DIAGENESIS AND RESERVOIR QUALITY EVOLUTION OF SHELF-MARGIN SANDSTONES IN PEARL RIVER MOUTH BASIN, SOUTH CHINA SEA

Document Type: Research Paper

Authors

Abstract

A study of the diagenetic evolution of sandstones from Panyu low-uplift in the Pearl River Mouth Basin was carried out to unravel the controls on shelf margin sandstone reservoir quality. The reservoir rocks, Oligocene volcanic clastic sandstones of the Zhuhai Formation, have a burial depth of 2765 to 3440 m. 70 samples were studied using the granulometric analyses, X-ray diffraction (XRD) analyses, porosity and permeability measurements, SEM observations, and mercury porosimetry measurements. The sandstones are fine- to medium-grained lithic sub-arkose, sub-litharenite, and sub-arkose with an average framework composition of Q72F13L15. High content and strongly altered volcanic rock fragments are the most important detrital components. In this work, typical diagenetic processes such as compaction, VRF (volcanic rock fragments) and feldspar dissolution, carbonate cements, quartz overgrowth, and clay cements are observed. Cements in eodiagenesis stage mainly include clay coating, early calcite and siderite. The main mesogenetic cements include kaolinite, ankerite, and minor quartz. The dissolution of VRF, feldspar, and carbonate cements is the most distinguishing feature which had controlled porosity and permeability. Carbon and oxygen isotopes were measured to discuss the carbon sources for precipitation and diagenetic temperatures of carbonate cements extensively developed in sampled intervals. Pore types in the analyzed samples change from a mix of primary to secondary pores. Primary pores have been destroyed by mechanical compaction or occluded by quartz, clay, and carbonate cements. Secondary pores were generated by the dissolution of VRF and feldspars during burial history. Its volume varied from trace to 8% and greatly improved the porosity of sandstones with increasing burial depth. Porosity varies from 4% to 20% in this work and is the highest for the samples where carbonate cement contents are low and dissolution is well developed.

Keywords


      [1]     Zhang Z. T., Shi H. S., and Qing C. G. “Study on Fault Sealability of Panyu Low Massif and North Slope of Baiyun Sag,” Fault-Block Oil Gas Field, 2010, 17, 1, 24-27 (in Chinese).

      [2]     Zhu J. Z., Shi H. S., and Pang X., “Natural Gas Origines and Gas Source Studies of Panyu Low-uplift in Pear River Mouth Basin,” Natural Gas Geoscience, 2005, 16, 4, 456-459 (in Chinese).

      [3]     Pittman E. D., Larese R. E., and Heald M. T., “Clay Coats: Occurrence and Relevance to Preservation of Porosity in Sand-stones,” in Houseknecht D. W. and Pittman E. D., eds., Origin, Diagenesis and Petrophysics of Clay Minerals in Sand-stones: SEPM Special Publication, 1992, 47, 241-264.

      [4]     Spötl C., Houseknecht D. W., and Longstaffe F. J., “Authigenic Chlorites in Sandstones as Indicators of High-tempera-ture Diagenesis, Arkoma Foreland Basin, U.S.A.,” Journal of Sedimentary Research, 1994, 64, 3, 553-566.

      [5]     Sun S. W., Shu L. S., Zeng Y. W., Cao J., etal., “Porosity-permeability and Textural Heterogeneity of Reservoir Sandstones from the Lower Cretaceous Putaohua Member of Yaojia Formation, Weixing Oilfield, Songliao Basin, Northeast China,” Marine and Petroleum Geology, 2007, 24, 109-127.

      [6]     Zhang J. L., Jia Y., and Du G. L., “Diagenesis and its Effect on Reservoir Quality of Silurian Sandstones, Tabei Area, Tarim Basin, China,” Petroleum Science, 2007, 4, 1-13 (in Chinese).

      [7]     Gier S., Worden R. H., Johns W. D., and Kurzweil H., “Diagenesis and Reservoir Quality of Miocene Sandstones in the Vienna Basin, Austria,” Marine and Petroleum Geology, 2008, 25, 681-695.

      [8]     Pang X., Chen C. M., Peng D. J., Zhou D., and Chen H. H., The Pearl River Deep-water Fan System and Petroleum in South China Sea, Beijing: Science Press, 2007, 6-7 (in Chinese).

      [9]     Ehrenberg S. N., “Preservation of Anomalously High Porosity in Deep Buried Sandstones by Grain-coating: Example from the Norwegian Continental Shelf,” AAPG Bulletin, 1993, 77, 1260-1286.

    [10]    Mansurbega H. S., Morad A., Salem R., Marfil M. A. K., et al., “Diagenesis and Reservoir Quality Evolution of Palaeocene Deep-water, Marine Sandstones, the Shetland-faroes Basin, British Continental Shelf,” Marine and Petroleum Geology, 2008, 25, 514-543.

    [11]    Berger A., Gier S., and Krois P., “Porosity-preserving Chlorite Cements in Shallow-marine Volcaniclastic Sandstones: Evi-dence from Cretaceous Sandstones of the Sawan Gas Field, Pakistan,” AAPG Bulletin, 2009, 93, 5, 595-615.

    [12]    Zhang C. M., Li S. T., Yang J. M., Yang S. M., et al., “Petroleum Migration and Mixing in the Pearl River Mouth Basin, South China Sea,” Marine and Petroleum Geology, 2004, 21, 215-224.

    [13]    Chen H. H., Chen C. M., Pang X., Wang J. H., et al., “Natural Gas Sources, Migration and Accumulation in the Shallow Water Area of the Panyu Lower Uplift: An Insight into the Deep Water Prospects of the Pearl River Mouth Basin, South China Sea,” Journal of Geochemical Exploration, 2006, 89, 47-52.

    [14]    Zhou D and Yao B. C., “Tectonics and Sedimentary Basins of the South China Sea: Challenges and Progresses,” Journal of Earth Science, Printed in China, 2009, 20, 1-12.

    [15]    Dong W., Lin C. S., and Qin C. G., “High Resolution Sequence Framework, Deposi-tional Pattern and Litho-stratigraphic Traps of Hanjiang Formation in Panyu Uplift, Pearl River Mouth Basin,” Geoscience, 2008. 22, 5, 794-801 (in Chinese).

    [16]    Guo X. W. and He S., “Aromatic Hydrocarbons as Indicators of Origin and Maturation for Light Oils from Panyu Lower Uplift in Pearl River Mouth Basin,” Journal of Earth Science, 2009, 20, 5, 824-835 (in Chinese).

    [17]    Yu X. H., Jiang H and Shi H. S., “Study on Depositional Characteristic and Diagenetic Evolvement in Panyu Gas Field of Peal River Mouth Basin,” Acta Sedimentologica Sinica, 2007, 25, 6, 876-884 (in Chinese).

    [18]    Zhu J. Z., Shi H. S and Pang X. Z., “Formation Source Rock Evaluation and Reservoired Hydrocarbon Source Analysis in the Deep-water Area of Baiyun Sag, Pearl River Mouth Basin,” China Offshore Oil and Gas, 2008, 20, 223-227 (in Chinese).

    [19]    Wu S. G., Han Q. H., Ma Y. B., and Dong D. D., “Petroleum System in Deepwater Basins of the Northern South China Sea,” Journal of Earth Science, Printed in China, 2009, 20, 124-135.

    [20]    Wang Q., Zhuo X. Z., Chen G. J., and Li X. Y., “Carbon and Oxygen Isotopic Composition of Carbonate Cements of Different Phases in Terrigenous Siliciclas-tic Reservoirs and Significance for their Origin: A Case Study from Sandstones of the Triassic Yanchang Formation, South-western Ordos Basin, China,” Chin. J. Geochem, 2008, 27, 249-256 (in Chinese).

    [21]    Craig H., “The Measurement of Oxygen Isotope Paleotemperatures. In Stable Isotopes in Oceanographic Studies and Paletemperatures,” Spoleto Conference in Nuclear Geology, Consiglio Nazionale delle Richerche, Laboratorio di Geologia Nucleare, Pisa, July 26-27 1965, 1-24.

    [22]    Dos Anjos S. M. C., De Ros L. F., Schiffer de Souza R., de Assis Silva C. M., et al., “Depositional and Diagenetic Controls on the Reservoir Quality of Lower Cretaceous Pendencia Sandstones, Potiguar Rift Basin, Brazil,” AAPG Bulletin, 2008, 84, 1719-1742.

    [23]    Mackenzie F. T., “Sediments, Diagenesis,
and Sedimentary Rocks,” Treatise on Geochemistry, Elsevier, 2006, 88, 412-415.

    [24]    Xu Y. C., Liu W. H., Shen. P., and Zhang X. B., “The Evolution Characteristics and Fractionation Mechanism of Carbon Isotopes in the Process of Multi-stage Hydro-carbon Generation,” Chinese Jour-nal of Geochemistry, 2006, 24, 1-8 (in Chinese).

    [25]    Zhen J. J., Hu H. F., Sun G. Q., and Ji L. M., “Carbon Isotopic Characteristics of Hydrocarbon Gases from Coal-measure Source Rocks- A Thermal Simulation Experiment,” 2006, 25, 167-172 (in Chinese).

    [26]    Zhang M. Q., Huang S. J., Wu Z. X., Wu S. J., et al., “Carbonate Cements and Their Formation Mechanism in Palaeogene Sandstones of Lishui Sag, East China Sea Basin,” Journal of Chengdu University of Technology (Science & Technology Edi-tion), 2007, 34, 3, 259-266 (in Chinese).

    [27]    Huang S. J., Xie L. W., Zhang M., Wu W. H., et al., “Formation Mechanism of Authigenic Chlorite and Relation to Preservation of Porosity in Nonmarine Triassic Reservoir Sandstones, Ordos Basin and Sichuan Basin, China,” Journal of Chengdu University of Technology (Science &Technology Edition), 2004, 31, 3, 273-281 (in Chinese).

    [28]    Houseknecht D. W., “Assenssing the Relative Importance of Compaction Proc-esses and Cementation to Reduction of Porosity in Sandstones,” American Association of Petroleum Geologists Bulletin, 1987, 71, 633-642.

    [29]    Dutton S. P., “Calcite Cement in Permian Deep-water Sandstones, Delaware Basin, West Texas: Origin, Distribution, and Effect on Reservoir Properties,” AAPG Bulletin, 2008, 92, 6, 765-787.