Integrated mechanical earth model and quantitative risk assessment to successful drilling
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ORIGINAL PAPER-PRODUCTION ENGINEERING
Integrated mechanical earth model and quantitative risk assessment to successful drilling Alireza Noohnejad1 · Kaveh Ahangari1 · Kamran Goshtasbi2 Received: 28 February 2020 / Accepted: 6 October 2020 © The Author(s) 2020
Abstract Use of vital geomechanical parameters for determination of safe mud pressure window is generally associated with high level of uncertainty primarily because of absence of sufficient calibration data including laboratory and field test information. The traditional deterministic wellbore stability analysis methodologies usually overlooked the uncertainty of these key parameters. This paper exhibits implementing a quantitative risk assessment technique on the basis of Monte-Carlo modeling to consider uncertainty from input data so as to make it possible to survey not just the likelihood of accomplishing a desired level of wellbore stability at a particular mud weight, but also the impacts of the uncertainty in each single parameter on the wellbore stability. This methodology was implemented to a case study. The most important parameters have been recognized using a sensitivity analysis approach in which the outcome of this QRA procedure suggests the mud weight window with likelihood of well drilling success which can elude the wellbore collapse and lost circulation events. This sort of stochastic approach to deal with anticipated safe mud weight window can guarantee stable wellbore with considerable cost viability associated with drilling success. The technique built up in this paper can give the scientific foundation for assessment of wellbore stability under complicated geological circumstances. It was likewise noted that based on sensitivity analysis, uniaxial compressive strength and maximum horizontal stress are the most effective parameter in estimation of mud weight window. This accentuates the significance of trustworthy determinations of these two parameters for safe drilling of the future wells in the field. Keywords Safe mud weight window · Uncertainty analysis · Quantitative risk assessment · Sensitivity analysis · Probability of drilling success
Introduction Proper mud weight plays a vital role in wellbore instability studies in oil and gas industry. As most of the current drilling projects including well construction and field development are challenging, safe mud weight windows have a deteriorate effect on the time schedule of the project and can drastically lessen non-productive time (NPT), issues related to instability of wellbores and unwanted costs on drilling operation (Plumb et al. 2000; Elyasi et al. 2013). To minimize the risk of wellbore instability and following technical/economic consequences, a suitable pre-drilling * Kaveh Ahangari [email protected] 1
Department of Mining Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Mining Engineering, Tarbiat Modares University, Tehran, Iran
2
geomechanical scheme needs to be developed. Building mechanical earth model (ME
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