Gas condensado

TECHNOLOGY FOCUS

Well Testing
The advent of computer-aided analysis, derivatives, and deconvolution over the last 3 decades produced a dramatic change in the way we looked at well testing: from a mere well-performance indicator to a powerful reservoir-characterization tool. Well testing is a technical “masterpiece” when it comes to the assessment and exploitation of complex reservoirarchitectures and frontier assets. Yet, multiple challenges lie ahead of us, from ultradeep wells to subsea subsalt developments with increasing environmental concerns; these are indeed exciting times for the field. This brings me to the theme of this feature. Well-test analysis continues to push the boundaries of reservoir characterization on all fronts, leading to improved interpretation techniques forunconventional resources, intricate deepwater test programs, and accelerated use of high-resolution-simulation models. In the early 1960s, we would, literally, calculate permeability and skin by use of straight lines on a graph with a pencil. Nowadays, and with the help of better gauge metrology, we are opening a new chapter in the use of well testing for reservoir characterization and proactivefield management. Some people have even suggested that we should expand the definition of well testing to include measurements other than pressure. Take, for instance, temperature. Technologies such as distributed-temperature sensing are maturing at a relatively rapid pace, bringing more insights into dynamic-flow description. As well testing strives to advance and overcome the enormous challengesof today, we need to take a moment and peek outside our tree to see the forest. The papers selected for this feature and those in the reading list are a clear illustration JPT of these latest endeavors. I hope that you will find them of interest.
Well Testing additional reading available at OnePetro: www.onepetro.org SPE 123982 • “A New Pressure/Rate Deconvolution Algorithm To AnalyzeWireline-Formation Tester and Well-Test Data” by Evgeny Pimonov, Schlumberger, et al. OTC 19767 • “Use of Dynamic Simulation To Refine Well-Testing Procedures and Optimize the Data Required for Deconvolution Techniques” by J.C. Mantecon, SPT Group, et al. SPE 124271 • “The Value of Well Testing—Optimization of the West Brae Field” by Mike Tharagonnet, SPE, Marathon Oil

Renzo Angeles, SPE, is a SeniorResearch Engineer with ExxonMobil Upstream Research Company. He has 9 years of petroleum engineering experience, receiving training in Peru, Colombia, Ecuador, USA, and Canada. Previously, Angeles was a field engineer for Schlumberger. Currently, he works with the subsurface technology division supporting ExxonMobil’s global exploration, development, and production affiliates. Angeles’ areas ofinterest include well testing, pressure-transient analysis, formation testing, near-wellbore modeling, petrophysics, and subsurface engineering. He holds MS and PhD degrees in petroleum engineering from the University of Texas at Austin. Angeles serves on the JPT Editorial Committee.

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JPT • FEBRUARY 2010

WELL TESTING

Practical Solutions for Pressure-Transient Responses of FracturedHorizontal Wells in Unconventional Reservoirs
An analytical trilinear-flow solution was developed to simulate the pressuretransient and production behavior of fractured horizontal wells in unconventional reservoirs. This solution provides an alternative to rigorous solutions, which can be cumbersome to evaluate. These solutions provide insight about and the conditions leading to these flow regimes.Identifying these flow regimes is important to characterize unconventional reservoirs from pressure-transient tests.

Outer reservoir Hydraulic fracture

Inner reservoir: Naturally fractured

Introduction Although it is possible to develop detailed analytical models to represent transient fluid flow toward a multiple-fractured horizontal well in tight unconventional reservoirs such as shale,...