New research into wellbore modeling and grid generation techniques, has made feasible pressure transient analysis (PTA) based on a numerically simulated solution. This paper first briefly reviews the development, including determination of the gridding and time step control algorithms, and then discusses some of the technical advantages offered by a numerical model as compared to standard analytic solutions. The focus of the paper is on several field case studies. The cases presented involve partial penetration and non-Darcy flow turbulence. Since general analytic solutions for these problems are not available, this paper presents new numerical solutions for these types of problems. For example, isolation of mechanical skin from partial penetration and turbulence effects, as demonstrated in this paper, is an ongoing and critical problem with respect to evaluating the need for reperforation and/or stimulation treatments.
Preliminary findings from ongoing multiple phase PTA research, including modeling production below the bubble point and gas-water coning will also be presented.
The results demonstrate that a simulation approach offers a revolutionary new and completely general solution to evaluating wellbore and reservoir problems that are either very difficult or not currently possible to solve analytically. Proper and practical evaluation of well tests with a numerical approach cam lead directly to bottom line profit making decisions.