Coring Challenges and Solutions in the YD Oilfield

In the YD Oilfield, early wildcat wells provided only limited core data and there was low core recovery. In order to acquire enough core data and to improve the core recovery in this oilfield, coring challenges were first analyzed, since the coring intervals were prone to break due to existence of dissolved caves and the fact they contained alternating hard and soft formations with high heterogeneity and high H2S. Then, considering these challenges and the practice of coring in this oilfield, a specific coring solution was proposed for the YD Oilfield, that included consideration of aspects of coring tools selection, wellbore preparation, runing in hole, coring parameters optimization, core cutting and pulling out of hole. In addition, this article also demonstrates the coring drilling experiences in Well APP3 and F09. The solution was applied in Wells APP3 and F09,and their core recovery rate in these wells significantly improved. The results indicate that the proposed solution could effectively address the challenges of coring in this oilfield.