Some of the most important aspects to consider during the design, construction and productive life of a well are the amount and nature of the risks associated with the conveyance of downhole instruments to acquire critical formation evaluation (FE) data while the hole is open and downhole tool strings needed to service the well after installing the completion and production hardware. With the increase in popularity of long, deep and tortuous wells, mainly in the high-cost operating environments, these risks have become more acute. A new methodology, based on forces modeling and best practices gathered over decades, has been developed to take full advantage of new conveyance technologies intended to alleviate or eliminate these risks. This paper describes the new conveyance risk-reduction technologies and their areas of applications, the newly developed risk management methodology and the economical value these innovations bring to our industry. To demonstrate the merits and practical aspects of such an enterprise, we discuss here the following case study: Introduction As it became more difficult to discover large oil and gas fields in relatively shallow and friendly environments, the industry stepped out into more complex and less familiar territories requiring the creation of new technologies and methods designed to drill, complete and produce longer, deeper and more deviated and tortuous wells. Advances in directional drilling technology increased the ability to exploit small-to-medium-sized reservoirs from a single drilling location. This resulted in large improvements of the productivity and the profitability of offshore projects that were previously considered marginal. During the initial well construction phases, any well operations delays encountered defer production in the well under construction and in the production from all subsequent wells that will be drilled from the same location. These changes to the reservoir exploitation strategy demand the use of top-of-the-range drilling technologies which provide improved drilling performance in this demanding environment. As the complexity of the wells increased, the aggregated cost of all well interventions increased. In particular, the rig cost resulting from the amount of time required for these operations became a point of serious concern when planning the well intervention operations. The use of traditional conveyance methods in this type of complex wells typically required longer deployment times than in more conventional wells. Consequently, the projects overall costs were much higher due to the increased rig time costs needed to avoid the perceived risks associated with deploying equipment in these wells using less conventional technologies. To illustrate such a situation, consider what was commonly done to execute an openhole formation evaluation program in a low-angle, 20,000 ft well that included a 5,000 ft openhole section with an average deviation of 65 degrees:
The increased use of deep, highly-deviated and tortuous wells has increased the risk of wireline logging tool strings getting stuck downhole. If this risk is not appropriately managed and effectively mitigated, significant financial exposure can result from the cost of the multi-day fishing operations, the lost-in-hole and replacement charges, and -most importantly-the loss of opportunity to acquire critical subsurface data. This exposure is even higher in environments with large operating costs, such as deep water. Historically, formation testing and fluid sampling tools have been among the most frequently stuck, fished and lost logging equipment. On the other hand, formation testing continues to provide some of the most essential information for reservoir characterization. Therefore, managing the risks associated with tool deployment is essential. This paper discusses the sticking mechanisms of formation testing and fluid sampling tool strings, and provides specific recommendations for the planning and execution of such operations. The various factors that lead to differential sticking or keyseating of the tool string and the wireline cable are discussed. A dataset that explores a wide variety of situations is analyzed to provide a pragmatic guideline for effective mitigation of tool and cable sticking. A specific example from highly deviated deep water well is shown to highlight the significance of proactive planning.
Some of the most important aspects to consider during the design, construction and productive life of a well are the amount and nature of the risks associated with the conveyance of downhole instruments to acquire critical formation-evaluation data while the hole is open, and downhole toolstrings needed to monitor or service the well after installing the completion and production hardware.Wells with horizontal sections in excess of 5,000 ft present significant challenges to the existing well intervention methods and technologies; in particular, production-logging programs under high-production rates using downhole tractor conveyance have proven to be particularly difficult to plan and execute in these wells. This paper describes the extreme conditions offered by these long horizontal wells, the underlying physics that support modeling of mechanical and hydraulic lift forces, the hazards present when conducting logging operations under flowing conditions using wireline and downhole tractors, the relevant conveyance risk-reduction technologies and methods to successfully plan and execute these extreme operations.To demonstrate the operational merits and practical aspects of the methods and solutions presented, a case study based on a real operation is included.
With the increased popularity of long, deep and tortuous wells, mainly in high-cost operating environments, the risks associated with wireline logging operations and interventions in these modern complex wells have become more acute. Several risk-reduction technologies and forces-modeling software capable of simulating these operations have been developed and successfully applied. This paper describes several high-impact supplementary modeling utilities that have been implemented within a leading forces-modeling software that enable users to adequately plan and execute complex wireline operations. The utilities are designed to perform dedicated analyses using the project data already included in the wireline operation models. The following utilities are presented in this paper: Pump Down AnalysisCable Tension AnalysisFriction Coefficient AnalysisTool Depth Creep AnalysisStuck Pipe AnalysisStuck Wireline/Tool AnalysisTool Free Fall Analysis The effective use of these utilities significantly reduces the non-productive rig time associated with recovery operations and can assist with optimizing pump down operations, accurate positioning of downhole tools, as well as locating tool strings dropped in the well. Use of the utilities can also improve the accuracy of wireline downhole conveyance models while enhancing the ability to perform high-tension operations in a safe and efficient manner. The economic value resulting from the use of these applications is directly associated with the aggregate daily rig cost and the financial cost of the resulting deferred production volume during non-productive time, which together can be in excess of a million dollars a day. This paper provides descriptions and application examples of these supplementary wireline modeling utilities, the logic and calculations supporting them, and the resulting economic benefits they deliver.
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