Abstract

Suban field in southern Sumatra, Indonesia, is a fractured carbonate/crystalline wet-gas reservoir in a tectonically active island-arc setting. Reservoir-scale right-oblique reverse faults and folds that have trapped the hydrocarbons have been related previously to deformation in the back-arc setting of Sumatra associated with oblique subduction of the Indo-Australian Plate at the Sunda trench. Increased well productivity in some parts of the field was inferred to correlate with completing wells in the damage zones of critically stressed faults. Satellite interferometry acquired in 2008 through 2011 involving specially stacked and filtered interferograms, following prior applications to heavy-oil fields and Arctic sea ice, reveals active deformation in Suban field. Several areas of localized subsidence potentially exceeding ∼5 mm/yr have been identified in the field. Horizontal movements of comparable magnitude were resolved above the major right-oblique, critically stressed fault zone in the southwestern part of the field, corroborating wellbore-based inferences from the reservoir. Block-tectonic models constrained by GPS measurements across the entire Sumatra contractional orogen predict comparable magnitudes and directions for horizontal motions observed locally at Suban. The combination of InSAR and GPS-based plate-tectonic models provides a robust tool for monitoring the deformation of oil and gas fields in tectonically active areas.

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