Print this pageA Revised Structural Model of the Papuan Fold Belt and Implications for Petroleum Prospectivity
BUCHANAN, PETER
Our structural understanding of the Papuan Fold Belt suffers from a lack of data which forces a reliance on conceptual models. Such models are necessarily derived from other fold belts, which in reality, may or may not be appropriate. A strong momentum developed throughout the Eighties to interpret all contractional belts in terms of thin-skin tectonics. As a result, large parts of the Papuan Fold Belt were consequently down graded with regards to prospectivity as folds were interpreted as detached above reservoir objectives. The lack of constraint on sub-surface geometry has led to several wells being drilled in non-optimal locations or being prematurely abandoned. Subsequent drilling however, has confirmed the hydrocarbon potential of some of these structures. There is now a need to move away from the application of over simplistic and purely geometrical models which have proven to be inadequate in explaining the structure encountered in wells. Recent advances in the understanding of fold belt evolution have refocussed attention on the type of structural style used in modelling the Papuan Fold Belt. The interpretation presented here considers the role of pre-contraction basin architecture and mechanical stratigraphy as controlling mechanisms in trap development. A revised 'thick-skin' structural model is advanced whereby buckle folding and basin inversion are fundamental end-member processes in the overall development of the fold belt. The model is consistent with seismic interpretations from the foreland, newly acquired seismic data from the fold belt,recent physical modelling results, surface data and structures observed in other analogue fold belts. Such a model has crucial implications to petroleum prospectivity, primarily in terms of structural definition but also in terms of source potential and reservoir distribution.