Reservoir characterization

Formation Evaluation

The papers explore innovative approaches developed by authors of SPE conference papers toward avoiding data bias, working around the absence of openhole data, and reducing the uncertainty of mass-transport complexes.

Abstract digital graph

This marks the first of two Formation Evaluation features for 2021. This topic, along with EOR Operations and Artificial Lift, had such a high number of devoted conference papers, and a high degree of reader interest, that it was expanded and will appear in the August issue as well. The papers chosen by reviewer Rahul Dastidar explore innovative approaches developed by authors of SPE conference papers toward avoiding data bias, working around the absence of openhole data, and reducing the uncertainty of mass-transport complexes.

Paper SPE 201358 addresses the problem of bias in inverted transverse-relaxation time (T2) distributions in nuclear magnetic resonance (NMR) measurements. The authors discuss two quality-control approaches that are not meant to replace linearly inverted T2 distributions but which can optimize NMR measurements in real time.

The next paper outlines important experience gained in two tight gas fields offshore the UAE for which openhole data were not available for purposes of petrophysical evaluation. The answer, according to the authors of paper SPE 202894, is the use of cased-hole log data. As with the previous paper, the solution is not necessarily offered as a replacement to a conventional approach but as an effective backup solution to a commonly encountered issue.

The third paper explores challenges in petrophysical assessment in a wildcat project in Colombia involving mass-transport deposits. The authors of paper SPE 203016 develop a work flow that integrates NMR, multifunction spectroscopy, borehole images, and radial sonic measurements to overcome the uncertainty of non-Archie rock formations.

As always, SPE authors continue to innovate in the face of challenges both expected and unexpected—a concept with which all of us can identify as of late. I hope these three papers, as well as the other Technology Focus synopses included in this issue, provide insight and inspiration.

This Month's Technical Papers

Two Approaches Provide Quality Control for NMR Measurement of Unconventional Rock

Cased-Hole Standalone Evaluation Succeeds in the Absence of Openhole Data

Formation Evaluation Workflow Assesses Mass-Transport Complex Reservoirs

Recommended Additional Reading

SPE 201281 Full 3D Reservoir Mapping Using Deep Directional Resistivity Measurements by Michael Thiel, Schlumberger, et al.

SPE 201548 Spatially Resolved NMR T2 Distributions for Pore Size, Surface Relaxivity, and Gas Relative Permeability Mapping of Gas Carbonate Reservoirs by Saida Machicote, Eni, et al.

OTC 30450 Understanding Compartmentalization of Deepwater Reservoirs by Robert Charles Shoup, Subsurface Consultants and Associates, et al.


Rahul Dastidar has over a decade of upstream experience as a reservoir engineer, from exploration to development, in Shell. He holds a PhD degree in petroleum engineering from the University of Oklahoma. Currently, he is a reservoir engineer in the Appomattox Development team, with responsibility ranging from new well delivery to field development planning. He is a member of the JPT Editorial Review Committee.