Tezislər / Theses

References 
1. [Adamson, K., Birch, G., Macdonald, C., Mack, D., & Quadri, A. (1998). High-Pressure, 
High-Temperature Well Construction.] 
2. [Alderman, N.J., Gavignet, A., Guillot, D., & Maitland, G.C. (1988). High-Temperature, 
High- Pressure Rheology of Water-Based Muds] 
3. [Drilling Fluid and Materials] 
4. [Drilling Fluid Selection and Formulation] 
5. [Thaemlitz, C.J., Patel, A.D., Conn, L. (1999). New Environmentally Safe High-
Temperature Water-Based Drilling-Fluid System. SPE Drilling & Completion, 14(3),
185-189] 

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THE 3
rd
 INTERNATIONAL SCIENTIFIC CONFERENCES OF STUDENTS AND YOUNG RESEARCHERS 
dedicated to the 99
th
anniversary of the National Leader of Azerbaijan Heydar Aliyev
77
THEORIES AND MODELS USED IN PROVIDING
WELLBORE STABILITY
Tural Guluzadeh
Azerbaijan State Oil and Industry University 
Baku, Azerbaijan 
 [e-mail] 
Supervisor: Ass.Prof. Rafig Ibrahimov 
Keywords: 
cation exchange capacity, filtration, diffusion, hydration osmosis, chemical 
activity 
It is necessary to assume the effect of shale and drilling mud interaction 
in wellbore stability analysis of shale to define the appropriate drilling mud 
density window due to decrease borehole instability and related issues in 
shale sections. Ensuring the stability of the well wall is possible only in finding 
solutions to the issue of predicting the deformation of the rocks and 
preventing the occurrence of deformation. When drilling deep and very deep 
wells, researchers and technologists do not have the opportunity to directly 
determine the deformation process. In this case, the theoretical and analytical 
approach to solving the problem of stability allows us to explain the nature of 
the formation of deformation in the rocks around the wellbore wall. Thus, it 
helps to find ways to forecasting them at the design stage and prevent them 
during drilling. 
Wellbore instability studies can be divided into three approaches. The 
first approach is the laboratory trial and error approach. This approach 
consists of formulating various drilling fluids based on shale-drilling fluid 
interaction and shale classification schemes. The second approach is purely 
mechanical and focuses on the pressures and stresses forced on the 
wellbore walls and the competence of the wellbore to resist these effects. 
The third approach, a relatively new approach, is the development of several 
quick tests used at the rig site to evaluate the shale cuttings while the well is 
being drilled. All three approaches have their merits and limitations.
First approach. Several researchers have attempted to solve shale 
problems using shale classification schemes. The classification schemes 
were based on several parameters such as their primary clay contents (from 
X-ray analysis), cation exchange capacity (from methylene blue test), relative 
hardness, degree of fracture, their relative tendencies to swell, and disperse, 
surface area, and shale dielectric constants. 
Kelly in particular classified shales based on hardness, clay minerals 
content, and degree of fractures. He used his results to present guidelines 
for choosing drilling fluids to combat troublesome shales [7,8]. 

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