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Wellbore Stability - The PSI Software: SINTEF Petroleum Research

The PSI software analyzes wellbore stability by combining input parameters like formation conditions, properties, and wellbore data. It estimates failure probability inside the borehole wall over time. The model considers properties affecting stability, like stresses, pore pressure, temperature, mud chemistry, well geometry, rock strength, and elasticity. It outputs stability charts and maps showing safe and unstable zones versus time. The required inputs are formation conditions, wellbore data, and rock properties that can come from measurements, models, and literature when direct data is unavailable.

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152 views2 pages

Wellbore Stability - The PSI Software: SINTEF Petroleum Research

The PSI software analyzes wellbore stability by combining input parameters like formation conditions, properties, and wellbore data. It estimates failure probability inside the borehole wall over time. The model considers properties affecting stability, like stresses, pore pressure, temperature, mud chemistry, well geometry, rock strength, and elasticity. It outputs stability charts and maps showing safe and unstable zones versus time. The required inputs are formation conditions, wellbore data, and rock properties that can come from measurements, models, and literature when direct data is unavailable.

Uploaded by

NagaLangit69
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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SINTEF Petroleum Research

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Wellbore Stability – the PSI software
The wellbore stability model implemented in the PSI software combines input
parameters describing formation conditions, formation properties and wellbore data to
predict the stability of the well over time.

PSI estimates the probability for mechanical


failure inside the borehole wall; since the
model is largely analytical, solutions are
obtained very quickly. The software allows
for analysis of stresses and pore pressure
around the considered well and analysis of
stability versus time since drilling.

PSI software window showing at left the


input drop-down menus and at right, the
mud weight window output.

Features incorporated into PSI


The PSI model takes into account a rich amount Wellbore stability depends to various degrees
of rock and fluid properties affecting wellbore on all these above parameters, but some input
stability over time. Some general features it parameters are more important than others. To
can handle are anisotropic formation stresses, run PSI, the user should use all possible sources
arbitrary well orientation and various types for input parameters, such as:
of drilling mud (OBM/WBM/SOBM). More
specifically, the model takes into account: • direct measurements when available
• indirect measurements combined with suitable
• mud chemistry – osmosis and ionic exchange models/correlations
with clay platelets in rock • common accepted general knowledge
• well inclination & azimuth together with suitable models/correlations
• strength anisotropy • extract more information from small sample
• plasticity tests (as available from SINTEF) where
• temperature material cores are scarce

As a rule, the data should be as consistent as


The input parameters needed to run a possible, and one should use the same basic
models / physical understanding when extracting
wellbore stability prediction are: the different parameters. Some available
Formation conditions SINTEF tools and softwares can be used, such
– in situ stresses, pore pressure, temperature. as PRESSIM for initial pore pressure calculation,
Wellbore data FEM for depleted shale pore pressure, and
– well inclination & azimuth, borehole diameter, SINTEF models and correlations generating the
physical & chemical properties of the drilling needed input from other available parameters.
mud, mud temperature.
Formation properties
– mineralogy, porosity, strength parameters,
elastic parameters, plastic parameters, thermo-
elastic parameters, poro-elastic parameters, Contact persons:
October Erling Fjær
chemo-elastic parameters, diffusion constants.
2007 E-mail: erling.fjar@sintef.no
Phone: +47 73 59 11 89

www.sintef.com
PSI output:
mud weight window
evolution with time.

PSI output:
stability chart showing borehole
cross section with in situ
stress directions and extent of
breakouts on perimeter of well
where wall is unstable.

PSI output:
stress map inside formation
showing appearance of shear
failure at borehole wall.

s
SINTEF Petroleumsforskning AS
SINTEF Petroleum Research

Main Office: Bergen Office Stavanger Office Houston Office


Postal address: NO-7465 Trondheim, Norway Visiting address: Høyteknologisenteret Visiting address: Rogaland Kunnskapspark Visiting address: 11999 Katy Freeway,
Visiting address: S.P. Andersens vei 15B Thormøhlensgt. 55, 5008 Bergen Prof. Olav Hanssens vei 7A, 4068 Stavanger Suite 490, Houston TX 77079, USA
Phone: +47 73 59 11 00 Phone: +47 55 54 39 00 Phone: +47 51 87 44 00 Phone:281-854-2589 (extension #214)
Fax: +47 73 59 11 02 Fax: +47 55 54 39 05 Fax: +47 51 87 44 01 Fax: 281-854-2588
E-mail: info@iku.sintef.no

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