--> Use of Analogue Modeling for Hydrocarbon Exploration: An Example in Papua New Guinea Fold and Thrust Belt (Onshore).

2018 AAPG International Conference and Exhibition

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Use of Analogue Modeling for Hydrocarbon Exploration: An Example in Papua New Guinea Fold and Thrust Belt (Onshore).

Abstract

Seismic imaging in foreland fold and thrust belts remains a challenge as geometries of fold cores or of deep structures are often difficult to image due to structural complexity. This is the case in onshore Papua New Guinea, where the 1km thick karstified Darai Limestone, covered by dense jungle, plays against the structural interpreters. In this communication, we would like to present the results of the workflow used to handle the complexity of the Agogo and Kutubu structures in the Papua New Guinea Fold and Thrust belt. These anticlinal structures are en-echelon, NW-SE trending, and truncated by near-planar thrusts, with producing oil and gas fields in both their hangingwall and footwall. The two fold structures are 15 km apart along the strike of the fold belt, and although their overall structural form is similar, there are significant lateral variations in geometry that need to be understood in order to optimize field development. Understanding the 3D spatial link between Agogo and Kutubu and the evolution of the structures through time is crucial to minimize structural uncertainty during further field development. Surface data, more than70 wells (including 10 that penetrate the breakthrust) and poor quality 2D seismic data are available for the area. The shallower structures (down to ~3km) are relatively well-constrained by these data, but the deeper structures rely on interpretation combined with geometrical forward modelling and balanced cross sections. Multiple interpretations for the link between the two anticlines are possible. They include a breached compressional relay system, a lateral ramp, inversion of an extensional relay system, or inversion of a single extensional fault subsequently offset by right-lateral strike-slip. To test the structural interpretations and to understand what is the key parameter responsible for the lateral variation, a set of sandbox experiments have been performed inside a scanner device, which records the 3D deformation through time. The results have yielded key observations on the mechanical behavior of the system and allows to identify the parameters that impact the geometry of the structures through time (the rheology, the sequence of deformation, the rate of deformation, the brittle/ductile ratio) and that lead to lateral variations (basement shape, lateral thickness variation). This communication will show the results obtained with analogue models for the understanding of the Agogo-Kutubu field.