scholarly journals Chemical and Thermal Effects on Wellbore Stability of Shale Formations

2001 ◽  
Author(s):  
M. Yu ◽  
G. Chen ◽  
M.E. Chenevert ◽  
M.M. Sharma
Keyword(s):  
Thermal Effects ◽  
Wellbore Stability ◽  
Shale Formations

An Experimental Study to Demonstrate that Nanoparticles can Filter into Shale Formations and Improve Wellbore Stability

2020 ◽  
Author(s):  
Nancy Zhou ◽  
Yongkang Wu ◽  
Meng Lu ◽  
Yucheng Li ◽  
Fuchen Liu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Wellbore Stability ◽  
Shale Formations

Wellbore Stability in Layered Rocks: A Comparative Study of Strength Criteria

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Xiangchao Shi ◽  
Xiao Zhuo ◽  
Yue Xiao ◽  
Boyun Guo ◽  
Cheng Zhu ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Good Choice ◽  
Wellbore Stability ◽  
Gas Field ◽  
Well Drilling ◽  
Shale Formations ◽  
Single Plane ◽  
Collapse Pressure ◽  
Bedding Planes ◽  
Laminated Structures

Abstract Wellbore instability is a critical issue restricting efficient well drilling and successful development of oil and gas field. Most instability problems originate from shale formations because of their distinct laminated structures that cause significant anisotropy and moderate to high clay contents that are prone to shrinkage and swelling. To account for these influences on the mechanical responses of shales, this study aims to identify an appropriate strength criterion for stability analyses. Two anisotropic criteria including single plane of weakness and the modified Hoek–Brown criteria were compared to evaluate their suitability in characterizing the anisotropic strength of layered rocks including shale, schist, and slate under different confining pressures. Comparative case studies indicated that the single plane of weakness criterion overestimates the strength of layered rocks at some orientation angles. The modified Hoek–Brown criterion can fit well with the experimental data of layered rocks. Moreover, wellbore stability analysis models for shale gas wells were built, respectively, for each criterion and applied to in situ scenarios. The single plane of weakness and modified Hoek–Brown criteria provide similar results of collapse pressure, and the shale failure is mainly determined by the bedding plane. This further validates that the modified Hoek–Brown criterion is a good choice for wellbore stability analysis in shale formations with bedding planes. This study shows the potential of using the modified Hoek–Brown criterion to enhance the safety and efficiency of well drilling and operation in shale formations.

scholarly journals Coupled THM Modelling of Wellbore Stability with Drilling Unloading, Fluid Flow, and Thermal Effects Considered

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Shanpo Jia ◽  
Caoxuan Wen ◽  
Fucheng Deng ◽  
Chuanliang Yan ◽  
Zhiqiang Xiao
Keyword(s):  
Fluid Flow ◽  
Pore Pressure ◽  
Thermal Effects ◽  
Process Analysis ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Deep Well ◽  
Underbalanced Drilling ◽  
The Stability ◽  
Pressure Stress

Both overbalanced drilling and underbalanced drilling will lead to the change of pore pressure around wellbore. Existing research is generally based on hydraulic-mechanical (HM) coupling and assumes that pore pressure near the wellbore is initial formation pressure, which has great limitations. According to the coupled theory of mixtures for rock medium, a coupled thermal-hydraulic-mechanical (THM) model is proposed and derived, which is coded with MATLAB language and ABAQUS software as the solver. Then the wellbore stability is simulated with the proposed model by considering the drilling unloading, fluid flow, and thermal effects between the borehole and the formation. The effect of field coupling on pore pressure, stress redistribution, and temperature around a wellbore has been analyzed in detail. Through the study of wellbore stability in different conditions, it is found that (1) for overbalanced drilling, borehole with impermeable wall is more stable than that of ones with permeable wall and its stability can be improved by reducing the permeable ability of the wellbore wall; (2) for underbalanced drilling, the stability condition of permeable wellbore is much higher than that of impermeable wellbore; (3) the temperature has important influence on wellbore stability due to the variation of pore pressure and thermal stress; the wellbore stability can be improved with cooling drilling fluid for deep well. The present method can provide references for coupled thermal-hydraulic-mechanical-chemical (THMC) process analysis for wellbore.

Investigating the Relation Between Sorption Tendency and Hydraulic Properties of Shale Formations

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Vahid Dokhani ◽  
Mengjiao Yu ◽  
Chao Gao ◽  
James Bloys
Keyword(s):  
Pore Pressure ◽  
Adsorption Isotherms ◽  
Hydraulic Properties ◽  
Transport Coefficients ◽  
Exchange Capacity ◽  
Wellbore Stability ◽  
Experimental Results ◽  
Shale Formations ◽  
Hydraulic Diffusivity ◽  
Rock Types

Routine measurement of hydraulic diffusivity of ultralow permeability rocks, such as shale, is a prolonged process. This study explores the effects of a sorptive characteristic of the porous medium on hydraulic diffusivities of shale rocks. The examined rock types include Mancos Shale, Catoosa Shale, Eagle Ford Shale, and core samples from the Gulf of Mexico. First, the adsorption isotherms of the selected shale rocks were obtained. Then, the hydraulic properties of the selected shale rocks were determined using Shale/Fluid Interaction Testing Cell, which employs pore pressure transmission technique. The experimental results show that the moisture content of shale is correlated with water activity using a multilayer adsorption theory. It is found that the adsorption isotherms of various shale formations can be scaled using their respective cation exchange capacity (CEC) into a single adsorption curve. Analyzing the transient pore pressure response in the downstream side of shale sample allows calculating the transport coefficients of shale samples. Hydraulic properties of shales are obtained by matching the pore pressure history with one-dimensional coupled fluid flow model. The experimental results indicate that sorptive properties can be inversely related to the hydraulic diffusivity of shale rocks. It is found that with an increase in the magnitude of sorption potential of shale, the hydraulic diffusivity decreases. This study is useful for shale characterization and provides a correlation, which can have various applications including, but not limited to, wellbore stability prediction during well planning.

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