DOE Digest

Slurry Injection for Managing Drilling Wastes

A May 2003 report by Argonne National Laboratory presents an "Evaluation of Slurry Injection Technology for Management of Drilling Wastes." Slurry injection involves processing solid materials to particles of suitable size and blending them with a fluid to make a slurry that is injected at pressures high enough to continuously fracture the formation receiving the slurry. Injection can be continuous or as a series of smaller-volume intermittent cycles. The report contains a database with full or partial information on 334 injection jobs from around the world (Alaska - 129, Gulf of Mexico - 66).

As the report notes, not all slurry injection jobs have been trouble-free but the reasons behind problems are understood and can be overcome with good design. Results from reviewing many projects reinforce that attractiveness of slurry injection must be determined on a site-specific basis. There are three critical factors that affect cost effectiveness—volume of material to be disposed, the regulatory climate, and the availability of low-cost onshore disposal infrastructure. In many locations, slurry injection compares favorably with conventional drilling waste management practices.

To access the full report, visit DOE's NPTO website (www.npto.doe.gov/
publications/pdfs/SlurryInj
Rep.pdf).

DOE's "Deep Trek" program targets developing "smart" yet economical systems tough enough to withstand the extreme conditions of deep reservoirs. Three recently announced R&D awards follow five earlier awards announced in September 2002 (see prior Tech line www.fe.doe.gov/techline
/tl_deeptrek_2002sel.shtml). DOE is contributing slightly more than $11 million toward the three-year projects. Winning organizations will provide just over $5.5 million.

Honeywell International will develop a suite of high temperature electronic components that can be used for instrumentation in deep gas drilling systems where components can be exposed to temperatures from 250 degrees F to 437 degrees F for prolonged periods. Honeywell, which will conduct the project through its Solid State Electronics Center for Excellence, plans to combine and upgrade some of its existing electronics technology. It will form a Joint Industry Participation group to  

develop system specifications priorto product development. Potential partners in this group include Schlumberger Technology Corporation, Diamond Research, Micropac Industries, and E-Spectrum, as well as other petroleum industry service companies and operators. Total project cost is $8.6 million with DOE providing $6.0 million.

Schlumberger Technology Corporation plans to design and commercialize a high-temperature (approaching 400 degrees F), high-pressure, measurement-while-drilling tool that provides direction, inclination, toolface and gamma ray measurements continuously in real time. The tool will be fully retrievable while the drillstring is downhole, eliminating the need to remove the entire drillstring assembly to retrieve directional equipment. Deep well drilling economics will be improved with extended tool life, plus should it need to be replaced, less time will be lost since the tool will be fully retrievable without pulling the drillstring. Total project cost: $5.9 million with DOE providing $3.8 million.

Cementing Solutions, Inc. (Watters Engineering) proposes a combined effort with Argonne National Laboratory and other industry partners to develop "supercement" with superior pipe and formation-bonding capabilities at depths exceeding 15,000 ft. Industry authorities estimate that repairing failed cement jobs in deep, hot wells costs industry more than $100 million each year. Many failures occur because the Portland cement systems used today cannot stand up to the conditions in deep reservoirs. The team's work will begin with laboratory analysis of various Portland and non-Portland materials and mixtures to identify compositions that provide the optimum mechanical properties for extreme conditions, followed by upscale testing to determine performance in larger quantities. Finally, the supercement will be tested in three to six field applications in hot, deep wells. Total project cost is $2.5 million with DOE providing $1.5 million.

For further information, see DOE's Tech Line (www.fe.doe.gov/
techline/tl_deeptrek_2003sel.
shtml).

DOE's National Energy Technology Laboratory's (NETL) Microhole Technologies initiative is being developed based on successes from Los Alamos National Lab's Microdrilling feasibility study, a part of DOE's National Lab Partnership Program. Initial feasibility and proof 

of concept studies have indicated that wellbore diameters of 2-3/8 to 1-3/4 inches (microholes) using coiled tubing drill rigs are possible. Field tests have demonstrated that small diameter holes can be drilled to depths of 700 feet using a small-footprint coiled tubing unit. Positive results from these field demonstrations, along with modelling and laboratory tests, indicate that drilling microholes to depths of 5,000 feet can be achieved with relatively modest modification of existing drilling equipment and coiled tubing technology. Two primary drivers for this technology focus are radically reduced cost of subsurface access, both for shallow reservoir development and for expanded use of borehole seismic for reduced exploration risk, and reduced cost for reservoir monitoring.

To assist in the planning process, Spears & Associates, Inc. recently prepared an initial market evaluation (www.npto.doe.gov/
news/micholSpearsMarEval
Rep.PDF) documenting the state of the coiled tubing market and trends in drilling costs in the U.S. Producers, service companies and equipment suppliers met in Albuquerque in late April to provide additional industry input as a roadmap for technology development is prepared. Topics discussed at the meeting included: potential uses and benefits, needed capabilities, enabling technologies, technological barriers, target drilling and completion costs, and barriers to market penetration.

Workshop participants identified four microhole technology application areas that have potential considering capabilities of current or near term technology and industry interest: 1) Shallow development wells; 2) Reservoir data monitoring holes; 3) Shallow re-entry wells (deepening and multi-laterals); and, 4) Deep exploration hole re-entry for deeper target investigation. The development of technologies for improved capability/reliability for drillout of 4-1/2" casing would be included in most of these Microhole Program focus areas.

Microdrilling technology along with micro-instrumentation could provide potentially low-cost wells for exploration, long-term reservoir monitoring, and production. Costs and drilling fluid/cuttings volumes could be expected to be as much as one-fifth current practices, providing significant economic and environmental incentives. 

For further information, contact Roy Long, NETL, product manager, petroleum exploration and production, phone 918-699-2017, email Roy.Long@npto.doe.gov).