OPAL: On Surface Petrophysical Analytical Logging—New Petrophysical Measurement Principles on Drilling Cuttings While Drilling
The OPAL is a standalone unmanned unit, collecting cuttings from the possum belly and analyzes them in a close system. The system produces real time well log curves, which are comparable to open hole logs. This article will show comparisons of examples of OPAL logs side by side with logging while drilling/measurement while drilling (LWD/MWD) logs and open-hole wireline logs. Higher resolution formation measurements will be presented as a case study, where measuring gamma ray (GR) response of slow moving drilling cuttings producing high statistical measurement results and better delineation of Sandstone in comparison to MWD/LWD logs. A case study will present how the logged GR on OPAL, and relatively earlier GR responds of MWD/LWD in shale, detected the potential well cleaning problem. The log difference is an indicator of missing shale cuttings in the well; this effect is confirmed by a decrease in the flow density curve, and an early alert of dangerous drilling conditions was issued. This can prevent a possibility of getting the drill pipe stuck, as well as other drilling issues. Gamma spectrograph is performed by having the sensors placed in direct contact with the cuttings. Example curves will be presented. Case study of resistivity of the hydrocarbon bearing sandstone recorded is higher in upper part than in the lower part of Sandstone, representing the water saturation (Sw) change and correlation to the gas log. Other outputs are:
This device tested on CBM in Canada and Texas on Risco well.
AAPG Datapages/Search and Discovery Article #90219 © 2015 GCAGS, Houston, Texas, September 20-22, 2015