Better asset management, fewer well interventions
targets of emerging, wholistic completions
Rick Von Flatern
- Bringing all downhole and surface control and monitoring functions under a single system is the ultimate goal of smart wells and intelligent completions.
One of the ironies of offshore operations is that secondary payzones, often needed to make projects economical, also have the potential to foil them. Accessing secondary zones, especially marginal ones, can require expensive and risky well intervention, which can negate profits if they fail.
In recent years, the dilemma has been exacerbated by a second irony in deepwater - increasingly complex wellbores, designed to save drilling and completion costs, also raise both the cost and risk of intervention. Highly deviated and horizontal wellbores and multilateral completions, while offering more formation access for less investment, have also complicated production management.
Two alliances, comprised of four of the industry's largest service companies, have been formed to address the twin problems of well interventions and inefficient production management. Halliburton has formed an alliance with Petroleum Engineering Services and Schlumberger has formed one with Baker Oil Tools to develop methods and tools to complete wells with downhole, permanent data-gathering and production control technology.
Much (some say all) of the necessary technology - sliding sleeves, pressure and temperature gauges, computers and SCADA (supervisory control and data acquisition) - is already in place. Others, such as downhole multiphase flow meters and downhole chokes, downhole separation and water reinjection need refinements.
This wholistic approach, because of its reliance on data management to bring together the elements of production has been dubbed by the alliances "smart wells" (Halliburton/PES) or "intelligent completions" (Schlumberger/Baker).
These advanced well systems are completed with permanently placed, surface-actuated, production monitoring and control devices. The basic hardware currently is used in conjunction with coiled tubing or wireline and has been for years. The critical work is to free these tools from reliance on well intervention for placement or actuation, to make them a permanent part of the completion string.
Few in the industry expect it to be an overwhelming challenge. Similar technology has been used to set a completion packer and electric power cables have been run alongside tubing at least for as long as electrical submersible pumps have been used.
David White, Schlumberger's business development manager for permanent monitoring control, has stated (Oct. 10, 1996 Amoco newsletter, The Brief) that the first step toward the goal of permanent downhole monitoring devices is to complete the well as a "newly designed, highly reliable permanent reservoir monitoring system." The system, according to White, uses digital electronics sensors capable of surviving years downhole to transmit real-time reservoir data via cable to the surface.
But smart wells are not a single technology nor are they designed to stand alone. They are more accurately a critical link in a system of what Halliburton's Roy Centanni called a real-time asset management system. Speaking at a November seminar in New Orleans on deepwater technology, Centanni, Halliburton's vice president of market development and technology, said he expected implementation of a fully integrated system of monitoring, control, and data management adapted for a specific field to be in operation around the turn of the century.
The immediate challenge for the future of intelligent completions-based, real-time asset management is a seamless crossing of downhole tools and surface technology. The final system, as envisioned by both alliances, will integrate data processing, interpretation, and decision-making across intracompany lines with data bases in forms useful to engineering, geology, finance, and business sectors.
Communication between the well and analyzers and among analyzers is the heart of the system. The goal, in the final analysis, is to improve ultimate recovery efficiency. White says the new technology would "usher in a new era in productivity, characterized by up to 50% recovery of hydrocarbons, as compared to the current industry average of 35%."
Old tools, new applications
Most of the downhole equipment to be used in smart well completions is based on familiar, time-tested technologies. Of particular significance to production management without intervention is zone selection. Sliding sleeves will be used in intelligent completions, just as they have been for years, to shut off or open zones and recently as part of lateral isolation packages. The difference will be in how the sleeves are shifted and when.
Currently, multilateral selection options are limited. High costs of well intervention equipment, equipment mobilization, and lost production time means, particularly in deepwater, the most economic production strategy is to fully deplete a primary lateral before opening others. This minimizes well intervention while assuring that the maximum amount of hydrocarbons are produced eventually.
Simultaneously, producing all laterals is possible only when they are equally pressured or the wells are completed as dual and triple completions in vertical single well bores. The added cost of packers and multiple strings of tubing for isolation, plus the complexity such completions add to well interventions, is often prohibitive.
Return on investment is slowed and reduced by delaying production from a second lateral while depleting a primary one. The intelligent completions opens or closes laterals from the surface at essentially no cost, allowing operators to produce each lateral at its maximum rate and bring more oil to market sooner by shifting between zones as they decline.
Through such precise production management, it is conceivable that in the end all the pressure-equalized laterals can be commingled, effectively lowering the economic limit of each, extending the life of the well, and raising ultimate recovery. All in less time for more return than would be possible should major intervention be involved.
Smart completions may also offer the option of producing all laterals at once through what is essentially production automation. By combining real-time data, decision making computer software, and adjustable flow control devices in each lateral, pressures and flow rates can be equalized allowing all laterals to be produced at once through a single main well bore without fear of crossflow.
Critical to optimal advantage from both sliding sleeves and lateral bore chokes is extremely accurate, real-time downhole data. Bottomhole pressure and temperature instruments have existed for decades, and surface real-time readout for years. But the accuracy of downhole multiphase flow meters is suspect in some quarters, particularly in highly deviated and horizontal wellbores where gravity separation introduces a variable many feel has yet to be adequately addressed.
The most important of the driving forces behind the new petroleum industry prosperity is the refinement of 3D seismic. The recent availability of computers capable of processing the immense amounts of data involved has reshaped the world of exploration by greatly reducing the odds against finding hydrocarbons in new areas and by revealing deposits overlooked in mature fields.
Now production managers are seeking to use what has traditionally been an explorationist tool by adding the fourth dimension of time to seismic data. By taking multiple 3D seismic surveys over producing areas at different times, separated by six months or more, analysts can track fluid movement. Production managers can thus gain insight to such things as trapped oil and gas deposits and location of flood fronts.
It is a powerful weapon, but repetitive surveys are expensive. In the North Sea and elsewhere, some operators have tried to mitigate the costs of surveys by burying seismic streamers in fields where they wish to do a series of these 4-D surveys. Should the results be as positive as is expected, the installation of permanent seismic streamers could easily become another element of smart wells.
Incorporating 4D seismic, original geologists' earth models, and the well history and monitoring capabilities under one supervisory system, will make it possible to do near real-time seismic modeling of producing formations.
Availability to all parties of all real-time data will allow company efforts to be coordinated in a way considered nearly impossible today. Bridging the gap between the equally important realities of the field and the boardroom by different data sets should result in consensus allocations for such things as facilities, transportation, new wells, and pipelines.
A management tool
Oil and gas will be relatively flat price commodities for as far into the future as anyone can see. That, combined with the industry realization that costs have been cut maximally, has led to a culture of efficiency through technology.
As a result, the goal of all research and development has become better asset management to increase company profits by ensuring the greatest possible return from each capital and operating expenditure.
In that context, smart wells and intelligent completions appear simply as the latest step in that direction. It is not so much revolutionary technology as evolutionary process that gathers in a single spot the technical developments coming to the marketplace at an ever accelerating pace.
In his presentation in New Orleans, Centanni presented a list of ways smart wells will help operators maximize their investments. First and second on that list were higher rates per well and reduced well interventions, even as wells become more complex.
Only one of Centanni's items involved cost reduction, the one concluding that fewer well interventions and increased downhole processing translated directly to reduced topside costs. The remaining four positives to be expected from the implementation of smart wells all related to efficiency:
- Reduced time to first oil improves NPV
- Reduced production downtime
- Improved recovery efficiency (over current 35% average)
- Well life cycle asset management.
The very act of naming smart wells and intelligent completions may lead to confusion as to what they are. There appears to be no short answers defining smart wells, intelligent completions, and the alliances pursuing them. They are probably best described as concepts under construction. Certainly adding some uncertainty to the alliances is the fact they are both formed between companies who are competitors in at least some areas. At certain junctures in their lifespan, snags will be inevitable over such things as whose technology will drive the endeavor, or how much proprietary information each company will afford its alliance partner.
Smart wells, intelligent completions, or some facsimile are almost certainly the future of field development. Even the experts most closely watching these developments are loathe to say exactly if the final product will be like the current endeavors, or an expansion or diminishment of what has been proposed. The truth is is evolution, under its own momentum in some ways, and there is not likely any final product to make predictions about.
Copyright 1996 Offshore. All Rights Reserved.