Abstract
The purpose of this paper is to provide a more relevant solution to the diffusivity equation than the conductive disc/zero potential flow (Exponential Integral) solution, especially for use in predictions of the time that is required for an interference effect to reach an observation well. After explaining the assumptions and theory behind the method, a direct integration of the radius of investigation will be presented, along with a physical explanation of what it is. While presenting multiple examples to support the theory, the results from Exponential Integral method for predicting interference arrival at an observation well will be compared. Finally, it will be demonstrated that the classic radius of investigation equation is more appropriate in interference/communication testing, and that rate, gauge resolution, and the total system pressure drop do not affect the arrival of the interference effect.
