil rate and low water-cut during flowing back after gas injection and shut-in for gas segregation, which suggests the positive effectiveness of GAGD to some degree. The expansion of the GAGD application to other wells and areas in the field would be encouraged in any similar situation. On the other hand, the results of this pilot test shed a light into further optimisation of the candidate selection and gas injection scheme by material balance analysis and reservoir simulation respectively.