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.