The aim of this paper is to demonstrate that stochastic analyses can be performed on large and complex models within affordable costs. Stochastic analyses offer a much more realistic approach for analysis and design of components and systems although generally computationally demanding. Hence, resorting to efficient approaches and high performance computing is required in order to reduce the execution time.A general purpose software that provides an integration between deterministic solvers (i.e. finite element solvers), efficient algorithms for uncertainty management and high performance computing is presented. The software is intended for a wide range of applications, which includes optimization analysis, life-cycle management, reliability and risk analysis, fatigue and fractures simulation, robust design.The applicability of the proposed tools for practical applications is demonstrated by means of a number of case studies of industrial interest involving detailed models.

This paper addresses the most recent developments concerning the application of the P-C expansion method within the Stochastic Finite Element (SFE) analysis, in particular considering computational solid mechanics. More specifically, the focus has been on the use of the method for the propagation of the stochastic structural responses due to the extensive amount of contributions in this context. Numerical examples presented in the literature are listed in this regard, in order to shed some light on the range of applications, especially in terms of the probabilistic dimensionality of the problem. Furthermore, the recently emerging utilization of the method within the modeling of uncertain input parameters is covered briefly. With this contribution, it is aimed to present an overview on the state-ofart of the P-C literature and the capabilities of the method.

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In recent years, the phenomenon of drill string torsional oscillation at frequencies over 50 Hz has been well documented. This high frequency torsional oscillation (HFTO) creates cyclic fatigue loading on bits and drilling tools within the bottom hole assembly (BHA) and thus limits tool life and drilling performance. However, few models exist which can predict occurrence of HFTO and its severity. To our knowledge; none of these models consider the entire drilling system including the bit-rock interaction, downhole drive(s), BHA design, and surface drilling parameters, and hence there is a need to develop a system model for HFTO mitigation. A 3D transient drilling dynamics model has been extended to study the severity of HFTO and cyclical loading to drilling tools. The accuracy of the model was validated by theoretical calculation, and high frequency downhole data. An example analysis was conducted to evaluate drilling system design performance in terms of HFTO risks. Good correlation was found between the analysis and field data collected from the Permian Basin. Advanced models were developed for mud motors and rotary steerable system (RSS) tools. After conducting a full drilling simulation, the drilling system behavior under HFTO can be fully described. Cyclical torque loading of differing magnitudes and frequencies were observed for different BHA components depending on HFTO vibration mode, HFTO severity and BHA design. PDC cutters were subjected to different cyclical loading depending on bit design, formation and HFTO conditions. The mud motor power section was found to undergo high frequency cyclical loading which could accelerate its rubber degradation. Since the failure of PDC cutters and the degradation of mud motor power sections have a critical effect on drilling performance, the importance of mitigating HFTO cannot be underestimated. By evaluating the loading conditions, an optimized drilling system can be selected. Field data has proved the validity of this approach. The methodology presented in this paper offers a new way for the industry to systematically mitigate HFTO by considering the rock drilled, bit design, mud motor utilized, the mechanics of RSS and other tools in the BHA, as well as drilling parameters. The usage of this approach can reduce premature drilling component failure and improve drilling performance, especially in the high energy drilling applications found in North America Land and other areas.

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The most traditional polycrystalline diamond compact (PDC) cutter technology is composed of a flat surface that contacts the rock to be sheared and removed throughout the drilling process. The necessity to overcome engineering limitations related to PDC capability drove the industry to innovate cutter shapes and 3D surfaces to interact with the rock. A new hyperbolic diamond element (HDE) bit has been developed to improve drilling efficiency in soft formations compared with conventional polycrystalline diamond compact (PDC) cutters. The design concept and bit utilization theory, laboratory validation, including full-scale drilling simulator testing, implementation of the time-based dynamic bit and drillstring modeling system, as well as the operator's field drilling results from the Niobrara shale play of the DJ Basin, Colorado, USA are presented. The HDE development, from concept to validation and field deployment, consisted of a multidisciplinary approach that combined proprietary knowledge, manufacturing, and computational analysis. Creating the HDE concept required an overall understanding of shaped diamond elements (SDEs), their applicability, field results, and mechanical properties and outputs. After creating the concept, proprietary manufacturing processes, single cutter-rock experiments, and full-scale bit-rock testing were used to validate the innovative new SDE. Based on success with the baseline drill bit design—a PDC bit with a different SDE—as well as results from implementing HDEs into a time-based dynamic modeling system used to predict field performance improvements, a DJ Basin operator agreed to test the new HDE bit. After the first 10 field tests, the HDE bit resulted in a 20% improvement in overall ROP compared with the baseline PDC bit design. The HDE drill bit improved drilling efficiency and lowered mechanical specific energy (MSE) in both the rotating and sliding drilling modes. These results were in line with full-scale bit-rock testing, which indicated a 10 to 20% ROP improvement for the same weight-on-bit (WOB) in various formation types. Furthermore, the results were obtained without increasing bit torque, which is a performance parameter important for positive displacement motor (PDM) -driven bottomhole assemblies (BHAs). Field testing also indicated that the cutting structure durability was improved, which increased drilling system reliability for the operator. Insignificant or no damage was observed over the HDE bit cutting structure after field tests. The new HDE drill bit efficiently transfers drilling system energy into formation removal without increasing reactive torque to uncontrollable or catastrophic levels. Due to rock-cutting efficiency and cutter durability improvements, SDEs are quickly replacing PDC cutters in various drilling applications worldwide. The concept and laboratory validation delivered a unique and innovative cutting technology for soft formations. Field experience and software modeling combined BHA and nonbit factors during the HDE bit design process to achieve the field performance using the new technology.