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Wellbore stability analysis and application to optimize high-angle wells design in Rumaila oil field, Iraq

  • Hussein Saeed AlmalikeeEmail author
  • Fahad M. Al-Najm
Original Article
  • 9 Downloads

Abstract

Mechanical wellbore instability is one of the main issues during the drilling operations, this problem causes around 14% of drilling nonproductive time (NPT) for new wells in Rumaila oil field; these breakouts were commonly observed in the shale and weak shaly sandstones along Rumaila geological column. In this study, a quantitative wellbore failure analysis was carried out through applying modified Lade criteria on five wells in Rumaila oil field (A, B, C, E and F). The results gave a prediction of the appropriate mud density that can control the wellbore shear failure for any well type in order to eliminate or minimize wellbore instability and indicated that the preferred direction to drill deviated and horizontal wells should be parallel to maximum horizontal stress (NE–SW). The study also introduced the recommended drilling mud weight for vertical and deviated wells in Rumaila oil field for the sake of gaining wellbore stability which requires raising the drilling mud weight to more than 1.27 gm/cm3 starting from bottom of Sadi Formation to the well total depth. The results also showed that wells with low inclination (less than 30°) are less stable than highly inclination wells (more than 30°).

Keywords

Wellbore stability Horizontal stress Rumaila oil field 

List of symbols

\(\sigma_{X} , \sigma_{Y} , \sigma_{Z}\)

Normal stresses in any Cartesian coordinate system, psi

\(\sigma_{x} ,\sigma_{y} , \sigma_{z}\)

In situ normal stresses in wellbore coordinate system, psi

\(\sigma_{zz}\)

The stress acting in the direction of the wellbore, psi

\(\tau_{{\theta^{z} }}\)

Shear stresses at wall of wellbore, psi

\(\tau_{XY} ,\tau_{YZ} , \tau_{ZX}\)

Shear stresses in any Cartesian coordinate system, psi

\(\tau_{xy} , \tau_{yz} , \tau_{zx}\)

In situ shear stresses in wellbore coordinate system, psi

m

Parameter of material, dimensionless

P0

Pore pressure, psi

Pa

Atmospheric pressure, psi

pa

Atmospheric pressure, psi

v

Poisson’s ratio, unitless

η1

A parameter of material linked with friction, dimensionless

θ

The angle measured clockwise from maximum horizontal stress direction, degrees

Notes

References

  1. Aadnoy BS (2010) Modern well design. CRC Press, LondonCrossRefGoogle Scholar
  2. Al-Ajmi AM, Zimmerman RW (2009) A new well path optimization model for increased mechanical borehole stability. J Petrol Sci Eng 69(1):53–62CrossRefGoogle Scholar
  3. Al-Bazali T, Zhang J, Chenevert ME, Sharma MM (2007) Factors controlling the compressive strength and acoustic properties of shales when interacting with water-based fluids. Int J Rock Mech Min Sci 45(5):729–738CrossRefGoogle Scholar
  4. Aslannejad M, Khaksar Manshad A, Jalalifar H (2013) Analysis of vertical, horizontal and deviated wellbores stability. Am J Oil Chem Technol 1(8):2326–6570Google Scholar
  5. Burgess T (1991) Horizontal drilling comes of age. Oil Field Rev 2(3):22–23Google Scholar
  6. Ewy RT (1999) Wellbore-stability predictions by use of a modified Lade criterion. SPE Drill Compl 14(02):85–91CrossRefGoogle Scholar
  7. Fjaer E, Holt RM, Raaen AM, Risnes R, Horsrud P (2008) Petroleum related rock mechanics, vol 53. Elsevier, New YorkGoogle Scholar
  8. Lade PV (1977) Elasto-plastic stress-strain theory for cohesionless soil with curved yield surfaces. Int J Solids Struct 13(11):1019–1035CrossRefGoogle Scholar
  9. Manshad AK, Jalalifar H, Aslannejad M (2014) Analysis of vertical, horizontal and deviated wellbores stability by analytical and numerical methods. J Pet Explor Prod Technol 4(4):359–369CrossRefGoogle Scholar
  10. Mitchell RF, Miska SZ (2011) Fundamentals of drilling engineering; society of petroleum engineers. Society of Petroleum Engineers, RichardsonGoogle Scholar
  11. Osisanya SO (2012) Practical approach to solving wellbore instability problems. SPE Distinguished Lecture series, Port HarcourtGoogle Scholar
  12. Rabia H (2002) Well engineering and construction. Entrac Consulting LimitedGoogle Scholar
  13. Rahimi R (2014) The effect of using different rock failure criteria in wellbore stability analysis. Missouri University of Science and TechnologyGoogle Scholar
  14. Yi X, Ong S, Russell JE (2006) Quantifying the effect of rock strength criteria on minimum drilling mud weight prediction using polyaxial rock strength test data. Int J Geomech 6(4):260–268CrossRefGoogle Scholar
  15. Zhou S, Hillis R, Sandiford M (1994) A study of the design of inclined wellbores with regard to both mechanical stability and fracture intersection, and its application to the Australian North West Shelf. J Appl Geophys 32(4):293–304CrossRefGoogle Scholar
  16. Zoback MD (2007) Reservoir geomechanics. Cambridge University Press, CambridgeCrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Basrah Oil Company, Ministry of OilBasrahIraq
  2. 2.Department of Geology, College of ScienceUniversity of BasrahBasrahIraq

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