Abstract
Significant fluid property variation can be induced due to pressure and temperature dynamics in the reservoir associated with oil production. The existing analytical solutions for temperature transient analysis generally assume constant fluid properties, which can be invalid especially for cases of high drawdown and strong temperature signals. In this study, we present a method to account for the fluid property variations in temperature transient analysis. The method introduces corrections on fluid property values as input for analytical solutions. The corrections are performed on four identified fluid properties in an iterative manner which can be easily implemented in available temperature analysis procedures. To validate the developed approach, we model drawdown and buildup transient temperature signals with the fluid property correction method for non-damaged and damaged reservoirs under different production rates and reservoir fluid compositions. The analytical modeling results are compared with numerical simulations. In addition, by finding the dominating fluid property, a simplified approach of property correction is presented. Through application to example problems, we show that using fluid property correction method presented herein can improve the permeability estimations by 60% for the conditions considered in this paper. We present a modified method to damaged reservoirs which results in additional 25% improvements on the permeability estimations. With these improvements, the applicability of temperature transient analysis using analytical solutions can be extended from cases with limited sandface temperature signals of a few degC to stronger signals of 20-30 degC.
