New Software for Well-to-Well Correlation of Spectroscopy Logs

Mirowski, Piotr¹, Michael Herron², Samuel Fluckiger², Nikita Seleznev², David McCormick³, (1) Courant Institute, New York University, New York, NY, formerly with Schlumberger-Doll Research, Ridgefield, CT (2) Schlumberger-Doll Research, Ridgefield, CT (3) Schlumberger-Doll Research, Cambridge, MA

Wireline geochemical concentration logs are becoming common in many oil fields. To take advantage of this, a new standalone PC application with a user-friendly graphical inter­face, Well2Well, enables a new type of well-to-well correlation application with several major innovations.

First, the data that are used are the real values of the chemical concentrations of the most important rock-forming chemical elements. The full list available includes elements from the Elemental Capture Spectroscopy (ECS) and Natural Gamma Ray Spectroscopy (NGS, HNGS) sondes. This is in contrast to the traditional use of gamma ray/spontaneous potential and resistivity data, which are at least as sensitive to the fluids as to the rock. Second, elements that are believed to be more geologically important can be included in the analysis and weighted in significance according to the users preference, while less impor­tant trace elements such as thorium and uranium, which are major components of the gamma ray, may be excluded. Third, the input logs can be preprocessed and smoothed with edge-preserving algorithms in order to make the correlation algorithm more stable.

These well-to-well depth correlations rely on the Dynamic Programming algorithm, which computes a chemical signature mismatch matrix between a pair of wells and then finds the best correlation path thanks to an optimal path search through that matrix.

Tests on multiple datasets from US land and Middle East have showed extremely precise well-to-well correlations on wells separated by several hundred meters thus making our software a very promising geological modeling tool.