Diagenesis and Burial History of the...Travis Peak Formation, East Texas. Digital Download

RI0164D. Diagenesis and Burial History of the Lower Cretaceous Travis Peak Formation, East Texas, by S. P. Dutton. 58 p., 43 figs., 11 tables, 1987. doi.org/10.23867/RI0164D.  Downloadable PDF.



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ABSTRACT
Sandstone in the Travis Peak (Hosston) Formation has been extensively modified by burial diagenesis. Permeability in much of the formation has been reduced to less than 0.1 md as a result of compaction, extensive precipitation of authigenic minerals, and minor pressure solution. Thin zones of higher porosity and permeability occur mainly near the top of the formation; porosity and permeability decrease with depth below the top. The Travis Peak Formation in East Texas is approximately 2,000 ft (600 m) thick; the top of the formation ranges from 5,800 ft (1,770 m) to 9,400 ft (2,870 m) below sea level.

Travis Peak sandstone is fine-grained to very fine grained quartzarenite and subarkose having an average composition of Q₉₅F₄R₁. Plagioclase feldspar is more abundant than orthoclase, and chert and low-rank metamorphic rock fragments are the most common lithic components.

The first authigenic cement to precipitate was illite, which coated detrital grains with tangentially oriented crystals. Dolomite cement also formed shortly after deposition at about 77°F (25°C) from a fluid with a δ¹⁸O composition of 0‰, probably seawater. Next, extensive quartz cement averaging 17 percent of the rock volume in well-sorted sandstone, occluded much of the primary porosity. Quartz cement is most abundant in the lower Travis Peak, in well-connected sandstone beds that were deposited in braided streams. Oxygen-isotopic composition of quartz overgrowths indicates that they precipitated from meteoric fluids at temperatures of 130° to 165°F (55° to 75°C). These temperatures occur at depths of 3,000 to 5,000 ft (900 to 1,500 m).

Dissolution of orthoclase and albitization of plagioclase followed quartz cementation and occurred before movement of the Sabine Uplift in the mid-Cretaceous. An abrupt loss of orthoclase occurs at 1,200 ft (365 m) below the top of the Travis Peak, and albitization is more extensive deeper in the formation. Illite (a second generation), chlorite, and ankerite precipitated after feldspar diagenesis; these late authigenic phases incorporate ferrous iron released by thermal reduction of iron compounds. Ankerite was derived primarily from early dolomite cement, but it incorporated some light carbon from maturation of organic matter and radiogenic strontium from feldspar dissolution. During ankerite precipitation, the oxygen-isotopic composition of pore fluids evolved from -4 to+2"/00 (SMOW); +24/00 is the average composition of Travis Peak water now.

Oil from Jurassic source rocks migrated into Travis Peak reservoirs in the Late Cretaceous. Later deasphalting of the oil filled much of the remaining porosity in some zones near the top of the formation with reservoir bitumen.

Keywords: East Texas, hydrocarbon resources, sandstone diagenesis, tight gas sandstone, Travis Peak Formation



CONTENTS

ABSTRACT

INTRODUCTION

DEPOSITIONAL HISTORY

METHODS

TRAVIS PEAK COMPOSITION

Framework grains

Feldspar

Plagioclase

Orthoclase

Rock fragments

Nonessential constituents

Provenance

Matrix

Cements

Authigenic quartz

Authigenic clay minerals

Authigenic carbonate cements

Major element composition

Isotopic composition

Feldspar

Other authigenic minerals

Solid hydrocarbons

Porosity

Pre-cement porosity

Permeability

Travis Peak fluids

ORGANIC GEOCHEMISTRY

Detrital organic matter

Source-rock quality

Thermal maturity

Reservoir bitumen

Elemental analysis

Chromatography

Travis Peak oil

Source of Travis Peak oil

BURIAL AND THERMAL HISTORY

Burial-history curves

Thermal history

Time-temperature index

INTERPRETATION OF DIAGENETIC HISTORY

lllite rims

Calcite cement

Dolomite cement

Quartz overgrowths

Cementation conditions

Paleohydrology

Variations in quartz cementation

Feldspar albitization and dissolution

Orthoclase dissolution

Albitization

Feldspar distribution

Development of secondary porosity

Authigenic clays

Ankerite

Hydrocarbon migration

Comparison with diagenesis in other Gulf Coast Mesozoic and Tertiary sandstones

CONCLUSIONS

ACKNOWLEDGMENTS

REFERENCES

 

Figures

1. Location of study area and wells from which Travis Peak cores were taken

2. Regional tectonic map of the central Gulf coastal province

3. Core control plotted against depth below the top of the Travis Peak

4. Stratigraphic nomenclature, East Texas Basin

5. Paleodip·oriented stratigraphic cross section A-A'

6. Core description of Prairie Mast No. 1A well

7. Core description of Clayton Williams Sam Hughes No. 1 well

8. Classification of 255 Travis Peak sandstone samples

9. Plagioclase volume as a function of depth below the top of the Travis Peak

10. SEM photograph of internal albite overgrowths

11. Plagioclase composition as a function of depth below the top of the Travis Peak

12. Orthoclase volume as a function of depth below the top of the Travis Peak

13. Paleogeologic map of the Early Cretaceous (Coahuilan)

14. Relation between total volume of cement and depth below the top of the Travis Peak

15. Frequency of observed sequences of major cements in Travis Peak sandstones

16. Photomicrograph of quartzarenite and SEM photograph of interlocking quartz overgrowths

17. Photomicrograph of primary and secondary pores and euhedral quartz overgrowths and SEM photograph of euhedral quartz overgrowths

18. Plot of δ18O of whole-rock quartz versus percent quartz overgrowths of total quartz

19. Plots of δ18O of whole-rock quartz versus percent quartz overgrowths of total quartz in samples from the upper part of the formationand samples from deeper in the formation

20. SEM photograph of authigenic illite fibers and albite

21. SEM photographs of thick illite cutans and clay cutan with authigenic illite

22. SEM photograph of authigenic chlorite

23. Photomicrograph of dolomite and ankerite cements

24. Chemical composition of carbonate cements

25. Plot of dolomite cement volume with depth below the top of the Travis Peak

26. Back-scattered electron image of dolomite and ankerite cements

27. Plot of ankerite cement volume with depth below the top of the Travis Peak

28. Plot of O¹³C versus δ¹⁸O composition of carbonate cements

29. Plot of reservoir bitumen volume with depth below the top of the Travis Peak

30. Photomicrograph of reservoir bitumen in primary porosity

31. Rippled sandstone with reservoir bitumen highlighting ripple faces

32. Plot of primary porosity with depth below the top of the Travis Peak

33. Plot of secondary porosity with depth below the top of the Travis Peak

34. Plot of porosimeter porosity with depth below the top of the Travis Peak

35. Inverse relationship between quartz cement volume and unstressed permeability in matrix-free sandstone

36. Inverse relationship between total cement volume and unstressed permeability in matrix-free sandstone

37. Plot of permeability with depth in the Travis Peak

38. Organic matter types classified by hydrogen and oxygen indices

39. Gas chromatographs of C₁₅+ saturate fraction of hydrocarbons extracted by dichloromethane from reservoir bitumen, Chapel Hill field, Smith County

40. Gas chromatographs of Travis Peak oil, Chapel Hill field, Smith County

41. Burial-history curves for the tops of the Travis Peak, Cotton Valley, Bossier, and Smackover Formations in Ashland S.F.O.T. No. 1 and Sun D. O. Caudle No. 2 wells

42. Burial-history curve for the Ashland S.F.O.T. No. 1 well showing when major diagenetic events may have occurred

43. Locus of possible water temperatures and δ¹⁸O compositions for authigenic quartz, ankerite, and dolomite

 

Tables

1. Travis Peak cores used in this study

2. Isotopic analyses of quartz

3. Isotopic analyses of carbonate cements

4. Strontium isotopic analyses

5. Composition of Travis Peak water

6. Values of weight percent total organic carbon, relative amounts of the major kerogen types, and average vitrinite reflectance of Travis Peak shale samples

7. Results of total organic carbon analyses and pyrolysis

8. Elemental analysis data of reservoir bitumen extracted from Travis Peak sandstones

9. Geochemical analyses of extractable fraction of reservoir bitumen from Travis Peak sandstones

10. Geochemical analyses of Travis Peak crude oil

11. Calculated time-temperature indices and corresponding vitrinite reflectance values



Citation
Dutton, S. P., 1987, Diagenesis and Burial History of the Lower Cretaceous Travis Peak Formation, East Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No.  164, 58 p.