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
tural.quluzadeh@gmail.com
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].