During the last few years, advances in completions and sand-control technology have enabled development of many high-end technologies that allow complex operations to be conducted. During the life cycle of a well, one of the key operational goals is to maximize the well's net present value (NPV). Typically, the majority of the well completion budget is allocated to the drilling phase. If, however, the drilling costs are not kept within planned budget and time parameters, it becomes necessary to reduce the time and cost in the completion strategies to enable the project to be completed within cost constraints.
This paper discusses a new single-trip perf-pack gun hanger (STPP-GH) system that reduces cycle times, and thus, costs. The STPP-GH completion system provides a completion in which perforating and frac-packing and/or gravel packing for a zone of interest can be performed in a single workstring trip. When using this system, the operator can realize such benefits as reduced completion fluid losses, reduced formation exposure, and increased well-control safety. These advantages result from the reduction in operational time when compared to traditional perforating and gravel-pack operations.
In the early 1980's, the first one-trip perforate and gravel-pack systems were introduced. Since that time, most major service providers have marketed various versions of a one-trip, perforate and gravel-pack system. While these systems have not developed into "everyday" completion methods, they are being used on wellbores that meet the criteria of the design. There are a number of reasons for this limited gain in use in spite of the advantages that this type of system can offer. All wells are not drilled with sufficient rathole below the proposed interval to accommodate the perforating gun assembly after firing. Longer-interval lengths and more-deviated hole angles can make debris management more difficult to attain. There is a question of system reliability as a function of complexity. The systems are complex, combining multiple functions into one system, which if any malfunction should occur, would require that the whole system be pulled from the well. If the system becomes stuck, fishing it from the wellbore could be more difficult than fishing a conventional gravel-pack completion.
One-trip, perforate and gravel-pack systems are success-fully being used today within the designated operating envelopes; however, key activities such as having good operational procedures and pre-job overviews must be conducted if a successful completion is to result.
These systems have been designed so that they can be used in a myriad of sand-control scenarios; for example, frac packs, high-rate water packs, and gravel packs. Like most of the advanced completion systems in use today, the greatest savings will be on projects with extended depths, extreme wellbore geometry, and/or scenarios where higher-cost completion fluids are needed. In as much as greater savings are typically realized or associated with more risk, this system can also perform just as reliably and as expected on shallower wellbores in which the main drivers may include well control, reduced formation damage, and enhanced operational safety rather than the cost-reduction benefit.