The Reservoir Protection Mechanism of Underbalanced Drilling Operation
ZHANG Guangyin1, ZHAO Xiangyang2, YANG Shunhui2, DOU Ninghui2, XIA Bairu1
1. School of Engineering & Technology, China University of Geosciences, Beijing 100083, China;2. Sinopec Research Institute of Petroleum Engineering, Beijing 100101, China
Abstract:The current research status on the underbalanced drilling operation at home and abroad is systematically summered. The reservoir damage mechanism and during the normal process of underbalanced drilling operation, the reason making well bottom reservoir run into intermittent overbalanced drilling operation status caused by drilling operations, such as tripping, logging, and well completion, are analyzed. Intermittent overbalanced drilling operation causes the seriously reservoir damage due to the intrusion of the solid phase, water trapping, and water sensitivity. The technology and the reservoir protection mechanism of underbalanced drilling operation from open reservoir to reservoir production are discussed. Finally, the advantages of underbalanced drilling operation, involving reservoir protection, the reduction of lost circulation and other drilling accident, production increase, quick, real, and exact discovery of reservoir, and evaluation of reservoir, are illustrated by taking wells QX3 and QX4 as the example.