Joint reports


Calibrated Thermal Modeling and Fluid Inclusions Study: South Caspian Basin


  • The executive companies: GIA / Exxon
  • The year of publication: December 1996
  • Code: -
  • Volumes: total 1
    volumes with appendixes in same amount: 1



EXECUTIVE SUMMARY


Calibrated thermal models of the Azerbaijan sector of the South Caspian Sea were built in order to develop thermal boundary conditions for use in models in interested areas. Models are built on extensive geothermal data compiled by the Geology Institute of Azerbaijan National Academy of Siences (GIA). As part of this study we also evaluated the effect of sediment undecompaction on thermal histories.


Fluid inclusions in sandstones were examined to gain insight into the distribution and history of oil and gas in the basin. We constructed hydrocarbon yield models based on the thermal models to address the same question.


Our analyses indicate that the western South Caspian Basin is cold. Rapid recent sedimentation has driven the basin far from steady-state thermal conditions. In addition, little heat is fluxed into basin from the base of the sedimentary section, and the sediments generate low levels of radiogenic heat. Although undercompaction may reduce thermal conductivities by up to 20%, this effect is far overshadowed by non-steady-state thermal effects. These factors push the top of the oil window (based on maturities) to depths as great as 8000 m.


Interpreted low maturities throughout the Tertiary section preclude the generation of high-maturity gas (i.e. gas generated by cracking of oil) in that section. This interference combined with available data on gas geochemistry suggests that gas distribution is a source- related phenomenon. Fluid inclusions analyses offered no further constraints on this problem because hydrocarbon inclusions associated with the present basin system are absent.


Geothermal data provided by GIA include compilations of:
  1. Wellbore temperatures of shut-in exploration and production wells.
  2. Measurements of U, Th, and K concentrations of rock samples based omn spectral gamma ray data.
  3. Thermal conductivities.

We used these data in a 1-D compactoional burial and conductive heat flow model to calculate temperature histories; temperature data were used to calibrate the models. Published data on source rock character were used with the resulting temperature histories to calculate oil and gas yield histories for possible source intervals.


CONTENTS


Summary


Introduction

 
  • Geothermal Data: S.Caspian Basin. Evaluation of GIA Data and Physical Insights
  • Thermal Modeling of the S.Caspian Basin
  • Overpressure Modeling of the S.Caspian Basin:
     
  • Impact on Thermal Conductivities, Thermal States, and Maturation
  • Source Yield Modeling - Implications for the Distribution of Hydrocarbon Types

Conclusions


References

  • Appendix 1. Joint Study Agreement
  • Appendix 2. Temperature Data
  • Appendix 3. Radioactive Elements
  • Appendix 4. Thermal Conductivity data
  • Appendix 5. Stratigraphic Sections
  • Appendix 6. Summary Plots of Burial, Thermal, Overpressure, and Hydrocarbon Yield Models
  • Appendix 7. XRD Data of Shale Core Sample from Umid Structure
  • Appendix 8. Preliminary Results of Fluid Inclusions Analyses from the South caspian Basin, Azerbaijan