Bryan DeVault¹
(1) Nederlandse Aardolie Maatschappij (NAM), 9400 HH Assen, Netherlands

Abstract: Analysis of fault reactivation and paleo-juxtaposition relationships in the West Netherlands Basin

Laramide inversion in the West Netherlands Basin significantly altered the configuration of traps formed by late Jurassic rifting in the basin. By selectively uplifting sediments, often along pre-existing normal faults, inversion extensively altered pre-existing lateral juxtaposition relationships. Reconstruction of fault movement history on several dry structures which have favorable present-day juxtaposition revealed unfavorable lateral juxtaposition during the time the structures were being charged.

In the most heavily inverted portion of the basin, however, inversion and subsequent erosion were so extreme that all of the major faults have been eroded to below their null points, complicating reconstruction of fault movement histories. To correctly evaluate lateral seal risk for prospects in this area, techniques were developed to estimate the probability and amount of boundary-fault reactivation where the overlying section was eroded and only the underlying rift topography is preserved. These methods are (1) investigation of along-fault differential uplift by use of seismic interval velocities, (2) statistical analysis of Laramide fault reactivation trends in areas of the basin where a more complete section is preserved, and (3) comparison of structural styles seen elsewhere in the basin with styles seen in the area being evaluated. Applying these methods to a horst block under study revealed a significant chance of past unfavorable lateral juxtaposition that had not been recognized as a risk in previous studies.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana