The equations for laminated isotropic sand—anisotropic shale depositions are well known. PowerLog® now offers a graphical way to view these equations and overlay the well data on the graphs for analysis. The process is highly interactive. Adjusting either the Red dot or Blue dot causes the overlay to move around and blue Sw numbers to change on the Vsh vs. PHIT plot.

Graphical representation of the effect of shale anisotropy. You can move the red dot on a NW/SE trajectory to fit the data points, which indicates the level of anisotropy present. The Blue dot can be set to Ro. The black curves are the Vsh values, while the red curves represent the Rsand values.

The user can move the left and right vertices of the Vsh v PHIT plot up and down to fit the overlay onto the data.

The Laminated Sand-Shale Analysis application is adopted from Baker-Hughes' LSSA program. Used with 3DEX™ multi-component induction logs, LSSA produces saturations and porosities in electrically isotropic and anisotropic sand-shale intervals. The Thomas-Steiber sand-shale model is central to LSSA's partitioning of the formation into sand and shale bed fractions.

Once these inputs are used to correct resistivity for anisotropy then saturation of the sand beds is computed.You can now easily see your thin, laminated bed pay more clearly with PowerLog's LSSA product.

LogPlot showing anisotropy effects on Sw.