Wrench Fault in Hydrocarbons industry

A wrench fault, also known as strike-slip fault, is a type of fault where the movement of blocks is primarily horizontal and is parallel to the strike of the fault plane. These can be either :

• Right lateral (dextral) : Where the opposite side moves to the right.
• Left lateral (sinistral) : Where the opposite side moves to the left.

These faults often form in transform plate boundaries or in strike-slip tectonic regimes and can be associated with complex geological structures like flower structures or pull-apart basins.

Importance in the Hydrocarbon Industry

1. Trap formation :
   • Pull-Apart Basins : Wrench faults can create pull-apart basins where sedimentary sequences accumulate. These basins can act as hydrocarbon kitchens due to rapid burial and heat flow.
   • Releasing and Restraining Bends :
     • Releasing bends may form basins and traps.
     • Restraining bends can create uplift and anticlines that act as structural traps.
2. Migration Pathways :
   • Strike-slip faults can act as conuits for hydrocarbon migration.
   • Fractures and fault planes may provide permeable pathways for hydrocarbons to move from source rocks to reservoirs.
3. Compartmentalization :
   • Wrench faults can segment reservoirs into compartments, which may –
     • require multiple wells for full drainage.
     • Affect pressure regimes across the fault zones.
4. Reservoir Enhancement :
   • In some cases, faulting can incrase permeability through fracturing.
   • Enhanced secondary porosity due to movement and stress along the fault can improve reservoir quality.
5. Seismic Interpretation and Risk :
   • Wrench fault systems often have complex subsurface geometries, making them challenging but rewarding exploraiton targets.
   • Understanding their orientation and offsert is key in 3D seismic interpretation and well planning.

Examples of Wrench fault related Plays

• San Andreas Fault (USA)
• North Sea
• Dead Sea Transform Fault