Assessment of Condensate Recovery Improvement Through Gas and Water Injection: A Case Study for a Large Heavily Depleted Very Rich Gas Condensate Field in the Sultanate of Oman

Abstract

The Barik Deep clastic gas reservoir was discovered in 1991 and has been on production since 1994. It is a very rich gas condensate reservoir with initial Condensate to Gas Ratio (CGR) of 1100 m3/MMm3. With reservoir pressure dropping below dew point (428 bar vs. initial pressure of 478 bar), a huge volume of condensate has dropped-out inside the reservoir as confirmed by production data and the deterioration of well performance. As of 1/1/2018, the Barik Deep reservoir is developed with 29 gas producers out of which 7 wells are closed-in mainly due to liquid loading. The reservoir is currently producing above 2 MMm3/d of gas and ~400 m3/d of condensate and reservoir pressure is around 230 bars. An integrated subsurface-surface study was started in 2017 with the objectives ∘To propose an integrated plan for re-developing the Barik Deep∘To identify solutions to maximize recovery of the dropped-out condensate∘To resolve condensate banking issues and its impact on productivity∘To identify new technologies allowing to increase production, to increase the field recovery (gas and condensate) and to propose a maturation plan for these technologies. In a first phase of the project, a detailed analysis of all data collected over years of field development have been used to achieve a step enhancement in the understanding and characterization of the condensation process in Barik deep. In a second phase, the study involved the construction of compositional model capturing the physics of the condensation phenomena (i.e. very refined single well models) in order to assess various condensate recovery options. This effort supported the later building of full field simulation models to evaluate the impact of the most promising recovery techniques on recovery at field scale. This paper covers: The interdisciplinary novel data analysis workflow approach followed to determine the critical elements of the condensation process (PVT, SCAL, pressure depletion, reservoir properties,...etc)The quantification and characterization of condensation by using analytical methods (Pressure Transient Analysis, PVT and production data analysis)The evaluation of various condensate recovery options (CO2, N2, separator gas, water injection and cyclic gas injection) using very refined single well physics based modelsThe evaluation of condensate recovery options using full field models adapted from these physics based modelsThe economical evaluation of condensate recovery optionsThe proposed road map for maturation of the most promising options It is concluded from the conducted study work that out of the various injection fluid options considered, CO2 injection is likely to be the most favorable. Moreover, initial economical screening appear to be promising for CO2 injection.