Read Technology Update: New Landing String Technology Developed for Aggressive Wells text version

New Landing String Technology Developed for Aggressive Wells

Statoil's Åsgard project, an offshore giant located in the turbulent Norwegian Sea, consists of sandstone reservoirs of differing physical properties, some of which require aggressive interventions to stimulate production. When harsh conditions threatened to compromise the integrity of the project's landing string (LS) technology, originally developed for subsea drill stem (DST) testing, Expro augmented its design to create a dual-purpose string capable of operating in aggressive environments in both DST and completion intervention modes. Åsgard's three fields--Midgard, Smørbukk South, and Smørbukk--presented a number of challenges associated with their production. Smørbukk, the most demanding of the three with regard to equipment technology and well stimulation, is a high-temperature field of faulted and inhomogeneous reservoirs. Nearly all of Smørbukk's wells require numerous perforating and logging runs to optimize productivity, including hydraulic fracturing. During cleanup flow period, usually lasting a few days, the well produces drilling fluids, formation sands, and perforating debris. The most aggressive conditions follow hydraulic fracturing, with several tons of debris being produced. Developed specifically for Åsgard to withstand its exceptionally harsh well conditions, Expro's new LS assembly is qualified to operate with an external pressure of 5000 psig, or in water operating depths of more than 10,000 ft. The 6.75-in. frac string system consists of the following components (Fig. 1). Lubricator Valve (LV). The valve establishes a "fail as is" (i.e., in the event of the loss of the umbilicator, the valve remains in its current position) barrier at a predetermined position-- high or deepset--within the LS riser. It is capable of maintaining pressure control, while simultaneously allowing the deployment of tool strings in and out of the well. Retainer Valve (RV). This valve minimizes the time taken to effect an emergency disconnection of the rig from the well by performing the following sequential operation: first, containing the riser inventory by means of a "fail as is" operable barrier; second, displacing the trapped inventory between the RV and primary barrier; and finally, allowing the activation of the disconnect package. Shear Sub. This device is a tubular that contains pressure, accommodates externally applied tensile and axial loads,

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and most importantly, has a section that is capable of being sheared by the blowout preventer (BOP) shear rams in the event that all other redundancies have failed. Subsea Test Tree (SSTT). This is the principal well control device and, as such, many of its functions are safety critical. It provides a dual independent "failsafe closed" barrier facilitating well control in the event of a controlled or emergency disconnection of the rig from the well, without requiring the BOP to shear off. High Integrity Ball Valve. At the heart of the frac string is an improved ball valve, an innovative solution to the majority of technical challenges associated with an aggressive environment. Commonly used within the oilfield as isolation devices, the industry recognizes two basic types of ball valves--the trunnion mounted system and the floating ball system. The objective of the new valve was to minimize the disadvantages while maximizing the advantages of each of these systems with respect to rotation reliability and sealing force. The ball element is housed in a cage that surrounds the ball to prevent passage of debris from the bore to the valve mechanics. The ball element and valve seat have a laminate hard face coating that increases reliability, protecting the critical sealing surfaces from the effects of aggressive particulate. Complementary to the ball valve is an operating system that automatically redirects reaction-load paths by allowing a very slight movement of a ball valve retaining mechanism. This mechanism allows the ball element to be unloaded off but remain in contact with the valve seat during rotation, so as to prevent debris ingress between the ball and the valve seat, and to instantaneously reload onto the valve seat upon the event of closure. Automatic load redistribution occurs as a result of three differing levels of mechanical spring force, each interacting with one another at predetermined intervals throughout the valve cycle. Preliminary Testing. The Frac/LS testing program began in July 1998 and was completed in February 2000. Since the main demand on the LS technology was to operate in aggressive environments, testing attempted to mimic the major contributing factors that would cause the system to fail during fracturing and

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Te c h n o l o g y U p d a t e

Fig. 1--Configuration of Expro's new landing string assembly developed for Statoil's Åsgard project.

Problem. Seventy-five percent of perforating lost time is associated with incomplete or incorrect job design, planning, and preparation. In-depth investigation revealed an opportunity to reduce preventable perforating failures and increase service quality. Together with the business unit, a business case was developed to identify the contributing factors and the proposed value of knowledge management. Approach. Five individuals from the business unit were identified to design and develop the KM solution under the tutelage and support of the core KM team. These resources were dedicated to the project full-time for three months and were temporarily collocated with the KM group for the duration of the project. To ensure successful integration of the KM solution into the daily work processes of its target users, a detailed assessment of community needs was performed using tools such as knowledge maps and user surveys. In addition, it was verified that the end user was adequately represented. During the design of the KM solution, clear measures that reflected the business case were developed. These ranged from key business indicators and service quality ratings to measures of learning and KM community activity. The necessary data was compiled to establish baselines. Monthly, quarterly, and 12-month goals were then set. Upon deployment, early and consistent monitoring of these metrics quickly identified several key opportunities. It became apparent that the scope of the initial project was too small. In addition, no dedicated knowledge resources had been assigned to support the KM solution. Expansion and enrichment of the KM solution immediately ensued. The scope was properly redefined and an individual was appointed as a Knowledge Broker--a fulltime position dedicated to the facilitation and support of the KM solution. Several individuals were also appointed to act as Local Knowledge Champions, building the community and championing knowledge management in their local geographic areas. A global Knowledge Champion, who sets the strategic and tactical direction, is responsible for the entire solution. The appointment of knowledge resources was both instrumental and essential in developing business ownership and executing the necessary change management strategies. With the focus on building a strong community, these resources were used to effect a culture change and invigorate the social network. Results. Six months after initial deployment, the KM community is thriving and continually expanding on a global basis. Measurements indicate a threefold boost in collaboration activity and a 35% reduction in lost time failure hours. Supplementing these are anecdotal success stories, reported daily, which reflect the value of knowledge management. Examples include near-real-time warnings of potential issues and the identification of new markets.

Conclusion Knowledge management has numerous definitions, applications, and approaches. The strategy presented here employs the use of corporate vision, business justification, business ownership, community focus, workflow integration, balanced measurement, and knowledge resources to maneuver through the complexities of knowledge manJPT agement and deliver its promises.

Michael Behounek, SPE, was appointed director of Knowledge Management for Halliburton's Energy Services Group in 2001 and is responsible for its strategic planning, Behounek Martinez project development, and deployment. Prior to his current position, he was the Global Quality Manager for the Energy Services Group. He has a BS in mechanical engineering from the U. of Michigan and a MBA from Pepperdine U. Mary Rose Martinez, Knowledge Management Specialist, is part of the core team responsible for the implementation of KM within Halliburton's Energy Service Group. She has a MS in computer science from Rice U. and a BA in computer science from the U. of St. Thomas, Houston.

Technology Update

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post-fracturing cleanup operations. Testing was divided into two discrete stages--static and dynamic-- using a variety of contamination concentrations. Both trials were successful, with the most demanding test trials exceeding the anticipated level that would be experienced offshore. Field Trials. Statoil field tested two LV assemblies during 1999. Both valves continue to perform faultlessly in various Statoil projects, achieving a total of 30 deployments as of March 2002. In March 2000, two complete LS systems were commissioned in Åsgard. Both strings have completed 21 deployments with no attributed rig downtime. Expro has recently commissioned another four LS systems, two of which are being used in the British North Sea sector by ExxonMobil. The remaining two were deployed by Shell during November 2001 as part of an extended well test at a water depth of 3,400 ft. As of March 2002, production from these two strings has JPT reached more than 1 million bbl. Information provided by Neil A. Brown, Expro North Sea Ltd., and Lorents Reinås, Statoil.

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