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Raymond D.,Sandia National Laboratories | Knudsen S.,Sandia National Laboratories | Blankenship D.,Sandia National Laboratories | Bjornstad S.,USN Geothermal Program Office | And 2 more authors.
Transactions - Geothermal Resources Council | Year: 2012

Geothermal drilling is hampered by the challenges of hard rock, fractured formations, and high temperatures. This drilling difficulty has traditionally been a point of distinction between geothermal and oil and gas applications yet recently this difference is less pronounced as the oil and gas industry targets more challenging formations for sustained production. This synergy can benefit the geothermal industry as technology developed for oil and gas, backed by significant research and testing, can be adapted for use in geothermal drilling. The work described herein demonstrates the use of mature oil and gas drilling technologies on an actual geothermal well construction project. The principal objective is to develop and demonstrate Enhanced Geothermal Systems (EGS) drilling solutions based upon mature, proven rock penetration systems that have been used in the oil and gas industries to penetrate hard rock formations. Polycrystalline diamond compact (PDC) bits are routinely used in the oil and gas industry for drilling medium to hard rock but have not been adopted for geothermal drilling, largely due to past reliability issues and higher purchase costs. The Sandia Geothermal Research Department has recently completed a field demonstration of the applicability of advanced synthetic diamond drill bits for production geothermal drilling. Two commercially-available PDC bits were tested in a geothermal drilling program in the Chocolate Mountains in Southern California. These bits drilled the granitic formations with significantly better Rate of Penetration (ROP) and bit life than the roller cone bit they are compared with. Drilling records and bit performance data along with associated drilling cost savings are presented herein. The drilling trials have demonstrated PDC bit drilling technology has matured for applicability and improvements to geothermal drilling. This will be especially beneficial for development of Enhanced Geothermal Systems whereby resources can be accessed anywhere within the continental US by drilling to deep, hot resources in hard, basement rock formations.


Pendley M.,NOV Downhole
Materials Science and Technology Conference and Exhibition 2010, MS and T'10 | Year: 2010

Sulfide stress cracking (SSC) has been the subject of investigation since the late 1940's, when a mysterious form of brittle failure began to be observed in steel equipment used to produce oil and gas containing hydrogen sulfide. While the role of hydrogen sulfide in promoting increased levels of hydrogen in steels was recognized early on, researchers disagreed on the mechanism responsible for SSC. Initial theories that SSC was a form of stress corrosion cracking eventually gave way to the current understanding that the phenomenon is caused by hydrogen embrittlement. Research into the effects of hardness, microstructure, chemical composition, and other factors in determining the susceptibility of steels to SSC led to the establishment of industry standards for SSC-resistant materials. Copyright ©2010 MS&T'10®.


Barton S.,NOV Downhole | Weeden R.,NOV Downhole
Society of Petroleum Engineers - International Oil and Gas Conference and Exhibition in China 2010, IOGCEC | Year: 2010

The increased use of hole opening tools remote from the drill bit has led to a critical need to understand the interaction between the drill bit and the hole opening tool itself. Problems that can result from improper matching include vibration, inability to open hole, mechanical damage to string tools or to the bit, and sub-optimal drilling performance. This paper explores the theoretical relationship between bit and reamer and modeling the relative aggressivity and stability of both tools, building on already established indices for predicting and comparing the performance of bits. It reviews the calculations and methodology of placement and development of both the bit and reamer for optimal interaction and performance. It also considers stabilization of the hole opening tool using both concentric and eccentric devices. The paper also reveals the development of an interactive, intranet tool. This software incorporates logic regarding the configuration of the reamer and assesses these against key characteristics of the drill bit. The tool enables the user to accurately select the drill bit that best complements the reamer that will be utilized. A number of examples from global applications are presented. These demonstrate reduced vibration, improved hole quality and hole opening performance, superior penetration rates, and overall significantly reduced drilling costs. Copyright 2010, Society of Petroleum Engineers.


Baez F.,NOV Downhole | Barton S.,NOV Downhole
SPE/IADC Drilling Conference, Proceedings | Year: 2011

This paper focuses on technology development for improving drilling performance in natural shale gas plays. These wells involve long horizontal laterals with frequent problems in controlling tool face and maintaining ROP. This results from a number of factors including, high tortuosity through the build section, use of high bend settings on directional motor assemblies, sub-optimal hydraulics, and drill bits with compromised aggressivity. A combination of technologies can be used to dramatically increase performance in these challenging sections by limiting resistive torque, maximizing bit hydraulics, and improving weight transfer. In each example, a separate engineered solution is introduced. These include; • A novel tool that vibrates the drill string with low frequency, low amplitude axial vibrations to reduce drag and dramatically improve weight transfer to the bit. This tool has been used successfully in hundreds of horizontal wells • A specific sealed bearing, motor technology that delivers 100% of the mud flow to the bit. Advantages of full flow include increased bit hydraulics (improved ROP in Shale), and no detriment in response when using tools below the motor that rely on pressure or flow to activate. Run data demonstrates a 37% average increase in ROP compared to conventional sealed bearing motors that rely on flow restrictor bypass leakage for seal performance • Development of a unique flexible bit design, specifically for directional applications. These bits contain novel features that allow rapid design modifications to be performed locally, significantly reducing response time, and allowing the drilling program to proceed at a much faster pace than previously possible Case studies are documented where these solutions have proven extremely successful in gas shale plays. The savings produced by the improvement in drilling performance has greatly assisted the economic viability of continued development in these applications. Copyright 2011, SPE/IADC Drilling Conference and Exhibition.


Berkman S.,NOV Downhole | Stokes T.,NOV Downhole
World Oil | Year: 2011

The NOV Down-hole's 58th annual rig census reports that the total available rig counts for both the US and Canada receded in 2011 despite of an increase in activity for both markets. The statistics from the 2011 census include that the US rig fleet had a net decline of 72 units in 2011, causing the total available count to fall about 2%. There were 262 rig additions and 334 rig deletions during the year 2010. The census report that a number of the US rigs, 315 units, were retired from active service over the year 2010. ODS-Petrodata, which assists in compiling the offshore census data, reports that another 55 units are scheduled for worldwide delivery by the time the 2012 census, is taken next spring. The available count for global offshore mobile units is now 794 units, a net increase of 49 rigs, or 7%. The worldwide offshore fleet is widely distributed, with the US and the Middle East in the lead, followed closely by Southeast Asia and South America.

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