Comparison of Condensate Recovery by Hydrocarbon and Nonhydrocarbon Injection

Abstract

The challenge in the development of gas condensate reservoirs is to recover the most valuable hydrocarbon component, "condensate". Pressure drops below the dewpoint anywhere in the reservoir cause condensate dropout. When the pressure drops near the producing wells, condensate banking can occur, which impedes production. Gas recycling is one of the efficient ways of developing such reservoirs because it maintains reservoir pressure and hence increases the condensate recovery. Demand for gas has resulted in a strategy of nonhydrocarbon (NHC) injection in selected areas of the field. An NHC method under study has the potential to raise the dewpoint of the reservoir fluid making it more susceptible to condensate dropout. The objective of this study was to quantify the effect of NHC injection on recovery of condensate and hydrocarbon gas and the effect on productivity of wells. In this study, sector models are extracted from a full field model. The molar recovery of hydrocarbon component and condensate recovery were analyzed under the effect of reservoir properties and distance between wells and injection stream. NHC breakthrough time and tracer modeling were also studied. The NHC under study was found to be inefficient compared to the hydrocarbon injection in all cases; however, the properties of the rock and distance between wells impact the efficiency. The difference in recovery factor at two pore-volume injection with NHC injection was nearly 5% less than that with hydrocarbon injection at pressure 4,700 psi, and this difference increased to 10% at 3,000 psi. NHC is poor in revaporizing the condensate dropped in the reservoir whereas hydrocarbon gas can efficiently revaporize condensate either by first-contact miscibility or by a multicontact miscible process.

Performance Evaluation of CO2 Huff-n-Puff Gas Injection in Shale Gas Condensate Reservoirs

“…The accumulated condensate can be produced during the puff process [18,19]. The efficiency of different gas injection modes has been investigated [20][21][22][23][24][25][26][27][28][29]. The huff-n-puff process consists of three stages: huff (injection), soaking, and puff (production).…”