Poromechanics Modeling of Wellbore Stability in Naturally Fractured Formations

2004 ◽  
Author(s):  
V. Nguyen ◽  
Y. Abousleiman ◽  
F.K. Mody
Keyword(s):  
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.

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

Optimize Internal Phase Salinity to Improve Wellbore Stability and Mitigate Lost Circulation

2021 ◽  
Author(s):  
Jianguo Zhang ◽  
Alan Rodgerson ◽  
Stephen Edwards
Keyword(s):  
Water Activity ◽  
Wellbore Stability ◽  
Chemical Effect ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Main Challenge ◽  
Internal Phase ◽  
Naturally Fractured ◽  
Drilling Operations ◽  
Shale Formation

Abstract Wellbore instability and lost circulation are two major sources of non-productive time (NPT) in drilling operations worldwide. Non-aqueous fluid (NAF) is often chosen to mitigate this and minimize the chemical effect on wellbore instability in reactive shales. However, it may inadvertently increase the risk of losses. A simple method to optimize internal phase salinity (IPS) of NAF is presented to improve wellbore stability and mitigate the increased possibility of losses. Field cases are used to demonstrate the effects of salinity on wellbore instability and losses, and the application of the proposed method. IPS is optimized by managing bidirectional water movement between the NAF and shale formation via semi-permeable membrane. Typically, higher shale dehydration is designed for shallow reactive shale formation with high water content. Whereas, low or no dehydration is desired for deep naturally fractured or faulted formation by balancing osmotic pressure with hydrostatic pressure difference between mud pressure and pore pressure. The simple approach to managing this is as follows: The water activity profile for the shale formation (aw,shale) is developed based on geomechanical and geothermal information The water activity of drilling fluid (aw,mud) is defined through considering IPS and thermal effects The IPS of NAF is manipulated to manage whether shale dehydration is a requirement or should be avoided If the main challenge is wellbore instability in a chemically reactive shale, then the IPS should be higher than the equivalent salinity of shale formation (or aw,shale > aw, mud) If the main challenge is losses into non-reactive, competent but naturally fractured or faulted shale, then IPS should be at near balance with the formation equivalent salinity (or aw, shale ≈ aw, mud) It is important that salt (e.g. calcium chloride – CaCl2) addition during drilling operations is done judiciously. The real time monitoring of salinity variations, CaCl2 addition, water evaporation, electric stability (ES), cuttings/cavings etc. will help determine if extra salt is required. The myth of the negative effects of IPS on wellbore instability and lost circulation is dispelled by analyzing the field data. The traditional Chinese philosophy: "following Nature is the only criteria to judge if something is right" can be applied in this instance of IPS optimization. A simple and intuitive method to manage IPS is proposed to improve drilling performance.

The Effect Of Wellbore Stability In Naturally Fractured Reservoirs

2015 ◽  
Author(s):  
Paul Fekete ◽  
Lopez A. Bruno ◽  
Adewale Dosunmu ◽  
Samuel Odagme ◽  
Adewale Sanusi ◽  
...  
Keyword(s):  
Fractured Reservoirs ◽  
Wellbore Stability ◽  
Naturally Fractured Reservoirs ◽  
Naturally Fractured

Convection and Dispersion in a Naturally Fractured Reservoir

2004 ◽  
Vol 7 (4) ◽  
pp. 303-316 ◽  
Author(s):  
E. Luna ◽  
A. Medina ◽  
C. Perez-Rosales ◽  
C. Trevino
Keyword(s):  
Fractured Reservoir ◽  
Naturally Fractured Reservoir ◽  
Naturally Fractured
Sign in / Sign up

Export Citation Format

Share Document