Predicting performance of gas condensate reservoirs

Abstract

Multiphase flow behavior in gas condensate reservoirs is analyzed, and in particular estimating gas condensate well deliverability. Inflow performance relationship (IPR) measures for gas condensate wells are analytically generated and made available. The inflow performance relationship measures of gas condensate wells incorporate the effect of condensate banking as pressure near the well bore drops below the dew point. The inflow performance relationship measures are based on formation rock relative permeability data and Constant Composition Expansion (CCE) experiment data.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Application No. 61 / 724,534, filed Nov. 9, 2012. For purposes of United States patent practice, this application incorporates the contents of the Provisional Application by reference in entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to reservoir analysis of performance of subsurface hydrocarbon reservoirs, and more particular to prediction of the performance of gas condensate reservoirs.[0004]2. Description of the Related Art[0005]Gas condensate reservoirs differ from dry gas reservoirs. Understanding the phase and fluid flow behavior relationships has been required in order to make accurate engineering computations for gas condensate systems. Condensate dropout occurs in the reservoir as the pressure falls below the dew point. As a result of such condensate dropout, gas phase production from gas condensate wells decreases signifi...

AI Technical Summary

Benefits of technology

The present invention provides a data storage device with instructions for a computer system to predict the performance of a gas condensate well in a subsurface reservoir. The system receives data on the composition of the well's fluid, the permeability of the formation containing the gas condensate, and the pressure of the well. The system calculates the gas condensate's dew point and checks if the well's pressure is above it. If the pressure is not, the system estimates the gas condensate's productivity index for single and two-phase flow and predicts the well's performance depending on the formation's permeability and the productivity index. If the pressure is above the dew point, the system estimates the well's performance based on the pressure and the formation's gas permeability. The estimated performance is then saved in memory. Overall, this invention allows for better understanding and prediction of gas condensate well performance.

Problems solved by technology

As a result of such condensate dropout, gas phase production from gas condensate wells decreases significantly.

Well productivity is an important issue in the development of most low and medium permeability gas condensate reservoirs.

Liquid build up around the well has been found to cause a significant reduction in productivity, even in lean gas condensate reservoirs where the maximum liquid drop out indicated by test data is as low as 1%.

However, accurate forecasts of gas condensate productivity has been difficult because of the need to understand and account for complex processes that occur in the near-well region.

So far as is known, none of these estimation methods have been simple to use.

Images