The Stones Project is Shell Offshore Inc.'s ("Shell") play opener discovery in the outer Lower Tertiary trend in the Gulf of Mexico ultra-deep water (~9,500 ft. water depth). The initial plan is a phased development, with an FPSO and 8 initial wells for Phase 1, potentially followed by a Phase 2 development after field performance is confirmed. The Stones FPSO is the deepest floating production system in the world. This paper will provide an overview of the Stones project, discussing the challenges that had to be overcome and the innovations that were developed to successfully deliver this ground breaking project.
In over 300 expandable sand screen (ESS®) installations around the world it has proven exceedingly difficult to perform an equitable and rigorous comparison between the open-hole ESS system and an alternative completion technique.In this study, there is a marked apparent difference in completion performance between the systems and this is investigated in more detail in order to compare the techniques on an equal footing. The Mokoko Abana field is situated offshore Cameroon.It is a mature heavy oil field initially developed in the 1980s.The sand is unconsolidated and all wells require sand control from start-up as evidenced by sand production if sand control is not effective.Several different types of sand control have been tried with varying degrees of success.This study is mainly focused on three different completions, all in similar configuration high angle wells in the same reservoir and sand. The first type of completion studied was pre-packed stand alone screens (PPSAS).This showed excellent initial productivity, but was prone to a rapid decline in performance.The decline is attributed to hole collapse, either liberating fines plugging the screen, or creating a low permeability sand/shale mixture in the annular gap. Open hole gravel packs (OHGP) were then used to support the borehole and immobilize any failed sand and fines in the annulus.The OHGP had a somewhat lower initial productivity than the PPSAS but has maintained a higher level of productivity over time. Open hole expandable sand screens (ESS) are the most recent completion option, with the first being installed in Q4 2000. The main reasons for installing ESS were a number of reservoir simulation studies which showed better reserves recovery with a low skin completion, and hence ESS was selected in order to lower the overall skin. As of 2005, the successful ESS wells show a high productivity that has been maintained over four years.An in-depth analysis of the productivity of the PPSAS, OHGP and ESS was undertaken.The analysis was complicated by variation in fluid and sand properties through the reservoir and masked by the different artificial lift methods used.This made an accurate assessment of the performance of each type difficult to achieve.However, even within the uncertainty in the analysis, the ESS completions have a significantly higher productivity and lower skin than the other two completion options. The studies suggest there are production benefits in removing the annular gap. The range of sands controllable with an ESS is wide and supports the Ballard & Beare d[5] criterion.ESS completions correctly applied can be successfully produced with high water cuts and draw-downs in excess of 500psi. Introduction Initial sand control completions in Cameroon were installed in vertical or deviated wells, with the casing cemented, then milled out, and an external gravel pack installed.Many of these have performed well and stood the test of time.
This paper is a Case Study of CO2 reduction (i.e. GHG reduction) in the FPSO Fluminense. The primary objective is to present how a CO2 reduction can be obtained in a typical deepwater production unit in Brazil based on a simple and and zero-cost approach. Additionally, the case study aims to contribute to Brazil's new offshore licensing requirements on GHG management. To address Climate Change the FPSO Fluminese Team set out a list of simple and zero-cost Energy Conservation Measures (EEMs) which have gradually been put in place as of late 2006: (i) Optimization of Gas Turbines -running 2 turbines instead of 3 whenever conditions allow it; (ii) Optimization of Booster Gas Compressors -volume pocket positions are optimized by running one compressor when gas production volumes, including gas lift, drop to a certain level; (iii) Introduction of Cleaning and Washing Routines for Gas Turbines; (iv) Optimization of Flash Gas Compressors -by adjusting the volume pocket position;(v) Seawater injection pump optimization -running only one pump and batch inject on the second, as necessary, to maintain reservoir pressure. In parallel, a review of the FPSO Fluminense GHG inventory was performed in order to create a more accurate database to support the implementation and evaluation of the EEMs. The results show that in 2007, 24% of CO2 reduction (27,5 kt) was achieved in relation to 2006 in the FPSO Fluminese. The CO2 reduction from gas fuel was 17,6% (15,3kt) and flaring was reduced by 62% (11,1kt). Roughly 32% of the CO2 reduction can be attributed to the implementation of the EEMs and 62% to a decline in hydrocarbon production.The main contributions to new the Brazilian requirements on GHG management is the necessity to standardize the GHG inventories for offshore plataforms in order to allow fair comparision of carbon footprints among operators, as well as define correct compensation where required.
The Stones project is an ultra-deepwater development located ~200 miles south of New Orleans in the Walker Ridge ("WR") protraction area of the Gulf of Mexico. This development is part of the frontier Paleogene outboard play in the Lower Tertiary Trend that targets the Upper and Lower Wilcox formations. The initial development (Phase 1) is planned for eight subsea wells directionally drilled from two drill centers with a production manifold located at each drill center. Dual 8″ flow lines will connect the two drill centers with dual 8″ risers connecting the drill centers to a Floating Production Storage and Offloading (FPSO) host. Oil is exported by shuttle tankers with gas exported through the Walker Ridge Gas Gathering System. Mudline pumps will be located at the first drill center. The current field development plan incorporates optimizations based on information gathered during the early execution phase of the project. These optimizations were identified through multi-disciplinary integration with a focus on risk management and best-for-project decision making. This paper highlights the subsurface learnings and associated modifications to the field development plan to mitigate risk, lower costs and increase ultimate recovery.
The Stones asset is an ultra-deepwater development located approximately 200 miles south of New Orleans in ~9500 feet of water . Final investment decision was taken in 2013, with first production achieved in September 2016. This development is part of the frontier Paleogene outboard play in the Lower Tertiary Trend that targets the Upper and Lower Wilcox formations. In early 2014, a change management program was kicked off, originally centered on minimizing well construction risks. This change management program was organically grown, with cost and risk baselines being re-assessed bottoms up, and key opportunities identified. Major improvements were obtained in the areas of minimization of risk and capital investment during the period of 2014 to 2016. Improved risk and cost themes centered on: (a) enhanced trade-off between subsea and well construction complexities; (b) improved subsurface imaging to increase flexibility in well trajectories; (c) deepened integration between completion choices and well designs; (d) technical functionality rationalization; and (e) supply chain improvements. This paper highlights the key change management lessons learned that took place during the Stones project execution resulting in the project meeting the cost promise from project sanction.
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