TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractConventional gas development wells in prolific carbonate reservoirs before bigbore completions were introduced do not produce to full potential due to tubing constraints. This phenomenon is observed today in several mature, carbonate basins offshore Malaysia developed back in the early 1980s. At that time, the typical tubing configuration was a 7" completion string run in 9 5/8" production casing. This configuration limits subsequent tubing change out workover options to 7 5/8" tubulars resulting in only a modest 10% gain in well capacity through improved outflow performance. This paper will present the results and economic benefits of this field trial, which is the first of its kind in the world. Details encompassing the conceptual solid expandable completion design, modifications and improvisation required for this first-of-its-kind SET gas well workover, and the required SET installation sequence will also be discussed.
Gas wells completed in prolific reservoirs before the advent of bigbore completions do not produce to full potential due to tubing constraints. This phenomenon was observed in several mature, carbonate gas fields offshore Malaysia developed back in the early 1980s. At that time, tubing configuration was limited to 7" completion run in 9 5/8" production casing. Given the size of the production casing, any workover option to enhance outflow performance was limited to recompletion with 7 5/8" tubulars which would result in a 10% gain in well capacity through improved outflow performance.The advent of solid expandable tubular technology in the new millenium has opened up a revolutionary possibility for transforming a conventional well with 7" tubing to a bigbore producer. The concept involves installing and expanding extended lengths of 7 5/8" solid tubulars inside 9 5/8" casing. This will yield a production conduit with a larger internal diameter than conventional 7 5/8" tubulars. Thereafter, gas production occurs through the solid expandables based on a philosophy similar to long casing flow monobores.A field trial to test this novel re-completion concept was carried out in a gas field offshore Sarawak in December 2001. Expected benefit of a re-completion to solid expandable tubulars is a 40-50% increase in well deliverability from prolific reservoirs previously tubing constrained.If proven successful, this novel recompletion design will be extended to other tubing constrained gas wells in the area.The paper will present the results of this field trial, which is the first of its kind in the world. Details encompassing the conceptual solid expandable completion design, modifications and improvisation required for a SET gas well workover, the SET installation sequence and results from the trial will be presented.
In recent years, the deployment of intelligent completion technology has increased as has the range and functionality of the systems available. The focus has been on developing intelligent completions that will allow a greater degree of controlling reservoir inflow. Improvements in the methods that could be used to model the values of these complex completions have in general lagged behind. In this paper, a phased process for evaluating the productivity benefit offered by an intelligent completion system for a multi-layered, shallow gas reservoir system is described in detail. To start the process, an intelligent completion system was selected that was compatible with the well architecture and would provide maximum flow control capability (infinitely variable choke). Analytical methods where then used to conduct a screening exercise in order to evaluate the production benefit this high-end intelligent completion could offer. This screening exercise provided a fuller understanding of the hydraulic interactions occurring within the wellbore. As such, it was possible to tailor the level of intelligent completion functionality to the production benefits derived. A detailed study was then carried out using dynamic 3D-simulation modelling, which incorporated the selected intelligent completion components as a part of the reservoir simulation. This phased approach helped in determining the optimum intelligent completion configuration taking into account the time related reservoir performance changes. Introduction Intuitively, a completion that can be reconfigured from surface in response to changes in reservoir performance should be the preferred choice over a conventional well completion. However, the complexity of the technology involved in intelligent completions results in higher costs compared to conventionally completed wells. Thus, the decision to install an intelligent completion system in place of a conventional completion is dependent on demonstrating that sufficient economic benefit can be created. Economic benefit can be derived through reduced intervention costs and reduced well count as well as through production related gains. Potential intervention and well-cost savings are, in general, the most readily quantifiable. However, determination of production gains is less easily quantified. For such determinations, it is necessary to have the ability to predict the production performance improvement related to the intelligent completion system. In comparison with performance predictions for conventionally completed wells, the production forecast must include the reaction of the intelligent completion to the changing conditions within the reservoir e.g. gas/water movement and pressure changes. The precursor to any intelligent completion evaluation is the ability of the engineer to perform a realistic production forecast from a reservoir model, which incorporates all the heterogeneities and uncertainties associated with the reservoir. Such reservoir models should also include the intelligent completion system with all its relevant components. There should be the flexibility to model the changes in intelligent completion system configuration (choke position) that can be implemented in response to changing reservoir behaviour. In this paper, the application of this evaluation process is described in detail for the potential deployment of an intelligent completion system in a shallow clastics gas field operated by Shell Sarawak. The aim of this study was to identify an optimum intelligent well configuration for this field development and make realistic predictions for the resulting improvement in production performance.
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