Halliburton entered the picture with its technology commercially in 1993 and employed its first Single-Trip Multizone (STMZ) system and Single- Trip Dual Zone (STDZ) system in the South China Sea. The company’s Otis Engineering subsidiary, through its sand control tools group, began developing the STMZ system to meet the requirements of the China project. Tommy Grigsby, Halliburton’s sand control tools product manager, notes the STMZ tool has over 300 installations to its credit and is still being run in China, Indonesia, and Italy.
These second-generation systems could handle acid pre-packing and viscous gravel packing to provide zonal isolation from the annulus above and improved operational efficiency over earlier systems, Grigsby says. Like the first generation, the second generation used dual concentric strings to facilitate gravel placement and return flow. ‘The dual concentric string design remains the limiting factor,’ Grigsby says. ‘As completion interval lengths increased, the reduced ID of the inner string and the restricted flow area of concentric return path resulted in increased fluid friction during pumping and reversing.’
He notes this created issues like limited pump rates, higher surface pump pressure and sand out pressures required the upgrade of all system components to handle the higher pressure.
Halliburton’s next version of the tool – fourth generation – is the Enhanced Single-Trip Multizone (ESTMZ) system, designed to meet requirements for an operator’s Lower Tertiary acreage in the Gulf of Mexico (OE September 2009). This generation, Grigsby says, have 10,000psi differential pressure rating of all downhole hardware, single concentric string extending from the hydraulic setting tool down to the lower service seal assembly containing the gravel packing ports, isolation of each zone pre- and post-packing, are designed for fracking, and do not require lower washpipe except to space shifting tools for the bottom circulating sleeve.
Halliburton was due to complete its first Lower Tertiary well early last year with the ESTMZ system; however, the operator pushed installation back to 1Q 2010. Halliburton carried out system integration tests (SIT) in late 2007 for the project. Two trial wells in Colorado followed to validate the equipment, pick-up and running procedures, then in 2009 a third SIT was carried out to validate additional system components and provide more hands-on training experience.
Three ESTMZ installations are scheduled in Southeast Asia this year.
Grigsby notes two fourth generation systems are available today. These systems were designed to meet specific project requirements that represent opposite ends of the completion spectrum. ‘[BJ’s] MST was designed to accommodate gravel packing and low-rate fracking for a gas field development, while [Halliburton’s] ESTMZ system was designed for aggressive frac packing in the ultra deep Lower Tertiary. In time, these systems will be optimized and will evolve for multiple market segments,’ he says.
Grigsby believes the technology could go in several directions as it evolves. One of those options is to use it in an open hole environment, a possibility being planned as a contingency if a casing string fails to reach the total well depth, he says. Secondly, he says, it may be possible to incorporate interval control valves as part of the screen assembly. ‘Ideally they will be operated remotely without the use of control lines that are currently required,’ Grigsby adds.
‘This will be a tough task due to the requirement to maximize equipment ID and minimize equipment OD.’ OE
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