Advanced mud gas service finds hidden pay zones in brownfield

Algeria, Africa, Onshore

An operator in Algeria used FlairFlex™ advanced real-time fluid logging and analysis service to derisk formation evaluation and identify bypassed pay zones in a challenging brownfield asset.

To optimize well productivity in mature fields, operators generally log the wells using standard openhole logging tools and calculate hydrocarbon volume using formation pressure measurements. However, even advanced logs can be misleading in brownfield developments, such as the Triassic Argilo-Greseux Inferieur (TAGI) Formation in Algeria’s Berkine Basin, due to heterogeneity and pressure depletion. Both of these factors can increase uncertainty during gradient interpretation and petrophysical analysis, raising the risk of incorrect fluid typing. This operator needed to identify recoverable hydrocarbons and classify the brownfield’s remaining fluids—as quickly and accurately as possible.

Log identifying hydrocarbons in the TAGI U3, TAGI U1, TAGI M1, and TAGI L3 formations.
SLB integrated data from the FlairFlex service with openhole log data to classify formation fluids and confirm the presence of hydrocarbons in the TAGI U3, TAGI U1, TAGI M1, and TAGI L3 formations.

To accelerate decision making and derisk formation evaluation, SLB recommended a unified workflow that combined advanced quantitative mud gas analysis with basic openhole log data. FlairFlex fluid logging and analysis service gathered formation data during drilling, providing early insights into C1–C5 reservoir fluid properties and composition through real-time quantification. SLB data scientists used machine-learning algorithms within the Techlog™ wellbore software platform to analyze data from the FlairFlex service—predicting pay zones, fluid contacts, swept zones, fluid properties, and gas/oil ratio within minutes. This analysis identified wet gas, gas condensate, oil, and water—revealing much more reservoir complexity and providing deeper insights than standard formation evaluation techniques based on regional gradient analysis. The operator used the data acquired from the FlairFlex service to optimize subsequent wireline logging, formation testing, and fluid scanning operations.

SLB used the FlairFlex service to calculate total hydrocarbon contribution, providing a qualitative indication of reservoir hydrocarbon saturation. Zones of interest were confirmed with advanced downhole fluid analysis stations over the formation’s top, middle, and lower sandstone layers. Using this integrated workflow, the operator discovered moveable oil within previously swept zones and identified a high-potential oil zone that had been classified as a water zone based on the initial evaluation.

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