Application of Increased Make-up Torque on API Rotary-Shouldered Connections: 
Goodman Diagram vs. Strain Life Model

McCarthy, John F.; Everage, S.; Lee, Kang

doi:10.2523/87190-ms

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…A more recent technical paper [2] presented an elastic-plastic Strain Life Model as an alternative to the application of the Modified Goodman Diagram (MGD) when assessing the effects of higher MUT on RSC. The MGD is an analytical model used to determine how the combination of mean stresses and cyclic stresses influence the fatigue life of RSC [3] .…”

Section: Introductionmentioning

confidence: 99%

The Effect of Increased Make-up Torque on Performance of Rotary Shouldered Connections

Breihan¹,

Muradov²,

Shepard³

2005

Proceedings of SPE/IADC Drilling Conference

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fax 01-972-952-9435. AbstractIn recent years, drilling programs have become significantly more aggressive and challenging.Rotary shouldered connections (RSC) in extended reach and ultra-deep wells face unprecedented loads. Torque is one of the constraints imposed by modern drilling applications on standard RSC. In order to prevent uncontrolled downhole make-up in severe drilling environments, standard RSC are, in some cases, madeup above recommended torque values.This paper discusses the effect of increased make-up torque on the fatigue performance of RSC. It presents the results of full-scale fatigue testing on API NC connections and discusses the correlation with various analytical modeling methods currently in use to determine the suitability of increased make-up torque in specific drilling applications. Make-up torque values ranging from 30% to 90% of the connection torsional strength are compared to determine the full impact of make-up torque on fatigue life.The paper provides drilling engineers additional information to assess the potential risks associated with varying make-up torque in relation to drilling parameters.

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Section: Introductionmentioning

confidence: 99%

The Effect of Increased Make-up Torque on Performance of Rotary Shouldered Connections

Breihan¹,

Muradov²,

Shepard³

2005

Proceedings of SPE/IADC Drilling Conference

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Managing BHA Components Integrity with a Fatigue Management Workflow

Suryadi

Brovko

et al. 2016

IADC/SPE Asia Pacific Drilling Technology Conference

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BHA integrity is important to successful drilling operations. Fatigue failure is the primary cause of twistoffs. There has been no method to predict and monitor fatigue life of BHA components while drilling. Current preventative methods include predefining the collar life based on past experience and tracking the cumulative pumping hours. When total hours reach the predefined life, the collar is junked. This method is inaccurate because the pumping hours do not accurately reflect the fatigue life of a collar. Regular inspections by nondestructive testing (NDT) to detect any cracks should reveral the initiation of fatigue failure. However, a collar can still consume its fatigue life, initiate a crack, and finally twist off while drilling, causing significant loss of time and money. Fatigue damage consists of two stages, crack initiation and crack propagation, with crack initiation accounting for most of the total life. Rotating bending is the driving force for fatigue cracking. It induces cyclic stresses and strains at the stress risers, which are the fatigue-critical features. Fatigue data can be presented in the form of M-N curves, where M is the applied bending moment and N is the total life in number of cycles. The BHA bending moment distribution can be computed with a BHA analysis. Given a bending moment, the cyclic stresses and strains at the most critical feature of the most critical BHA component are typically determined with finite element analysis. The life of the most critical feature can then be calculated with the stress-life or strain-life curve of the collar material. This governs the life of the entire BHA. A fatigue management workflow has been created for planning and execution monitoring phases. During planning, the engineer can calculate the expected fatigue life of the BHA and optimize for the expected duration of the job. The result can be used to select reliable components with sufficient fatigue life for the job. While drilling, this method enables engineer to continuously monitor the consumed fatigue life of any BHA component and make the decision to replace the tool before a failure occurs downhole. After the job, the consumed life can be recorded in the maintenance system to track the remaining life and decide what preventive maintenance is required. This innovative workflow has been implemented to manage BHA integrity for medium to high dogleg severity (DLS). The approach to managing fatigue life enables risk mitigation for BHA integrity, pushing kickoffs deeper, shortening the curved sections, and increasing reservoir exposure, including reentry applications. Field cases have proven that the solution provides engineers with a new tool to reduce fatigue failures by predicting expected fatigue life consumed on a job, selecting correct tools, and proactively managing the drilling risks.

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Drill Bit Connections: A Time for Change

Anderle

Arfele

Hinz

et al. 2017

SPE/IADC Drilling Conference and Exhibition

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Rotary shouldered connections (RSCs) for polycrystalline diamond compact (PDC) drill bits have been unchanged since PDC bits were introduced in the late 1970s. These specifications were carried over from roller cone (RC) bits, which require significantly less torque to fail rock than a PDC bit. Current drilling processes and technologies highlight the need to re-evaluate connection requirements for PDC bits, specifically bits using the 3 1/2 REG connection. The Bakken shale requires extremely long laterals of up to two miles to remain within production zones, which are most economically drilled with a bent housing motor. These long laterals led to significant motor technology improvements for preventing stalls and allowing more weight on bit (WOB), increasing rate of penetration (ROP), and decreasing the number of bottomhole assemblies (BHAs), which reduced drilling costs. These advantages were achieved using a 5-in. motor that has a peak torque output greater than the makeup torque of the 3 1/2 REG connection. Therefore, it is necessary to re-evaluate PDC bit connections. The connection fatigue index (CFI) is used to compare the fatigue life of connections given a set of parameters. It uses the Morrow strain-life equation to predict fatigue life. A unique feature of the equation is that it takes into account both stress and strain in the plastic region, which is crucial because the last engaged thread enters plastic deformation during makeup. The CFI includes Numbered Connections (NC) 35 and NC38 but does not include the 3 1/2 REG connection; therefore, the starting point for evaluation is to perform the calculations for the 3 1/2 REG connection. Fatigue life was evaluated using the CFI for the 3 1/2 REG, 3 1/2 REG with 1-in. stress-relief groove (SRG), NC35, and NC38 connections for a given bending moment. Results from the Morrow strain-life equation predict that the NC35 with a SRG will have the greatest number of cycles to failure of the four connections evaluated. Based on the CFI calculations, the NC35 is predicted to last approximately 800 times longer than the 3 1/2 REG, 40 times longer than the NC38, and 10 times longer than a 3 1/2 REG with 1-in. SRG. The following thread form characteristics account for the exponential increase in life of the NC connections over the 3 1/2 REG: larger pitch diameter, SRG, larger root radius, and reduced taper angle. The NC35 connection was then field tested in a Bakken shale lateral. As well plans are modified for shale drilling and motor technology advances, connection advances are also required. At a minimum, the makeup torque of the connection should be greater than the torsional output of the motor to prevent downhole makeup, mud seal galling, and reduced fatigue life.

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Application of Increased Make-up Torque on API Rotary-Shouldered Connections: Goodman Diagram vs. Strain Life Model

Cited by 3 publications

References 4 publications

The Effect of Increased Make-up Torque on Performance of Rotary Shouldered Connections

The Effect of Increased Make-up Torque on Performance of Rotary Shouldered Connections

Managing BHA Components Integrity with a Fatigue Management Workflow

Drill Bit Connections: A Time for Change

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