Exploration and Production Technologies

Advanced Monobore Concept CFEX Self-Expanding Tubular Technology


The goals of this project are to prove technical, economic, and manufacturing concepts for innovative, self-expanding casing technology for use in monodiameter wells and to successfully deploy a small section of the casing in a demonstration well. The project is part of DOE’s Microhole Technology Initiative.

Dynamic Tubular Systems, Inc., Houston, TX
Confluent Filtration Systems, Houston, TX 
AMET, Inc., Rexburg, ID

In 2003, after earlier exploratory research conducted by Los Alamos National Laboratory, DOE’s Office of Fossil Energy began placing added emphasis on microhole technology. DOE envisions microholes with diameters with diameters of less than 3½-inches. To accommodate these smaller hole sizes, a whole new suite of miniaturized sensors and other downhole equipment is needed. DOE, through NETL, launched the Microhole Technology Initiative in April 2005 and made the first round of project awards in June 2004.

Microhole technology holds great promise for economically recovering a sizeable portion of the estimated remaining, bypassed shallow (less than 5,000 ft subsurface) resource in the United States. DOE estimates this targeted shallow resource at more than 200 billion barrels of oil. Recovering just 10 percent of this volume would equal 10 years of OPEC oil imports at current rates.

Because of its ability to drill wells in much less time, microhole technology offers the potential to reduce drilling costs by at least a third or more in exploratory drilling. And the smaller-diameter holes also mean a smaller “footprint” and a reduction in drilling wastes of at least 20 percent, resulting in a reduced environmental impact. Using a smaller, more readily deployable microhole coiled tubing rig in tandem with lower costs for handling a smaller waste stream could reduce overall field development costs by 50 percent or more when compared with conventional wells.

Applications and benefits of this self-expanding casing technology for monodiameter wells include reduced costs and environmental impacts in drilling and production operations in other areas, including ultradeepwater and unconventional resources such as tight gas and oil shale resources. Further applications include uses in environmental, civil, and minerals areas.

The project has demonstrated an operationally efficient, reliable, and economically viable expandable well casings for use in both microhole and conventional drilling operations. Results to date show mechanical properties and manufacturing viability exceeding original project expectations. Preliminary testing of the technology shows technical performance as an expandable to be comparable to standard tubulars. Two phases of manufacturing analysis showed costs competitive on the same order of standard tubulars. Applications and benefits of this technology will also include drilling and production operations in other areas including, ultradeepwater and unconventional resources, such as tight-gas and oil shale resources. Further applications include uses in environmental, civil, and minerals fields.

The expandable casing being developed in this project consists of various types of elastically biased members which, when compressed, temporarily reduce the diameter of the casing. The reduced size is held in place by temporary bonds made between the compressed-member surfaces. Once inserted into the well-bore, the stabilizing bonds are removed by chemical or mechanical activity and the casing recovers towards its original, oversized dimensions.

Major Project Accomplishments to Date 
Development of the new technological concept comprised the initial phase of the project. The conceptual phase elucidated several design candidates. The optimal casing geometry was taken forward, based on detailed qualitative and numerical analyses. Design optimization through rigorous analysis was the primary engineering phase accomplishment. The final technical phase, or manufacturing phase, work successfully fabricated and tested several short-length prototypes. Construction of the non-standard length field prototype required significant manufacturing tooling and process development in order to perform an in-hole demonstration..The field prototype delivery and verification system were successfully constructed and deployed. A demonstration well was constructed by the contractor , which acted to demonstrate an actual monobore type operation by expanding a related NETL technology project underneath the monobore casing..

The project team first established industry-user definitions, technical specifications, and performance measures for a new technological area. These parameters represent the technology’s design criteria. Fundamental literature research supported the concept development program. Based on newly defined performance criteria, a qualitative-brainstorming program was conducted to develop expansive-tubular system concepts and to evaluate prospective design geometries. The brainstorming program was assisted by a major research institute. Over 100 conceptual approaches were generated and evaluated. The approaches were grouped into approximately ten geometry categories. A prioritized performance criterion-compliance process, augmented by basic engineering calculations, served to rank the merit of the geometric concepts. Two excellent-rated design candidates resulted from the process.

Analytical design optimization was the major middle-phase accomplishment. This refinement work to the qualified design concepts involved the use of progressively rigorous computer analytical methods and basic physical testing. These methods included design by analysis routines, finite element analysis, and 3-D geometry construction for computer-aided machining purposes. Successful fundamental physical testing efforts were also accomplished. The results of the preliminary physical tests showed all basic properties occurring equal to or slightly higher than engineering predictions. Advanced engineering work concluded feasibility of conventional diameter operating pressure ratings in excess 10,000-psi for the technology – a capability well beyond both MHT program requirements and standard expandables industry capabilities.

A detailed, two-phase study of the technical and economic manufacturing requirements was successfully conducted, covering all known design details. Already accounting for all estimable manufacturing costs, the analytical conclusion for both feasibility and cost basis as is very favorable at approximately 2.5X over standard, non-expanding tubulars. The conclusion of the study is that manufacturing costs for the new expandable are less than purchase costs for conventional expandables.

Prototype construction, detailed laboratory testing, and field demonstration activities comprised the last technical phase of the project. In this manufacturing and testing phase, laboratory through field scale prototypes were fabricated and pre-tested for the intended expansion performance in the field. The development of major manufacturing tooling and components for the field-length prototype have also resulted in novel methods for tubular expansion which avoid common reliability issues in the conventional industry.

Current Status (January 2009)
All technical deliverables were successfully delivered according to the project schedule and the project is complete. Technology transfer work has been conducted throughout the project and has resulted in receipt of multiple RFP’s for related commercialization interest by a major international producer. The final project report is listed below under "Additional Information".

This project was selected in response to DOE’s Oil Exploration and Production solicitation DE-FC26-05NT15480, August 2, 2004.

Project Start: February 2, 2005
Project End: August 31, 2007

Anticipated DOE Contribution: $975,644
Performer Contribution: $270,600 (22% of total)

Contact Information
NETL - Virginia Weyland (virginia.weyland@netl.doe.gov or 918-699-2041)
Dynamic Tubular Systems, Inc. - Jeffery Spray (jaspray@earthlink.net or 281-597-8784)

Additional Information

Final Project Report [PDF-1.82]

Spray, Jeffery A., “High-Ratio, Elastic Region Tubular Expansion,” Hart E&P Magazine, August 2006.

Split-tube casing system selected for development and field demonstration, late 2006/early 2007.

An artist's cutaway rendering of a self-expanding sandscreen.