This paper summarizes thedetermination ofuncertainties by DST analysis in appraising and developing the ST-X gas condensate field, which is offshore Vietnam in Block 15-1O. Drill Stem Test (DST) results show that the S field has moderate to low permeability, multiple flow boundaries/barriers, and at least 2 PVT regions. | TAÏP CHÍ PHAÙT TRIEÅN KH&CN, TAÄP 19, SOÁ K1- 2016 Appraising and developing ST-X field: determination of uncertainties by DST analysis Vu Viet Hung 1 Mai Cao Lan 2 1 Lam Son Joint Operating Company Department of Drilling and Production, Faculty of Geology and Petroleum Engineering- Ho Chi Minh city University of Technology, VNU-HCM 2 (Manuscript Received on July 05th, 2015; Manuscript Revised on September 30th, 2015) ABSTRACT A subsurface uncertainties is a possible future event, which, if occurs, would affect project objectives either negatively or positively. For any given model or event, the uncertainty is the range of variation of the component parts and possible outcomes. It could be quantified approximately by either analytical model or in a more cumbersome one such as numerical approach. This paper summarizes thedetermination ofuncertainties by DST analysis in appraising and developing the ST-X gas condensate field, which is offshore Vietnam in Block 15-1O. Drill Stem Test (DST) results show that the S field has moderate to low permeability, multiple flow boundaries/barriers, and at least 2 PVT regions. To understand the impact of these and other important reservoir parameters on ultimate gas and condensate recovery and well count, the uncertainties has to be well evaluated and understood. The study demonstrates that there is a wide range of possible ultimate gas and condensate recoveries and well counts. The top causes for this wide range are permeability and flow boundaries/barriers. In addition to the subsurface risks, drilling cost of a ST-X well is very high. The high well cost in combination with the field being offshore, having low permeability and possibly numerous reservoir compartments dramatically increase the risk of a full field development. Key word: uncertainty analysis, well test analysis, history matching, sensitivity analysis. 1. INTRODUCTION The ST-X field is in the Cuu Long basin with approximately 155 km east of Vung .
