Sandia National Laboratories and Security DBS have collaboratively examined the hard-rock drilling performance of a conventional drag-bit design that was run in conjunction with field tests of Sandia's prototype Diagnostics-While- Drilling (DWD) system for acquiring real-time downhole and surface data. This effort constituted the first two phases of work under the terms of a multi-partner Cooperative Research and Development Agreement (CRADA) that has been established between Sandia and four bit manufacturers for the purpose of developing and demonstrating "best effort" drag bits that are capable of drilling difficult formations such as those commonly found at geothermal energy production sites. For both CRADA phases completed to date, the test bit (Security DBS, Model PD 5) drilled in the same well-characterized hard lithologic interval at the GTI Catoosa Test Facility near Tulsa, OK. In each case, extensive time-resolved downhole and surface data were acquired with the DWD system. During Phase 1, an experienced driller controlled the drilling parameters only on the basis of standard rig instrumentation readings. For Phase 2, one or more drilling engineers continuously observed the streaming DWD displays and actively guided the drilling process. Significantly different results were achieved in Phases 1 and 2 for penetration rate and bit life, which are reported along with bit damage assessments and representative data from the unique downhole measurement sub that monitored conditions at the bit. This information has supported the development of designs and DWD-based drilling strategies for the "best effort" bits being tested during CRADA Phase 3.
This report describes development of a system that provides high-speed, real-time downhole data while drilling. Background of the project, its benefits, major technical challenges, test planning, and test results are covered by relatively brief descriptions in the body of the report, with some topics presented in more detail in the attached appendices.
The Geothermal Research Department at Sandia National Laboratories, in collaboration with Drill Cool Systems, Inc., has worked to develop and test insulated drillpipe (IDP). IDP will allow much cooler drilling fluid to reach the bottom of the hole, making possible the use of downhole motors, electronics, and steering tools that are now unusable in high-temperature formations. Other advantages of cooler fluid include reduced degradation of drilling fluid, longer bit life, and reduced corrosion rates. The paper describes the theoretical background, laboratory testing, and field testing of IDP. Structural and thermal laboratory testing procedures and results are described. Results are given for a field test in a geothermal well, in which circulating temperatures in IDP are compared with those in conventional drillpipe (CDP) at different flow rates. A brief description of the software used to model wellbore temperature and to calculate sensitivity to IDP design differences is included, along with a comparison of calculated and measured wellbore temperatures in the field test. Analysis of mixed (IDP and CDP) drill strings and discussion of where IDP should be placed in a mixed string are presented.