MWD GR Logs and Perforations

In the early part of the decade perforations were usually split up along the lateral and grouped in large intervals. Over time the laterals increased in length and the number of intervals also increased.

While processing data, I noticed there were preferential perforation clusters where the frac fluid would depart the wellbore and enter the formation. In conjunction with a reservoir engineer we plotted the MWD GR log along the wellbore and events and noticed a pattern where the preferential port was typically in the hotter or shaly section of the stage. The next stage may be more evenly distributed and then the we would see this pattern reappear again later on down the wellbore where there was acute GR changes.

The question we had, were the completion designs not including the logs? It turns out, most were geometrically designed without regard for the geology along the lateral. Later well completions tended to reduce the stage separation and increase the total number of stages/well which helped to reduce the incidents described above, but not by design. This type of analysis takes only moments to produce and is part of a thourogh investigation.