The leading type of transient pressure test in onshore fields of Sergipe-Alagoas Basin is the so-called Simplified Pressure Test (SPT). Its name stems from the fact it boasts an extremely lean downhole completion (a set of tubings and a production packer). Additionally, it does not require any flow measurement device. From an operational standpoint, all it takes is to settle the packer and let the downhole gauge record the pressure diffusion. It is as simple (and cheap) as that. Not surprisingly, the SPT has become the preferred well-testing choice for the financially-constrained onshore mature fields from Sergipe-Alagoas Basin.
In this paper, we write a mathematical model for the pressure diffusion taking place during a SPT and show that, by coupling Peres Integral Method and Gladfelter Approximate Deconvolution, wellbore storage effects can be successfully removed, unveiling the flow regime taking place within the porous medium. Moreover, we propose a pressure extrapolation technique to be employed when the SPT is performed on low-permeability reservoirs.
Field examples provide compelling evidence that, by following the outlined procedure, an operation as simple as the SPT can indeed provide reliable information at a relatively low cost.