Effect of criterion values on the equations for radius of drainage and time for stabilization

Abstract

After the beginning of production, pressure transients propagate outwardly towards the reservoir boundary that changes the pressure around. This introduces the concept of radius of drainage and time to stabilization of a reservoir, The pressure change at the wellbore would be felt at least infinitesimally everywhere in the reservoir. Many authors have defined the radius of drainage and time to stabilization, based on different criterion values that is the percentage of pressure change or flow rate is compared to wellbore condition. The primary objectives of this study are to recognize and evaluate the importance of criterion values for defining the radius of drainage and time to stabilization. A correlation has been proposed that will allow one to determine the radius of drainage as a function of criterion values. The relationship between a pressure criterion and the corresponding rate criterion has also been established. As expected, an estimated value of the radius of drainage varies considerably depending on the suggested criterion The time required to reach the stabilized condition for any reservoir is infinite. In this study an stabilized condition has been defined as that time at which the rate of declining pressure at the well bore becomes negligible. This has lead to generalized fonns oftime to stabilization correlations.