Growing energy demand is leading the industry to re-evaluate resources found in challenging conditions such as unconventional gas formations, re-entry wells, and/or low producing wells. Cost-effective development of these resources depends on strategic application of advancing production solution technologies. To enhance production and improve recovery processes, more efficient perforating and fracturing methods have evolved along with advancements in wellbore production hardware via use of solid expandable tubulars or combinations of solid expandable and conventional tubulars.
Expandable technology applied as a completion/production string facilitates increased fracturing rates, resulting in improved conductivity and enhanced hydrocarbon production. Expandable tubulars can be used in re-entry wells to isolate old perforations, allowing for new zones or new sections within zones to be perforated and stimulated. Either a combination tubular cladding system or a solid expandable system can provide an integral component in new wells or re-entry wells where low-permeability reservoirs, such as those characteristic of unconventional gas formations, require isolation and separation for selective or pinpoint hydraulic fracturing or re-fracturing.
Although successful stimulation is routinely attained from hydraulic fracturing, ancillary downhole tools such as conventional completion equipment often compromise results by restricting flow and affecting pressure performance. Solid expandable systems can optimize the fracturing parameters by maintaining larger diameters and providing seals for selective multi-zone or zonal isolation purposes. These production systems can consist of either solid expandable tubulars or expandable sealing sections combined with conventional tubulars using premium connections, thus providing a superior completion solution.
This paper will explain how solid expandable tubulars can be used to facilitate first-time fracturing, re-fracturing, and multi-zone fracturing, refurbishing older wells, and attaining large-diameter production/reservoir conduits. Integration and system development of this technology will be discussed. Case histories will be cited to illustrate the effectiveness of solid expandable systems in enhanced production and fracturing applications.
A large percentage of the world's future energy demands will be fulfilled by unconventional natural gases that include tight gas, coalbed methane (CBM), shale gas, deep earth gas, geo-pressured gas, and methane hydrates. Unconventional gas reservoirs require the formation to be fractured by hydraulic means to improve the formation productivity by providing a conductive path and joining the existing fractures and cleats in the reservoir. (Zahid 2007)
Estimates of shale gas in the US range from 500 to 1,000 Tcf, while the Gas Technology Institute calculates ~780 Tcf. The US Energy Information Administration estimates that US shales contain 55.42 Tcf in recoverable gas. Shale plays with potential occur across the United States from southern California through the Rocky Mountains, across the Midwest into the Michigan, Illinois, and Appalachian basins in the east and as far south as the Black Warrior Basin in Alabama. (Lyle 2007)
Continual advancement/improvement in oil and gas exploration and exploitation programs and better reservoir management has led the industry in maximizing recovery from mature producing fields and new oil discoveries. An influential aspect of economic viability is decreasing lifting cost by introducing new technologies that reduce expenditures through improved exploration and appraisal techniques and better drilling and completion practices. These technologies and practices have also helped accelerate production from mature fields (brownfields), new gas plays, deep and ultra-deep wells, and highly complex reservoirs. Brownfields, defined as mature fields in a state of declining production or reaching the end of their productive lives, are generally more than 30 years old and account for 67 to 72 percent of world's production. (Economides 2002)