Complete Digital Workflow Drives Deep Transient Testing in Greenfield Exploration
Authors: Carpenter Chris 
Published: February 2025

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 24454, “Driving Deep Transient Testing With a Complete Digital Workflow: A Sustainable Exploration in Greenfields,” by Dennis Ling, SPE, Saifon Daungkaew, SPE, and Morten Kristensen, SPE, SLB, et al. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference.

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Deep transient testing (DTT) is a wireline-formation-testing technique investigating higher permeability and thicker reservoir packages with increased radius of investigation compared with traditional interval-pressure transient testing (IPTT) by flowing faster and longer and by using higher-resolution pressure gauges. The complete paper presents a digital workflow applied to several greenfields in the Asia Pacific region that led to successful DTT operations initiated from intelligent planning, positively affecting field development decisions.

Introduction
With DTT, high-power pumps provide the ability to flow reservoir fluid at much higher rates than was possible with previous formation testers. Running such high-powered pumps for extended periods with wireline conveyances would dilute the mud system to the extent that the well overbalance could be jeopardized. DTTs, therefore, are conveyed on drillpipe and use a circulating sub, introduced to mix pumped hydrocarbons with circulated mud and to evacuate the mixture to surface continuously. The blowout preventer is kept closed, and the hydrocarbon/mud mixture returns to the surface through the choke line and is degassed in the mud/gas separator. Continuous circulation of mud during the flow period can cause thermally induced drillpipe shrinkage. To mitigate this development, a slipjoint is used to decouple drillpipe from the formation tester. Finally, the formation tester is equipped with high-resolution gauges that enable longer buildup times before the signal-to-noise limits are reached.

Real-Time Data Integration
A fast, automated, and intuitive solution has been developed to enable real-time data integration. 3D reservoir context is generated using automated dip-processing engines, together with well deviation and formation tops. During the planning phase, the process is initiated with offset data. As logs are acquired on the current well, automated workflows extract the dips from image data, and the 3D model is updated in a matter of hours. Logged properties can be propagated through the 3D model. The workflow is scalable to the data available.
This 3D reservoir model will be available during formation-testing operations, in which 2D gradient plots are connected to the 3D structural views. Faults and layer properties are added in 3D space to generate a spatial understanding of the data. The workflow resides in a cloud-based collaborative platform. This feature, combined with multiwell filters and visualization templates, makes generation of critical workflows to determine connectivity and fluid grading easier and more intuitive, enabling faster real-time decisions.