Advanced Wellbore Stability Analysis for Drilling Naturally Fractured Rocks

2019 ◽  
Author(s):  
Yanhui Han ◽  
Chao Liu ◽  
Dung Phan ◽  
Khalid AlRuwaili ◽  
Younane Abousleiman
Keyword(s):  
Stability Analysis ◽  
Fractured Rocks ◽  
Wellbore Stability ◽  
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.

Wellbore Geomechanics of Extended Drilling Margin and Engineered Lost-Circulation Solutions

SPE Journal ◽  
2017 ◽  
Vol 22 (04) ◽  
pp. 1178-1188 ◽  
Author(s):  
Amin Mehrabian ◽  
Younane Abousleiman
Keyword(s):  
Mechanical Properties ◽  
Stability Analysis ◽  
Analytical Approach ◽  
Wellbore Stability ◽  
Tensile Failure ◽  
Mechanical Interaction ◽  
Lost Circulation ◽  
Drilling Operations ◽  
Secondary Fractures ◽  
Lost Circulation Materials

Summary Wellbore tensile failure is a known consequence of drilling with excessive mud weight, which can cause costly events of lost circulation. Despite the successful use of lost-circulation materials (LCMs) in treating lost-circulation events of the drilling operations, extensions of wellbore-stability models to the case of a fractured and LCM-treated wellbore have not been published. This paper presents an extension of the conventional wellbore-stability analysis to such circumstances. The proposed wellbore geomechanics solution revisits the criteria for breakdown of a fractured wellbore to identify an extended margin for the equivalent circulation density (ECD) of drilling. An analytical approach is taken to solve for the related multiscale and nonlinear problem of the three-way mechanical interaction between the wellbore, fracture wings, and LCM aggregate. The criteria for unstable propagation of existing near-wellbore fractures, together with those for initiating secondary fractures from the wellbore, are obtained. Results suggest that, in many circumstances, the occurrence of both incidents can be prevented, if the LCM blend is properly engineered to recover certain depositional and mechanical properties at downhole conditions. Under such optimal design conditions, the maximum ECD to which the breakdown limit of a permeable formation could be enhanced is predicted.

3-D Geomechanical Modeling and Wellbore Stability Analysis in Abu Butabul Field

2012 ◽  
Author(s):  
Qiuguo Li ◽  
Xing Zhang ◽  
Khalid Salim Al-Ghammari ◽  
Labib Mohsin
Keyword(s):  
Stability Analysis ◽  
Wellbore Stability

APPLICATION OF GUIDELINE CHARTS IN DECISIONMAKING ON WELL TRAJECTORY AND MUD WEIGHT PROGRAM

2001 ◽  
Vol 41 (1) ◽  
pp. 609
Author(s):  
X. Chen ◽  
C.P. Tan ◽  
C.M. Haberfield
Keyword(s):  
Stability Analysis ◽  
Case Studies ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Material Strength ◽  
Stress Regime ◽  
Wellbore Instability ◽  
Well Trajectory

To prevent or minimise wellbore instability problems, it is critical to determine the optimum wellbore profile and to design an appropriate mud weight program based on wellbore stability analysis. It is a complex and iterative decisionmaking procedure since various factors, such as in-situ stress regime, material strength and poroelastic properties, strength and poroelastic anisotropies, initial and induced pore pressures, must be considered in the assessment and determination.This paper describes the methodology and procedure for determination of optimum wellbore profile and mud weight program based on rock mechanics consideration. The methodology is presented in the form of guideline charts and the procedure of applying the methodology is described. The application of the methodology and procedure is demonstrated through two field case studies with different in-situ stress regimes in Australia and Indonesia.

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