2D Numerical Simulation of Improving Wellbore Stability in Shale Using Nanoparticles Based Drilling Fluid

The past decade has seen increased focus on nanoparticle (NP) based drilling fluid to promote wellbore stability in shales. With the plugging of NP into shale pores, the fluid pressure transmission can be retarded and wellbore stability can be improved. For better understanding of the interaction between shale and NP based drilling fluid based on previous pressure transmission tests (PTTs) on Atoka shale samples, this paper reports the numerical simulation findings of wellbore stability in the presence of NP based drilling fluid, using the 2D fluid-solid coupling model in FLAC3D™ software. The results of previous PTT are discussed first, where the steps of numerical simulation, the simulation on pore fluid pressure transmission, the distribution of stress and the deformation of surrounding rock are presented. The mechanisms of NP in reducing permeability and stabilizing shale are also discussed. Results showed that fluid filtrate from water-based drilling fluid had a strong tendency to invade the shale matrix and increase the likelihood of wellbore instability in shales. However, the pore fluid pressure near wellbore areas could be minimized by plugging silica NP into the nanoscale pores of shales, which is consistent with previous PTT. Pore pressure transmission boundaries could also be restricted with silica NP. Furthermore, the stress differential and shear stress of surrounding rock near the wellbore was reduced in the presence of NP. The plastic yield zone was minimized to improve wellbore stability. The plugging mechanism of NP may be attributed to the electrostatic and electrodynamic interactions between NP and shale surfaces that are governed by Derjaguin-Landau-Verwey-Overbeek (DLVO) forces, which allowed NP to approach shale surfaces and adhere to them. We also found that discretization of the simulation model was beneficial in distinguishing the yield zone distribution of the surrounding rock in shales. The combination of PTT and the 2D numerical simulation offers a better understanding of how NP-based drilling fluid can be developed to address wellbore stability issues in shales.

[1]  S. Ghanbari,et al.  Enhancing the physical plugging behavior of colloidal silica nanoparticles using binomial size distribution , 2016 .

[2]  Hehua Zhu,et al.  A nonlinear semi-concurrent multiscale method for fractures , 2016 .

[3]  Xiaoming Wu,et al.  Experimental study and stabilization mechanisms of silica nanoparticles based brine mud with high temperature resistance for horizontal shale gas wells , 2015 .

[4]  Jingnan Dong,et al.  A chemo-mechanical coupling model of deviated borehole stability in hard brittle shale , 2014 .

[5]  Timon Rabczuk,et al.  A coupled thermo-hydro-mechanical model of jointed hard rock for compressed air energy storage , 2014 .

[6]  S. Akhtarmanesh,et al.  Improvement of wellbore stability in shale using nanoparticles , 2013 .

[7]  A fluid-solid-chemistry coupling model for shale wellbore stability , 2012 .

[8]  Mukul M. Sharma,et al.  Decreasing Water Invasion Into Atoka Shale Using Nonmodified Silica Nanoparticles , 2012 .

[9]  Jie Cao,et al.  Shale inhibitive properties of polyether diamine in water-based drilling fluid , 2011 .

[10]  Russell T. Ewy,et al.  Wellbore-Stability Performance of Water-Based Mud Additives , 2009 .

[11]  Philip H. Nelson,et al.  Pore-throat sizes in sandstones, tight sandstones, and shales , 2009 .

[12]  Mengjiao Yu,et al.  Chemical–mechanical wellbore instability model for shales: accounting for solute diffusion , 2003 .

[13]  Gudmundur S. Bodvarsson,et al.  A modeling approach for analysis of coupled multiphase fluid flow, heat transfer, and deformation in fractured porous rock , 2002 .

[14]  M. Chenevert,et al.  Shale preservation and testing techniques for borehole-stability studies , 2001 .

[15]  Eric van Oort,et al.  Transport in shales and the design of improved water-based shale drilling fluids , 1996 .

[16]  Ronald P. Steiger,et al.  Quantitative determination of the mechanical properties of shales , 1992 .

[17]  Me Chenevert Me,et al.  Shale control with balanced- activity oil- continuous muds , 1970 .