Finite-Element Analysis of Deliberately Increasing the Wellbore Fracture Gradient
Lost circulation caused by low fracture gradients is the cause of many drilling related problems. When lost circulation occurs, standard practice is to add lost circulation materials to stop mud from flowing into formations. To improve the treatment for lost circulation caused by low fracture gradients, special designed materials are added to the mud to seal the induced fractures around the wellbore. This operation is in the literature referred to as wellbore strengthening. The size, type and geometry of sealing materials used in this process are the object of debate depending on the specific technique applied. Further, the physical mechanism of these techniques, in various rock permeabilities, is not fully understood. The main objective for this study was to build a finite-element model for fracture growth, and a parametric study was conducted to determine the permeability effect on fracture growth and geometry. The results show that fracture growth is a strong function of material permeability therefore in highly permeable rocks, cracks widen more than they do in less permeable rocks. The simulation results formed the basis of a fracture geometry model that permits prediction of the fracture geometry formed around the wellbore. The simulations also demonstrated that to enhance the sealing mechanism the fracture geometry formed in the formations is a contributing factor.
S. H. Salehi and R. Nygaard, "Finite-Element Analysis of Deliberately Increasing the Wellbore Fracture Gradient," Proceedings of the 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium (2010, Salt Lake City, UT), American Rock Mechanics Association (ARMA), Jun 2010.
44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium (2010: Jun. 27-30, Salt Lake City, UT)
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Contributing Factor; Finite Element Analysis; Finite-Element Models; Fracture Geometries; Fracture Gradient; Fracture Growth; Lost Circulation Materials; Parametric Study; Permeability Effects; Permeable Rocks; Physical Mechanism; Sealing Material; Simulation Result; Standard Practices; Wellbore, Computational Geometry; Computer Simulation; Finite Element Method; Oil Field Equipment; Rock Mechanics
Article - Conference proceedings
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01 Jun 2010