Abstract:

Reservoir reformation and petroleum distributions in Ordovician carbonate reservoirs are affected by strike-slip faults with northeast direction in the Northern Slope of Tazhong area. Large scale strike-slip faults always show north-east strike direction. Unfortunately, the horizontal displacement is too shorter to be identified by using poor quality and low resolution seismic data. Strike-slip faults show ubiquitous pullapart areas along the strike direction, because they have been affected by the tensional stress with northwest direction. And pull-apart areas are developed along the direction of strike-slip faults mainly affected by the formation of local stresses. The width and height of these areas are easy to be identified in 3D seismic data. A method is then proposed for displacement calculation by using the width and height of the pull-apart area to replace the horizontal displacement and vertical displacement of fault. Displacement calculation results by this method show a high agreement to geology regularity of strike-slip faults development. Large displacement in strike-slip faults always means a high activity regional area, and also shows a profitability area for reservoir reformation or petroleum accumulation.

Key words: the Northern Slope of Tazhong area, strike-slip fault, displacement, pull-apart area, petroleumdistribution