TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOpen hole gravel pack completions can have many advantages over comparable cased hole completions. This is especially true for horizontal well applications. However, because no perforations are present to penetrate the filtercake, borehole conditioning prior to gravel packing is critical to ensure good well productivity. To address this issue various borehole cleanup techniques have been developed. These different techniques have been adopted to address specific reservoir and economic conditions. Various levels of success have been realized for these techniques, with their development leading to an improved understanding as to which steps are critical for success under any circumstance. This paper reports performance results from gravel packed horizontal wells completed in the East Wilmington Field. In addition, techniques applied elsewhere are reviewed. The conditions that must be met in all displacement techniques to ensure a successful completion are outlined, as will the benefits and drawbacks of each of the commonly applied methods. Guidelines for selecting a wellbore cleaning procedure to employ in specific situations are provided.

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. Methodology and Calculation The dynamic analysis model is based on a forced frequency response (FFR) analysis to solve for resonant frequencies. In addition, our mathematical formulation includes viscous, axial, torsional and structural damping mechanisms. With careful consideration of input parameters and judicious analysis of results, we were able to demonstrate that drillstring vibration can be avoided by determining the three dimensional vibrational response at selected excitations that are likely to cause them. Also, the analysis provides an estimate of relative bending stresses, shear forces, and lateral displacements for the assembly used. Based on the study, severe vibrations causing potentially damaging operating conditions were avoided, a situation which was a major problem in nearby wells. The avoidance of severe vibrations resulted in documented savings in time and cost. Simple guidelines were provided to estimate the operating ranges of the drilling parameters to mitigate and avoid downhole tool failures. Extensive simulations were carried out to compare the data from the downhole vibration sensors, and the paper includes one data from a severe vibration incident where by the model estimated, predicted, and avoided severe vibration. For convenience the model2 is explained briefly in the following paragraphs. This incident took place on an offshore well. The model2 solves the linearized form of the following equation in which all the displacements and forces vary harmonically in time at the same frequency.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOpen hole gravel pack completions can have many advantages over comparable cased hole completions. This is especially true for horizontal well applications. However, because no perforations are present to penetrate the filtercake, borehole conditioning prior to gravel packing is critical to ensure good well productivity. To address this issue various borehole cleanup techniques have been developed. These different techniques have been adopted to address specific reservoir and economic conditions. Various levels of success have been realized for these techniques, with their development leading to an improved understanding as to which steps are critical for success under any circumstance. This paper reports performance results from gravel packed horizontal wells completed in the East Wilmington Field. In addition, techniques applied elsewhere are reviewed. The conditions that must be met in all displacement techniques to ensure a successful completion are outlined, as will the benefits and drawbacks of each of the commonly applied methods. Guidelines for selecting a wellbore cleaning procedure to employ in specific situations are provided.

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