Lost Circulation Material Design for Highly Inclined Or Horizontal Well Sections

Abstract

The use of particulate lost circulation material (LCM) is common in treating lost circulation events of subterranean drilling. LCM isolates the wellbore pressure from fracture tip by forming an impermeable agglomerate inside the wellbore fractures. Fracture width estimation is the center piece of designing the particle size distribution (PSD) of LCM blends. State-of-the-art practice for width estimation of wellbore fractures has been predominantly associated with assumption of axial fracture development from wellbores. However, this assumption is not valid for all wellbore orientations. Shallow vertical wellbores and highly inclined or horizontal wellbores in a normal faulting regime are example configurations where axisymmetric wellbore fractures develop transverse to the wellbore axis. The change in fracture geometry yields a substantially different width estimate for transverse fractures compared to the axial ones. This study aims at demonstrating this disparity and the impact that it would have on the LCM blend design. For this purpose, a linear elastic fracture mechanics solution is applied to the fractured wellbore to estimate the fracture width. Results indicate that an axial model of the fracture could substantially overestimate the fracture width depending on the wellbore inclination and in-situ stress magnitudes. Application of the solution in selecting the composition of a three-component blend from selected LCMs via a blend particle size criterion is shown. The discrepancy between the LCM blends PSDs obtained from the axial and transverse models of the wellbore fracture are thoroughly discussed.