Damages and Repairs on Drillpipe Connections
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 151253, ’Comprehensive Review of Damages and Repairs on Drillpipe Connections,’ by Thomas M. Redlinger, SPE, P. Steven Griggs, and Albert Odell, Weatherford International, and Stein Bergo, EuroIncon A/S, prepared for the 2012 IADC/SPE Drilling Conference and Exhibition, San Diego, California, 6-8 March. The paper has not been peer reviewed.
The drilling industry has experienced major changes in both drillpipe connections and related inspection criteria. Many operators and contractors regularly use premium drillpipe connections to drill all sections of their wells. There are few or no established statistical data available to budget repairs in any given well program. This study reviewed data from two inspection databases covering more than 200,000 joints of drillpipe. The databases contain inspection records for premium, double-shoulder, and American Petroleum Institute (API) connections. The objective was to provide a basis for budgeting repair costs.
Introduction
A financial surprise in well planning can be the cost of repairing drillpipe. These costs can be high, and, in some cases, the damage incurred can result in the downgrading and replacement of an entire string of drillpipe. This is not the normal case, but what is? The industry has been inspecting drillpipe for decades, meticulously recording the state of the drillpipe during the inspection; but what has been done with this information? Many drillers have developed personal knowledge of a “normal” amount of damage for their drilling conditions, but this information is rarely shared or placed in the public domain for comparison. As a result, a full understanding of the inspection data is lacking. Also, the inspection, inspectors, and standards vary by customer, geographic region, well profile, rig, drilling contractor, and rental company.
A better understanding may be gained after tracking several databases of inspection data and damage results for the last several years. The information contained within these databases should form a basis for the drilling community to understand the average results and the variations in damage to drillpipe connections.
Drilling Complexity
Drilling complexity has changed significantly over the last few decades, and wells are drilled routinely that were considered “ultradeep” or “extended reach” 20 years ago. Therefore, revisions have been made to ensure that the drillstem elements are fit for purpose, requiring inspection standards to evolve also. A driver for increased scrutiny of drillpipe inspections in the 1990s was the increased use of horizontal drilling. The change in drilling practice gave rise to a significant fatigue damage on the drillpipe. To ensure that the drillpipe would survive increased drilling challenges, operators, contractors, and rental-equipment providers improved their inspection standards significantly. However, the change to more-frequent or more-rigorous inspections has not necessarily led to better pipe quality, and, without a mechanism in place to track them, the effect of these changes remains masked in the other process variables.