Innovative Integrated Workflow to Reduce Uncertainties and Improve Hydrocarbon Recovery

Abstract

In producing fields, re-mapping reservoir fluid content and new contacts are one of the most important objectives in pursuit of optimized well productivity. Wireline logs and formation testing (FT) data is widely used for this purpose. Continuous fluid data from Advanced Mud Gas (AMG) analysis with downhole logs can be used to generate a comprehensive dataset for reservoir evaluation. Each method has its limitations and advantages. Combining and interpreting the output from the fundamentally different datasets require an experienced petro-technical expert with a specific skill set. To calculate hydrocarbon volume, estimate and forecast reserves, formation fluid evaluation has primarily relied on traditional methods that depends heavily on formation pressure measurements. This was achieved through the analysis of gradients and local fluid contacts. This approach can be misleading for brownfields, where a sizable amount of producible hydrocarbon is left in the reservoir. For characterizing formation fluid, a novel approach utilizing complimentary technologies was adopted. For early hydrocarbon detection and FT program optimization, AMG data was first gathered while drilling. Post drilling open Hole logs, formation pressure and fluid data were acquired not only to verify the AMG findings but also to fill in the gaps regarding water-swept zones, reservoir pressure and depletion, exact fluid contacts, and fluid characteristics to reduce uncertainties. During the job execution, AMG data was effectively used to provide early formation fluid identification and contacts. This information was used to optimize the wireline advanced fluid analysis stations. AMG analysis identified multiple fluids (wet gas, gas condensate, oil, and water) and revealed a much greater complexity of the reservoir than initially expected, which could not have been achieved with standard formation evaluation or other fluid contact identification techniques based on regional gradient analysis. The fluid types and contacts identified by AMG were then confirmed by the wireline downhole fluid analysis. Using this workflow, a high potential recoverable hydrocarbon oil was identified over a reservoir that was classified as a water zone based on initial evaluation and knowledge. In this field, an innovative method was adopted for reservoir fluid characterization. This approach based on digital integration and a unified workflow was used successfully for fluid contact identification, targeted fluid sampling, and identifying and recovering more hydrocarbon from the swept zones.