Flow Control Devices (FCDs) have demonstrated significant potential for improving recovery in Steam Assisted Gravity Drainage (SAGD) production wells. One initial hypothesis was that steam breakthrough was delayed because the FCDs better homogenized injection and production by equalizing flow and compensating for pressure changes along the wellbore. However, in many cases, the field results were far greater than such an approach would have justified. The actual physics for this process are unclear, and not demonstrated in literature. Upon review of field data published by ConocoPhillips, the possibility of a steam blocking effect was proposed (Stalder, 2012), although the physical basis for this effect was not explored. This paper proposes an updated hypothesis to explain this effect, presents preliminary data to support the assumption, and introduces a new apparatus and methodology to characterize FCDs for SAGD applications. The traditional approach to steam control states that steam flashing at the producer should be avoided, as it will eventually lead to a completion failure. Alternatively, the proposed hypothesis contemplates using steam flashing at the producer to regulate flow in various segments of the completion, thus better enforcing conformance. The physics of this process will primarily be described analytically; however, this effect was also observed qualitatively in a small-scale experiment where water was flashed across an orifice. In order to design SAGD completions that leverage FCDs (and this effect), it was necessary to accurately characterize different FCDs under these challenging multiphase flow conditions. Since vendors use a variety of approaches when designing their FCDs, a protocol was developed to create a characterization procedure which was independent of the underlying FCD design and architecture, resulting in a direct comparison of the overall performance of each FCD. Part of this protocol required the construction of a new, high temperature multiphase flow loop capable of subjecting FCDs to representative SAGD operating conditions. Through fine control of the relevant test parameters, accurate performance measurements can be obtained for each FCD. This paper will present some information regarding the design and specifications of this new flow loop, as well as impart some of the lessons learned from its commissioning and initial operation.
High rate injection or production of fluids with sand particles places wellhead components and downhole assemblies at risk of erosion damage. Depending on the severity and location of the material loss, this may pose a significant well loss or blowout hazard. For this reason, assessment and mitigation of erosion can be critical for such applications.In this work, Computational Fluid Dynamics (CFD) was used in conjunction with erosion models to assess the erosion damage characteristics associated with the operating conditions and equipment for a high-rate, shale gas reservoir fracturing application. The work was based on the severe erosion damage experienced by EnCana as a result of high rate hydraulic fracturing operations performed in horizontal shale gas wells at their Horn River, BC field development. Material losses were observed within the wellhead equipment as well as in the LTC couplings of the production casing string near surface in several wells. CFD models were developed for the existing wellhead and wellbore geometries and used to simulate a range of hydraulic fracture operating conditions in an effort to predict the locations and degree of material loss in the components in each case. The models were calibrated with caliper log data and measurements taken from casing samples retrieved from several wells. The analyses suggested that well head system modifications, such as tubing head spool changes and use of spacer spools, could be effective in substantially reducing material losses in the tubular connections. In addition, sensitivity analyses were performed for different wellhead configurations and variations in the hydraulic fracturing parameters to determine the factors that likely had the most influence on the connection material losses. The results served to demonstrate that it is possible to use CFD with erosion models as predictive tools to identify locations of severe erosion in completion systems, and, when calibration data is available, to quantify the amount of material loss in wellhead and downhole components. This information can aid in designing optimum completions systems, and in defining operating conditions which can reduce the risk of equipment failure, potential blow-outs, and associated safety and environmental hazards.
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