Anisotropic Wellbore Stability Model For Naturally Fractured and Foliated Formations with Multi-Weakness Plane Failure

2015 ◽  
Author(s):  
Qi Li ◽  
Adam Yousefzadeh ◽  
Roberto Aguilera
Keyword(s):  
Wellbore Stability ◽  
Plane Failure ◽  
Stability Model ◽  
Naturally Fractured

Managing Wellbore Stability Window and Well Integrity by Adjusting the Tight Margin to Successfully Drill through Naturally Fractured Zone Onshore Niger Delta

2021 ◽  
Author(s):  
Bassey Akong ◽  
Samuel Orimoloye ◽  
Friday Otutu ◽  
Akinwale Ojo ◽  
Goodluck Mfonnom ◽  
...  
Keyword(s):  
Niger Delta ◽  
Wellbore Stability ◽  
Rock Properties ◽  
Failure Behavior ◽  
Natural Fractures ◽  
Gas Well ◽  
Well Integrity ◽  
Trajectory Formation ◽  
Naturally Fractured ◽  
Drilling Operations

Abstract The analysis of wellbore stability in gas wells is vital for effective drilling operations, especially in Brown fields and for modern drilling technologies. Tensile failure mode of Wellbore stability problems usually occur when drilling through hydrocarbon formations such as shale, unconsolidated sandstone, sand units, natural fractured formations and HPHT formations with narrow safety mud window. These problems can significantly affect drilling time, costs and the whole drilling operations. In the case of the candidate onshore gas well Niger Delta, there was severe lost circulation events and gas cut mud while drilling. However, there was need for a consistent adjustment of the tight drilling margin, flow, and mud rheology to allow for effective filter-cake formation around the penetrated natural fractures and traversed depleted intervals without jeopardizing the well integrity. Several assumptions were validly made for formations with voids or natural fractures, because the presence of these geological features influenced rock anisotropic properties, wellbore stress concentration and failure behavior with end point of partial – to-total loss circulation events. This was a complicated phenomenon, because the pre-drilled stress distribution simulation around the candidate wellbore was investigated to be affected by factors such as rock properties, far-field principal stresses, wellbore trajectory, formation pore pressure, reservoir and drilling fluids properties and time without much interest on traversing through voids or naturally fractured layers. This study reviews the major causes of the severe losses encountered, the adopted fractured permeability mid-line mudweight window mitigation process, stress caging strategies and other operational decisions adopted to further salvage and drill through the naturally fractured and depleted intervals, hence regaining the well integrity by reducing NPT and promoting well-early-time-production for the onshore gas well Niger Delta.

A wellbore stability model for hydrate bearing sediments

2007 ◽  
Vol 57 (1-2) ◽  
pp. 209-220 ◽  
Author(s):  
Reem Freij-Ayoub ◽  
Chee Tan ◽  
Ben Clennell ◽  
Bahman Tohidi ◽  
Jinhai Yang
Keyword(s):  
Wellbore Stability ◽  
Stability Model ◽  
Hydrate Bearing Sediments
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