When E-Logs are Not Enough and Surface Logging is the Catalyst in Decision-Making: Back to Basics

Summary The paper discusses the role of surface logging in modern drilling operations, emphasizing its value added beyond well control activities and in presence of most sophisticated logging tools. It presents three case studies to illustrate the effectiveness of surface logging in different environments and project phases. Case 1 involves a horizontal development well in the Marcellus play, where surface logging helped identify a marly transition zone between carbonate and shale, allowing for stimulation and production. This interpretation reduced non-stimulable zones significantly. Case 2 describes a gas appraisal well in SE Asia targeting fractured basement. Despite initial interpretations suggesting no viable targets, a review of gas data indicated a gas accumulation, leading to a successful production test. Case 3 analyzes the experience on an exploratory well in the Caribbean offshore. Initial petrophysical interpretations indicated a significant oil column, but surface logging data suggested otherwise. Further analysis revealed fresher water than expected, leading to a revised wireline logging operation with significant cost savings. The paper concludes that while surface logging cannot replace electric logs, its integration with other data sources can close gaps and reduce uncertainties, providing substantial economic benefits.