Reservoir formation failure and sanding prediction for well-construction and completion design

Some of the approach and analysis procedures that were applied in the Judy/Joanne field to overcome sanding problems are discussed. Investigators examined the problem using a systematic rock mechanics approach to find an improved completion solution for new wells. Two well cores from Well 30/7a-7 (Judy) and Well 30/7a-P3 (Joanne), provided representative reservoir sandstone samples for sand strength determination and sanding evaluation. Both cores were sampled and tested using a manual load frame and a penetrometer for unconfined compressive strength (UCS). Judy sand strength has 2,000-7,100 psi or higher UCS. Nearly 50% of the samples tested had UCS lower than 3,000 psi. Core segments were selected for triaxial testing and multiple plugs were used to determine stress-strain relationships and failure criteria. These data were then analyzed to define the non-linear material laws and critical plastic strain failure limits for formation failure and sanding prediction.