Prediction Of Liquid Recovery From A Gas Condensate Reservoir.

The primary purposes of this research are to (1) predict the behavior of gas condensate reservoirs, and (2) predict the recovery of liquid hydrocarbons from these reservoirs. Factors involved in liquid recovery are fluid phase behavior (retrograde condensation and liquid revaporization), reservoir heterogeneity, perforation strategies, gas injection versus depletion, cross flow between reservoir layers, injection gas fingering, and pattern geometry. First factor is extremely important to predicting liquid recovery from a gas condensate reservoir. In order to evaluate fluid phase behavior, an equation of state material balance compositional model was developed to simulate the condensate liquid recovery from laboratory constant volume expansion (CVE) experiments and liquid revaporization in the reservoir that results from dry gas injection. The second factor was evaluated using a multi-purpose 3 phase, 3 dimensional simulator to predicting gas and liquid recovery for development of two different field areas. The last five factors were evaluated by employing a compositional simulator and multiple sector models. From the work done on this research, it was concluded that: (1) Pseudo component convergence pressure and characterization factor can be estimated from an EOS M-B model. (2) EOS performance is very sensitive to C(,7)+ characterization. Splitting C(,7)+ into multiple pseudo components is necessary and sufficient to match PVT data. (3) A procedure has been devised to adjust the EOS parameters to match CVE data. (4) A procedure has been developed to adjust D-M parameters to reproduce revaporization behavior as simulated by P-R EOS. (5) The largest effect on the performance of a gas condensate reservoir is reservoir heterogeneity and fractional flow variation. (6) Crossflow effects tend to improve liquid recovery from a gas condensate reservoir. (7) Pattern geometry effects are not sensitive with respect to liquid recovery. Gas injection has a more efficient sweeping effect in the five-splot compared to line drive pattern. (8) Perforation strategies can give better performance efficiency on liquid recovery in a gas condensate reservoir which has big variation in permeability between the adjacent layers