fax 01-972-952-9435.References at the end of the paper. AbstractIn 1997, Statoil and Halliburton Energy Services, Inc. began jointly evaluating technologies that could be used to develop a revolutionary coiled-tubing and well-intervention system. This system, which will be deployed initially in the Norwegian sector of the North Sea, sets a new standard for drilling with conventional drilling rigs or coiled-tubing drilling units. The advanced well-construction system consists of a digitally controlled and automated coiled-tubing drilling system that uses a new advanced composite coiled tubing (ACCT) with embedded wires and a tractor-driven bottomhole assembly (BHA). This system enables the geological steering of complex, extended-reach wellpaths that were not previously achievable.This paper discusses a joint development project in which the operator and the service company worked together to design a fit-for-purpose system that met Norways stringent health, safety, and environment (HSE) requirements. The systems three major subsystems are discussed: the digitally controlled and automated surface equipment, the 2 7 /8-in. ACCT with embedded wires, and the drilling and intervention BHA. Test results from qualification and pilot wells are also included.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractRecord high prices for oil and gas have increased the opportunity for producers to maximize the value of their assets. Under current market conditions, reservoirs previously considered marginal or even noneconomic can yield an acceptable return on investment and are increasingly considered for well completion. Many are lower-permeability formations that require fracture stimulation during the completion phase to deliver economic rates. In the latter part of 2004, a new stimulation technique was introduced to the industry, providing well operators a method to achieve multiple-zone fracture stimulation while controlling stimulation costs. By mid-2005, this new process had been evaluated by several operators in the US as well as Canada and Australia with very positive results.This new process offers the opportunity to perforate and stimulate multiple pay zones with a single well intervention, often within a single day. The technique employs a hydraulic jetting assembly on coiled tubing (CT) to erode perforations, immediately followed by pumping a fracture-stimulation treatment through the annulus between CT and casing. At the completion of the first fracturing stage, small-volume, highproppant-concentration slurry is left in the wellbore to provide isolation of the just-stimulated zone from subsequent targets. In some applications, a wellbore screenout may also be induced to improve the temporary isolation of this zone. This sequence (perforate, stimulate, isolate) is repeated until all desired zones have been treated. Following the final stimulation stage, the well is cleaned out with CT and turned over to production. If needed, N 2 gas can be pumped through the CT to kick-off the return flow.This paper describes the operational aspects, advantages, and limitations of using this new multistage perforating and fracturing technique with example field applications.
This case-history paper presents an account of the application of expandable (swelling) packers and a hydrajet perforating stimulation technique to perform a cementless completion and hydraulic stimulation in a 350o F, openhole horizontal well of 15,700 ft total vertical depth (TVD). Resulting production was more than three times that of an offset vertical well. The first Wilcox Meek 2 well in the Brazos Bell Prospect Area was drilled and completed to test the effectiveness of horizontal well technology in tight-sand formations. This paper presents the cementless completion process and explores the effectiveness of horizontal-well technology in tight sands by comparing initial horizontal-well production rates to those of offset vertical wells. The well, which was the first horizontal Wilcox in the area and probably the deepest horizontal well completion for a sandstone reservoir in South Texas, used a 5 ½-in. / 3 ½-in combination string as a production string. The 3 ½-in casing was run in the openhole horizontal lateral section and extended into the 7 5/8-in liner casing. It employed five swellable packers, strategically placed on the string to facilitate isolation for optimum stimulation results. An additional swellable packer, larger than the previous five, was run on the top of the 3 ½-in casing string and was placed inside the 7 5/8-in casing to help ensure complete isolation of the annulus. The swelling packers were activated over an 18-day period by hydrocarbons present in the oil-based mud (OBM) in the annulus. Following packer activation, four fracture-stimulation operations were conducted in a non-cemented hole using a unique fracturing technique that incorporates hydrajet perforating with coiled tubing (CT). This technique allows formultiple stimulation treatments to be performed in series without the CT being removed from the hole,larger stimulation stages, andmaximum surface-area exposure to the fracture pressure without formation damage caused by cement. Introduction The Wilcox formation is composed of gas-producing sandstone. High-temperature, high-pressure formations such as the Wilcox have reported temperatures of 350°F and above with typical geo-pressured conditions found below 12,000 ft in the onshore Texas Gulf Coast area. Zones of interest are located at ~15,500 to 15,700 ft TVD with porosities ranging from ~26 to 30%, and permeability of 0.001 md. The purpose of drilling the Foster Farms Deep #1-H well was to test a 2,000-ft horizontal section of the Wilcox Meek 2 formation in the Brazos Belle prospect area of Southeast Texas. Vertical wells previously drilled in this area were successfully completed and fractured stimulated in the Meek 2. Over time, these wells have exhibited stabilized production of less than 1 MMcf/D of gas after initial flow rates that exceeded 3 MMcf/D. While these wells are considered economical, a decision was made to use the latest technology in horizontal drilling and completion in an effort to enhance the productivity of Meek 2 wells drilled in the Brazos Belle area. Drilling Operation Since this was the first horizontal Wilcox well in the area and the deepest horizontal well drilled to the Wilcox in South Texas, the drilling program was modified to aid the successful drilling and completion of the 2,000 ft lateral section. The geometry of the borehole was designed to drill in the direction of the least horizontal stress to maximize wellbore stability, intercept most of the natural fractures (if any) in the reservoir, and obtain the best permeability of the producing formation while trying to minimize the tortuosity during the completion.
Finding sufficient information to help drive better decisions is not an issue in the oil and gas industry—this industry is one of the most data-intensive in the world. The challenge is interpreting all the data we possess. Furthermore, various disciplines or departments hold critical information that might be useful to others, but not often can it be shared because of technology or process issues or simply because it may not be known that others could make decisions with it. How can asset teams leverage all the information they possess to make better decisions and improve production and recovery rates? In particular, what can be done to bring together the vast amount of information that both the geological and geophysical (G&G) and stimulation worlds have? What is needed is a solution that allows stimulation data to be integrated with geological and geophysical data to understand how the reservoir will fracture and respond to stimulation treatment. This solution will allow for better decisions to be made about how overall reservoir production can be improved: microseismic events can be viewed in context of G&G data to refine stimulation treatments; attributes of seismic information, such as curvatures, can be used to understand how the formation might fracture and help drive well placement and perforation strategies; experts who do not traditionally weigh in on fracture design (i.e., geophysicists) can now have a seat at the table to help improve stimulation placement and treatment design for improving stimulation effectiveness. In new plays, like some of the unconventional shale gas plays, little is often known initially about how the formation will react to a given stimulation treatment. In such cases, a trial-and-error approach is often used; however, a strategy that might have been successful in an older shale play might not be successful in a new shale play, as with traditional sand reservoirs. The ability to use seismic and other data, as well as expertise from other disciplines, might greatly enhance overall success in new areas. Introduction Information is critical to making decisions, but how do we get all of the information we need into the hands of the right people at the right time? How can we create a collaboration environment in which correlations and trends can be visualized and verified? And, more importantly, how do we create a workflow that allows us to continuously optimize results quickly, even in real-time? Nearly every service company and operator has an initiative to drive efficiency by better integrating data and disciplines. Many are steadily making improvements in data access, and this paper presents a software tool for visualizing microseismic events in the context of the geological and geophysical background or geomechanical model of the formation and a workflow to optimize stimulation performance. These steps bring together geoscientists and fracture engineers so that they can make decisions collaboratively and improve the return on stimulation investment. Why, and where, is this important? In tight gas and shale plays, production of a well is dependent on the effectiveness of hydraulic fracture treatments. It is commonly said: " If we do not fracture it, we do not produce it.?? The question then becomes, beyond waiting to realize production, how does an operator know if a formation as been effectively stimulated? Microseismic fracture mapping allows us to visualize the physical location in the formation that was treated, or at least disturbed by the treatment. Fracture mapping removes the guesswork about whether the treatment stayed in zone until actual production numbers are available. Reference 22 provides examples of the benefits of integrating microseismic mapping in the Overton Field of East Texas.
Historically well drilling operations have been based exclusively on steel pipe. Recently a drilling system that combines composite coiled tubing technology and hydraulic workover technology has been introduced. This paper examines the operating experience for the system and its implications for the future.By using composite pipe with embedded conductors, the system achieved uninterrupted real-time two-way communication with the downhole tools. This allowed a stepchange improvement in the knowledge of dynamic wellbore conditions and in the control over downhole systems. New procedures were developed to assimilate and use this increased functionality. These procedures include both geosteering and real-time system diagnostics from remote locations.Incorporating a hydraulic workover (HWO) jacking system as an integral part of the drilling unit also expanded the operating envelope and functionality of the entire drilling system. This revolutionary full-system development encountered numerous challenges, many of which are related to the unique properties of composite pipe in difficult hole conditions. The technological solutions to these challenges are examined in depth.
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