A relationship to estimate the optimal drilling mud pressure in oil wells in carbonate formations of southern Iran oil fields

Document Type : Research Article

Authors

Imam Khomeini international university

Abstract

The analysis and prediction of well wall stability is considered as one of the most important and critical points in drilling operations. The instability of the well wall is one of the most serious problems in the oil and gas well drilling industry because it can lead to loss of part of the well or its entirety, which ultimately results in delays in operations, increased costs Drilling and delay will occur at the time of operation. One of the most important ways to cope with this problem is to determine the optimal drilling mud pressure. The pressure of the mud should be so high that it is in proportion to the amount of tension in the pores and pockets, and to the extent that the well after the large tensile fractures caused by the high pressure of the mud, as well as the shear fractures due to low pressure It will be safe. The aim of this study was to obtain a relationship to estimate the optimal drilling mud pressure in wells in the oil-rich regions of southern Iran. To achieve this goal, information of a number of oil wells was collected in the oil fields of southern Iran and then, using FLAC2D software, a limited-scale numerical program limited to oil wells, oil wells were analyzed in two Equilibriums and equilibriums modes have been investigated. Ultimately, for determination of the stability of the optimum drilling mud in the elastoplastic method, the method of determining the normalized level of NYZA has been used. In each step, optimal drilling mud pressure is calculated and finally, a correlation is presented using SPSS software through multivariate linear regression. This relationship is a linear relationship in which the optimal drilling mud pressure is estimated by parameters of minimum and maximum horizontal tensions, pore pressure, internal friction angle and cohesion.

Keywords

References

[1] G. Xu, Wellbore stability in geomechanics, University of Nottingham, 2007.
[2] D. Wiprut, M. Zoback, High horizontal stress in the Visund field, Norwegian North Sea: consequences for borehole stability and sand production, in:  SPE/ISRM Rock Mechanics in Petroleum Engineering, Society of Petroleum Engineers, 1998.
[3] S. Shahbazi, Numerical modeling of the oil well behavior in shale formations M.Sc. Thesis, Imam Khomeini international university, 2015. (in Persian).
[4] N. Sasaninia, F. Rezai Mirghaed, A. Shabkouhi kahkesh, Determination of the optimal interval of drilling mud pressure using FLAC software in one of the oil fields of southwest Iran, in:  the international conference of research in science and technology, 2015. (in Persian).
[5] O. Farzai, S.A. Khatibi, Determination of optimal mud pressure in Kangan and upper Dalan formations based on core data, in:  the 2nd national conference on petroleum Geomechanics 2015. (in Persian).
[6] R. Asgari, M. Heidarizadeh, H. Memarian, Studying the stability of the well and determining the range of mud weight using NYZA method in one of the oil fields in southern Iran Oil and gas exploration and production, 96(146) (2017) 59-65. (in Persian).
[7] S.M. Fatemi Aghda, M. Talkhabo, A. Taheri Haji Vand, Geomechanics modeling and determination of safe mud window to prevent instability of the wellbore wall (case study: one of the oil fields in southwest Iran), in: the national conference on geology and exploration of resources, Shiraz, 2014. (in Persian).
[8] A. Movahedinia, M.K. Ghasem Alaskari, M.Yarahmadi, Estimation of optimal mud pressure using different failure criterion in directional wells (case study: well 5sk2 in Salman oil field), Petroleum Research, 23(73) (2013) 104112. (in Persian).
[9] R. Asgari, M.A. Aghighi, N.A. Ghavidel, R.  Balghan Abadi, The stability of the wellbore and the determination of optimal mud pressure in one of the oil fields in southern Iran, in:  the first oil geomechanics conference, 2015. (in Persian).
[10] M.A. Chamanzad, S. Nowruzi Bazminabadi, A. Ramezanzade, B.V. Tokhmchi, H. Nowruzi, Geomechanical modeling and determination of safe mud window (case study: a well in Azadegan oil Field), in:  The first national conference on petroleum geomechanics, 2015. (in Persian).
[11] Sh. Maleki, M. Ebrahimi, A. Moradzade, F. Sadeghzade, Determining the optimal mud weight using the MohrCoulomb failure criteria for the stability of oil wells (Case study: one of the oil fields of southern Iran), in:  the first petroleum technical conference and exhibition, 2013. (in Persian).
[12] E. Fjar, R.M. Holt, A. Raaen, R. Risnes, P. Horsrud, Petroleum related rock mechanics, Elsevier, 2008.
[13] M.S. Ameen, B.G. Smart, J.M. Somerville, S. Hammilton, N.A. Naji, Predicting rock mechanical properties of carbonates from wireline logs (A case study: Arab-D reservoir, Ghawar field, Saudi Arabia), Marine and Petroleum Geology, 26(4) (2009) 430-444.
[14] J.-L. Yuan, J.-G. Deng, Q. Tan, B.-H. Yu, X.-C. Jin, Borehole stability analysis of horizontal drilling in shale gas reservoirs, Rock Mechanics and Rock Engineering,46(5) (2013)1157-1164 .
[15]  A.R. Najibi, M. Ghafoori, G.R. Lashkaripour, M.R. Asef, Empirical relations between strength and static and dynamic elastic properties of Asmari and Sarvak limestones, two main oil reservoirs in Iran, Journal of Petroleum Science and Engineering, 126 (2015) 78-82.
[16] A.H.A. Ali, T. Brown, R. Delgado, D. Lee, D. Plumb, N. Smirnov, R. Marsden, E. Prado-Velarde, L. Ramsey, D. Spooner, Watching rocks change—Mechanical earth modeling, Oilfield Review, 15(1) (2003) 22-39.
[17] S. Maleki, R. Gholami, V. Rasouli, A. Moradzadeh, R.G. Riabi, F. Sadaghzadeh, Comparison of different failure criteria in prediction of safe mud weigh window in drilling practice, Earth-Science Reviews, 136 (2014) 36-58.
[18] S. Khan & D. Zou, Analysis of wellbore stability in underbalanced drilling, in:  Proceedings of the International Symposium of the International Society for Rock Mechanics, Liège, 2006.
[19] C.D. Hawkes, P.J. McLellan, Modeling of yielded zone enlargement around a wellbore, in:  2nd North American Rock Mechanics Symposium, American Rock Mechanics Association, 1996.
[20] a.M.R.R. M. Esmailian, Comprehensive SPSS 22 Help ublished by Dibagaran Tehran Art & Cultural Institute., Tehran, 2015.
Amirkabir Journal of Civil Engineering
Volume 52, Issue 10
January 2021
Pages 2401-2414

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