Calibrating Log-Derived Permeability Data to PTA for Geostatistical Integration into a Fluid-Flow Simulation Model

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOne of the classic problems in the development of a reservoir numerical simulation model is the question of scale. Data that are acquired from many different sources give us a view of the reservoir under different constraints. In this paper, we present a technique that integrates data from the core scale to that acquired through logs to well-test pressure transient analysis (PTA) and, finally, to the production history information. A field example from the Neuquen Basin demonstrates this procedure.PTA offers a reasonable estimate of the permeability within the drainage radius of the well.Unfortunately, these measurements usually are not made in every well. Log data typically is acquired in the field from most wells. Using recovered core data and permeability analysis from cores, a probabilistic petrophysical model, honoring that core data, is constructed. The petrophysical model is applied throughout the field and used in constructing a geocellular model. The model can be investigated in positions equivalent to the volumes investigated by the PTA, and the petrophysicallyderived permeability can be iteratively modified to match the permeability derived from the PTA. The geocellular model is upscaled for dynamic fluid-flow simulation. Finally, the production history is compared with the simulation results. The process becomes an iterative loop to achieve the best match of all the available data. This process facilitates the final history match to gas, oil and water production.

Appraisal of complex reservoirs with short-time tests

“…The consequence of scale as it pertains to estimates of permeability by wireline tests needs to be recognized, for as Haddad et al (2000) note "… localized samples provide an estimate of permeability but not necessarily the global value that would correspond to well productivity." The need to scale-up small-volume tests to the scale at which well performance is to be predicted is also noted in Blekhman et al (2001). Scale-up techniques such as those based on simple layering will be inadequate and flow-based methods will be required.…”