The module includes additional tools integrated into the program kernel. This module simulates fatigue and stress level based on the well trajectory profile, as well as the drillstring description and its operational history. Dsd uses a stiff string model the most accurate drill string model. Paper open access fatigue failure analysis of drilling tools. A dp fatigue wear generally occurs because the outer wall of the pipe in a dogleg is stretched resulting in additional tension loads. Bha design 32 bit is a complete analysis for bottom hole assembly design bha design. Drillscans drilling engineering software improves performance. Detailed models of downhole tools can be incorporated into a full drill string analysis to study their influence on dynamic string behavior. As downhole pressures and temperatures increase along with drill lengths tool performance must be optimized for precise positioning and control, designed to operate in more corrosive environments at high pressure and high temperature, and be able to withstand fatigue. Nonetheless, drill string failures continue to occur, most often as a result of some form of metal fatigue. Bha design including bha reference and graphic complete analysis for bottom hole assembly design bha design. Bha design including bha reference and graphic drillingsoftware. Failure analysis of drillstring in petroleum industry.
The course provides a comprehensive treatment of drill string design as well as the avoidance of operational problems and wear on equipment following the api recommended practices for design and operating limitations as well as the standard ds1 for design and inspection. For example, fatigue may account for more than 70% of the total failures. Based on linear damage accumulation law, this paper investigates the fatigue problem of drillstrings in time domain. What we as an industry must do to seriously impact the problem of drill string fatigue is the following. In other words, cumulative damage occurs when the drill string is subjected to cycles of stress that accumulate damage to the drill string over time.
They prove the practicability of the ansys software and provided the theory bases for optimizing drilling parameter of deep well and decreasing drill string fatigue failure. As stress cycles continue, these cracks grow until the affected component leaks or breaks, like the bottomhole assembly bha box. This paper reports fullscale tests on threaded connections used in drill strings. Torque and drag nuts and bolts pegasus vertex, inc. Adams is the worlds most widely used multibody dynamics simulation software. Apr 26, 2018 fatigue is a cause of drill string failures. The calculation results reveal the reason of frequent failure of drill collar thread. Downhole vibration causing a drill collar failure and solutions. Results under both deterministic and random excitations are compared against each other. The final durability postprocessing analysis is performed using the um durability module. The ds1 fatigue analysis module enables any well plan to be audited for compliance with the ds1 standard design, thereby ensuring that fatigue in the drill string and bha is both evaluated and minimized.
This paper describes software designed to predict the drill string. Fatigue of drill string connections journal article osti. Dynamic stress analysis of drill string in gas drilling. Sn curves use your own or state of the art published sn curves. Drillscan engineers develop and deliver expert solutions for any stage of wellconstruction, from pre analysis through realtime operations to post analysis. Drill string axial vibration and sonic head analysis. Given this rate of fatigue development, the drill string would be rejected due to mechanical tool joint or pipe body abrasion rather than fatigue wear. Drillstring integrity simulate fluid flow and heat transfer during drilling operations, for full transient analysis. Through multiaxial fatigue life prediction of drill collar in gas drilling of well a1, the fatigue life of api thread is approximately 2. Multiaxial fatigue life prediction of drill collar thread in. Range analysis calculation tool automatically performs a full analysis at varying depths and provides a summary of surface results.
Apr 24, 2018 estimation of cumulative fatigue wear in the drill string. Fatigue estimation of drillstring and drillpipe threaded. For a given makeup torque the allowable operational torque and external tensile load can be determined. Model validation plan and support lab testing and instrumented well testing for validation. Analysis on drill string vibration in deep wells by ansys. The fatigue model, which has been implemented as one of the key components in the drilling analysis workflow, provides engineers with the analysis capability to identify the potential factors influencing the integrity of bha components. Dsd drill string dynamics mechanics simulation software. In many cases, drill string fatigue is progressive. Two case studies validated the drillstring fatigue prediction model.
Introduction uring oil and natural gas, borehole drilling operations, there are many engineering problems to contend with, as discussed in 1, including the failure of the drill string ds owing to the combined compression, buckling and torsional stresses encountered. Mathematical modeling and prediction of drill string. All sorts of resonance frequency of drill string are obtained and the fatigue state along the drill string can be shown with the animate shape and vector plot. Knowledge of the allowed stability region of drill pipes and collars is the first step to having an optimal design of drill string in specified conditions of wellbore. Both drill string fatigue and interference with weight transfer to the bit occur. With lack of sufficient knowledge of drill string stability region may be used pipes with more resistance for more safety. Only commercial software which can model the full dynamics of the drillstring and wellbore to reproduce damaging effects such as stickslip and whirl. Fatigue of drill string connections journal of offshore. Universal mechanism the software for modeling of dynamics. Analysis of fatigue failure factors of ultradeep well drilling tools different from conventional drilling, ultradeep well drilling tools can withstand higher drill string weight, higher downhole temperature, and longer drilling fluid corrosion time.
The drill string is connected to the vibration generation device proposed in this study, and it is another purpose of this study to analyze the effect of vibration on. Bha design analysis and critical design features of a bha. Um monorail train contains the following main components. Rainflow algorithms are developed to count the stress cycles. Fatigue damage accumulates until a crack initiates. Drill string and components this chapter of the iadc drilling manual is concerned with the specifications, operating data, and the care and handling of drill string. Fatigue analysis procedure for drill string schlumberger. This page describes the caebased durability analysis that is being implemented in universal mechanism software to predict the fatigue damage of parts of mechanical systems. Moreover, as a result of the cutting action of the drill bit, as rock with a variety of physical properties is penetrated, stochastic loading on the ds is excited leading to the possibility of.
Its a different matter to give a drilling engineer specific rules to follow to achieve these benefits. Time domain fatigue analysis gives accurate predictions at the cost of long calculating time. The program allows up to 4 sections of drill pipe, four sections of hwdp, and four sections of drill collars. The fatigue analysis considers well bore curvature. The analysis starts with the dynamical hybrid model in universal mechanism. Predicting and preventing drill string fatigue failure.
Drillscan energy improve your drilling performance. Nov grant prideco analysis data acquired in tests for drilling tool fatigue indicate that repeated bending was a common form of drill string fatigue. It will also discuss troubleshooting of the problems that may occur. Simulate fatigue and level of stress at any point of the string. Drill string simulation allows drilling engineers to conduct numerous whatif scenarios and identify combinations of surface parameters, control systems, or other bha or downhole tool design parameters to avoid drilling dysfunctions.
A new approach to the analysis of drillstring fatigue. Its easy to show the fatigue benefits of lower operating stress and more benign environments. Reducing costly failures with advanced drillstring modeling. Rotating a joint of drill pipe while it is bent around a dogleg causes fatigue damage to occur in the wall of the pipe. Fatigue is tendency of material to fracture under repeated cyclic stress and chemical attack. The flexibility characteristics of the structural parts are incorporated into um model using a modal formulation based upon component mode synthesis. Stress distribution determine the stress distribution along any drill string and equipment. Our software modules are intuitive and supported by an expert technical team known for their service excellence. It probably accounts for upward of eighty percent of all drill string failures. Bhavya technologies is an independent engineering software development company that provides consulting services in the form of software solutions for mathematically complex engineering problems. Wellcat software is a comprehensive and modular suite of applications that work together to address a wide variety of casing and tubing challenges. Fatigue damage will accumulate at many highstress points in the drillstring, and fatigue cracks will form. To solve an engineering problem of severe vibration and frequent failure of drill string in gas drilling, we analyzed vibrating behaviors of drill string during gas drilling based on a dynamic.
Being cumulative and irreversible, repeated bending is directly related to application time. The position of drill string can be changed to suite all well designs all dcs or all hwdp. Drill string vibration is a very prevalent phenomenon. The method developed by the specialists, of the drilling department in the siberian service company, is an effective way of estimating the cumulative fatigue wear in the drill string during well construction, based on wellbore path and drilling process. It lets you build and test virtual prototypes, realistically simulating on your computer, both visually and mathematically, the fullmotion behavior of your complex mechanical system designs. Development of and validating a procedure for drillstring. Program package universal mechanism includes a specialized module um monorail train for analysis of 3d dynamics of both single vehicle and trains. A concise background is given concerning the inservice environment and loading conditions on the connections. Index terms deflections, drill, principal, stresses, strings i. Pdf fatigue life prediction of drillstring subjected to. Fatigue life prediction of drillstring subjected to random loadings. Sep 10, 2014 dogleg severity analysis the most common dp failure is fatigue wear. It can be used by drilling engineers to model all types of bhas, e. Each element in the bha can be individually analyzed to observe fatigue across several points along any element.
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