--> Abstract: Building a Fault Framework, Structural Modeling and Fracture Prediction in the Clair Field, UK, by Robert W. Krantz, Andrew Conway, and Andrew Cole; #90078 (2008)

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Building a Fault Framework, Structural Modeling and Fracture Prediction in the Clair Field, UK

Robert W. Krantz1, Andrew Conway2, and Andrew Cole2
1Subsurface Technology, ConocoPhillips, Houston, TX
2North Sea BU, ConocoPhillips (UK), Aberdeen, United Kingdom

Clair Field lies west of the Shetland Islands on the North Atlantic rifted margin. The main structure includes a series of fault blocks with complex, internal faulting. Oil production comes from Devonian sandstones with locally good matrix properties. However, well performance and both horizontal and vertical connectivity suggest that fractures contribute substantially to flow.

Predicting fracture distribution and effectiveness requires an integrated approach. In order to test this approach we analyzed a pilot area around the first production well. Our method first generates a high fidelity structural framework from the initial seismic interpretation. This framework contains faults that have complete splay and intersection geometries. The fault network then provides detailed offsets of mapped horizons with hanging wall and footwall cutoffs and throw distributions.

Elastic dislocation models based on the structural framework, combined with rock properties and boundary conditions, yield distributions of stress and strain parameters and predicted fractures. These agree very well with fractures interpreted from image logs in the production well. Applying the present day stress field discriminates fractures that more likely contribute to flow. The predicted stress-enhanced fractures cluster near the heel of the horizontal well, where PLT data suggests most flow enters the well bore.

The success of the methods used justifies further application over the entire production area.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas