Recovering Missing Log Data

Missing or incomplete well logs can negatively impact interpretations.

Over the past few years we have been developing log processing and visualization software in support of our geophysical processing / seismic inversion services. What follows is a quick taste of how our polynomial regression technology (PolyFit) can effectively recover missing or incomplete well logs.

The Karewa LAS file was obtained from a New Zealand government website and has been further processed with OpenGeoSolutions proprietary LogView software.

For this example we copied the RHOZ curve into RHOZ_w_Nulls and set a null zone from 2010 through 2060. This is the Black Curve in Track3. The null zone (-999.25 values) shows as a straight line between the remaining live values.

We then calculated the regression coefficients for RHOZ_w_Nulls (the dependent variable) using DTCO, DEP, DTSM and GR as the independent variables from 1800 to 2190. (NOTE- Null zones are not used in the calculation of the coefficients). This process takes a few seconds on a state of the shelf compute node.

We then evaluated (generated) the red Curve on Track3 ( RHOZ_I4_O2_fr_Nulls )......using the regression coefficients and the DTCO, DEP, DTSM and GR curves. The generated red curve shows a very good fit with the Original RHOZ - blue curve within the null zone and black curve outside the null zone.

We have recently added the capability to run similar processing across multiple wells. Besides predicting missing well-log sections we look to derive and provide better well-log systematics across basins and stratigraphic intervals.