Paper: Application of a Light Weight Cement Slurry for Naturally Fractured Formations

The Mesa Verde formation is highly naturally fractured and varies in depth from 5500" to 6200". Low recoverable reserves make wells in this area marginally economical. The lower hole is air drilled and cemented back to the intermediate at 3700 feet. Historically, the production casing has been cemented with a 50/50 Poz/H blend mixed at 13.2 ppg. Bond logs were often marginal and fall back was a problem. This paper reviews the development of a lightweight cement system with the ability to develop high compressive strength to enhance the mechanical seal. This slurry needed to have plating lost circulation material (LCM) to prevent fall back and minimize node buildup due to high fluid loss. Compressive strength, fluid loss and rheological properties for various formulations are presented. The results of over forty jobs are summarized with operation and bond log results reviewed in detail from two typical wells.