1 / 24

Richard Odom O- GeoSolutions CAARI 2010

Can accelerator-based radiation sources replace chemical-based sources in oilfield development? This article discusses the benefits, challenges, and technical advancements in using accelerators for radiation-based measurements in geophysical exploration.

nordman
Download Presentation

Richard Odom O- GeoSolutions CAARI 2010

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Richard Odom O-GeoSolutions CAARI 2010 Can accelerator-based radiation sources replace the chemical-based sources commonly used in geophysical exploration?

  2. Theme: Radiation-based measurements are an important tool in oilfield development, but it would be desirable to use accelerators rather than Radio-isotope sources. • Security, terrorism and RDD’s • Stewardship and liability • Personnel Safety and Exposure

  3. Predominate Applications: Formation Density Neutron porosity Well Logging with Radio-isotopes Source: 2Ci Cesium Source: 20Ci AmBe From Ellis

  4. Logging background: N-D synergy Water-filled limestone Water-filled sandstone Water-filled Shale Gas-filled sandstone

  5. Logging background: Neutron-Density plus resistivity Log Analyst’s Triple-Combo

  6. Neutron Generator (enabled) Measurements • Thermal Neutron Lifetime (Sigma) • Inelastic gamma spectroscopy for Carbon and Oxygen • Prompt-neutron logging for U235 • Cased-hole pulsed-neutron density

  7. Accelerator Time line • 1960’s Lab development of neutron generators • 1970’s commercialization Pulsed-neutron • 1980’s commercialization of neutron-induced spectroscopy systems (Carbon/Oxygen) • 1980’s development and field trials of LINAC density tool by Schlumberger • 1990’s accelerator-based Neutron Porosity • 1990’s Cased-hole pulsed-neutron density • 1990’s development of LWD pulsed-neutron density

  8. So what will it take to replace the radio-isotope sources? • Equivalent measurements within environment and economic constraints • Existing Neutron-Density are simple systems! • Existing analysis paradigms have deep roots • Neutron porosity is easier than density • Impetus • Value added • Regulatory

  9. Marketing Study of LWD features #4 Desirable Feature A New Integrated LWD Platform Brings Next-Generation Formation Evaluation Services, Weller et al. SPWLA 2005

  10. Value added • Neutron generator replaces AmBe source for neutron porosity. • Neutron generator and gamma detectors for pulsed-neutron density • But, in the end, focused density image was needed. The Cesium source is still used for imaging and density.

  11. Example: Cased-hole PN density Gamma Rays are Compton scattered in transit to a long-spaced detector Gamma Rays are created from inelastic scattering proximal to the neutron generator

  12. Two formations with same density, but different Hydrogen content Detector Target Improvements in a through-casing pulsed-neutron density log, Odom et al. 2001, SPE 71742

  13. Inverse methods Deterministic model for two gamma detectors and a fast-neutron detector 2-Group diffusion theory model

  14. Inverse methods Empirical Methods Outputs: Density Porosity Neutron Porosity Inputs: Pulsed-neutron measurements

  15. Value-added: Deeper penetration allows density measurement in cased-wellbores • Typical correlation: ~3 p.u. • Cased-hole Uncertainty • Hole-size • Cement quality • eccentricity • Where’s the value? • Moving the rig • Lowered liability • Open-hole accuracy

  16. So what will it take to replace the radio-isotope sources? • Equivalent measurements within environment and economic constraints • Existing Neutron-Density are simple systems! • Existing analysis paradigms have deep roots • Neutron porosity is easier than density • Impetus • Value added • Regulatory

  17. Constraints: Power Consumption • Optimal: 15 watts • Useable: 30 watts • Borderline: 100 watts • No Bueno: >200 watts These systems operate on very long extension cords or batteries

  18. Constraints: Size • Optimal: 1.75-inch O.D., 15-foot length • Useable: 2.75-inch O.D., 20-foot length • Borderline: 4-inch O.D., 25-foot length • No Bueno: >5-inch O.D., >30-foot length Constrained by wellbore size and use in logging stack

  19. Constraints: Operating Temperature • Optimal: 175 C • Useable: 150 C • Borderline: 125 C • No Bueno: < 100 C Wells are Hot!

  20. Constraints: MTBF or servicing • Optimal: 2000 operating hours • Useable: 500 operating hours • Borderline: 200 operating hours • No Bueno: <100 operating hours Ask BP, Failure is not an option

  21. Constraints: Sample Time • Optimal: 4 seconds • Useable: 8 seconds • Borderline: 16 seconds • No Bueno: < 20 seconds Time is Money!

  22. Constraints: System Cost • Optimal: $150K • Useable: $200K • Borderline: $250K • No Bueno: >$300K Typical cost Neutron-Density with sources: $150K

  23. Conclusions: Can it be done? • Technical • There are systems and techniques that could supplant need for radio-isotope logging • Regulatory: it’s a Wild-Card • Finding Added Value? Research!! • More radiation per watt • Improved ion sources • Improved targets • High voltage efficiency • Rugged and Tough solutions • Next generation Algorithms and Models

  24. Thank You!

More Related