The Application of Flux-Based Sand-Control Guidelines to the Na Kika Deepwater Fields

Abstract

The Na Kika offtake guidelines were developed jointly by Shell and BP using a blending of recent sand control operational methodologies from each company.In this paper, we focus on the use of the bpfluxTM guidelines, which give the maximum safe operating rates for sand control completions, and allow wells with excellent completion quality to produce at twice the rate of wells with lower completion quality. Before the Na Kika field started up, we estimated the completion quality by reviewing 20 different elements of completion design and operations.We used these estimates to set the initial off-take limits for each zone.As the wells started producing, we performed pressure build-ups to measure the actual completion quality (skin), and adjusted the maximum operating rates accordingly. Using this methodology early in field life, we were able to bring the field up to targeted production rates without unnecessarily compromising long-term sand control reliability.As the field matures, we will identify opportunities to extend the production plateau, which will provide an incremental production impact.Finally, later in the field life, we also expect to lower the number of workovers, which will provide an additional cost savings from using these guidelines. Introduction The Na Kika development is in the deepwater Gulf of Mexico (Figure 1), with 12 subsea wells that tie back to a host facility with a production capacity of 130 MBOPD and 500 MMCFD.There are six separate fields that tie-back to the host, which makes this development unique because there is no large field that justified the host on a stand-alone basis. With the exception of the Coulomb field, which was developed after the scope of work in this study, Shell and BP are equal partners in the Na Kika development.All the wells have sand control completions, two are open-hole horizontal wells with gravel packs, and the remaining 8 wells are cased holes with frac packs.As with any deepwater and sub-sea development, long-term reliability of each well is critical to the project success. Over the past few years, sand control well operating guidelines have moved away from drawdown based limits and are now based on velocities at various locations in the completion.In particular, two recent works both offer powerful new methods for safely operating sand control completions.Wong et al[1] discusses two velocity limits; one is the perforation velocity at the casing inside diameter, which that leads to destabilization of the annular pack.The second is the velocity at the surface of the screen and causes screen erosion failure.They also present a surveillance tool methodology to monitor well clean-up during the start-up portion of a well's life.

A New Methodology To Safely Produce Sand-Controlled Wells With Increasing Skin

“…The authors used the new methodology to calculate a new area open to fl ow by accounting for the skin increase. First, the original pressure-transient analysis results were used to history match a mechanical skin using nodal analysis with an assumed perforation effi ciency of 35%, which is consistent with company studies and reports for sand-prone formations, published internally Keck et al 2005). The well is installed with downhole pressure gauges that have failed recently.…”

“…Apart from the regular surveillance such as pressure-transient analysis, nodal analysis, and production testing, the asset is also using BP's flux-based approach (Tiffin et al 2003;Keck et al 2005) along with integrated sand and erosion alarming (Stein et al 2005). The integrated sand and erosion alarming allows the asset engineers to monitor in real time the completion integrity.…”

“…The completion reports for this well had indicated some issues with the original completions job, and thus it received a low completion-quality score. For lower-quality completions, BP's previous work had shown the safe limit to be 30 for the fl ux-based C-factor (Keck et al 2005). We then used nodal analysis to calculate a safe target rate of 33 MMscf/D, which allowed the well to be fl owed close to its fl ux limit (Table 4).…”

“…Our new methodology helps to quantify the risk and convert it into a safe target rate. This paper will also present case studies of oil and gas wells in the Na Kika asset in DW GOM where this methodology was applied successfully.The well completions are monitored with BP's flux-based approach (Tiffin et al 2003;Stein et al 2005;Keck et al 2005). In all cases, the wells experienced increased skin, causing the engineers to choke back the wells.…”

“…The well completions are monitored with BP's flux-based approach (Tiffin et al 2003;Stein et al 2005;Keck et al 2005). In all cases, the wells experienced increased skin, causing the engineers to choke back the wells.…”