Abstract
In recent years, there has been a greater emphasis on technical limits with respect to drilling operations. Oil and gas companies strive to be amongst the highest ranked in operational efficiency with respect to industry related benchmarking statistics. Increasingly complex drilling scenarios, both surface and down hole, coupled with extremely high operating day-rates provide a challenging environment for those partaking in such operations. The risks are high, but the rewards are as well. Companies that can operate efficiently in such scenarios will most certainly reap the rewards.
Understanding technical limits and achieving operational excellence requires proper planning. Unfortunately, proper planning is only a part of the equation. The complexity of the subsurface environment generally results in deviation from planned operations. These deviations may result in significant non-productive time or in equipment failure. Reducing such incidents requires knowledge that the incident took place. Knowledge that the incident took place requires accurate data mining and retrieval as there may be significant time between operations, and knowledge transfer can be lost due to personnel changes. Additionally, an understanding of the root cause of an incident needs to be understood to prevent future incidents. This is generally more difficult to get a handle on. Applying post failure analysis utilizing engineering software applications is an essential part of determining the causes of non-productive time incidents and equipment failures. One could also surmise that it is a critical part of the planning process even though the analysis is after the fact. Reviwing lessons learned is a critical part of any planning process.
In high risk, high cost environments, such as ultra-deep, ultra-deep waters, refining advanced technologies for successful completion of wells is paramount. Challenges are still very much associated with complex BHAs (bottomhole assemblies) and with the vibration of the drillstring. The more widespread use of sophisticated downhole tools — for both directional telemetry and for logging while drilling applications (as part of the front line data acquisition system within the drilling process) — has meant that reliability is of prime importance1–5 . This paper presents and validates an existing model to predict severe, damaging vibrations. The paper also reviews analysis techniques and guidelines to successfully avoid the vibration damage to downhole tools and their associated down hole assemblies.
