Oil & Gas Geology ›› 2020, Vol. 41 ›› Issue (1): 223-234.doi: 10.11743/ogg20200120

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Simulation experiment of carbonate reservoir modification by source rock-derived acidic fluids

Qian Ding1,2,3(), Zhiliang He1,3,4,*(), Jingbin Wang2,3,5, Dongya Zhu1,2,3   

  1. 1. State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
    2. Petroleum Exploration & Production Research Institute, SINOPEC, Beijing 100083, China
    3. Laboratory of Structural and Sedimentological Reservoir Geology, Petroleum Exploration & Production Research Institute, SINOPEC, Beijing 100083, China
    4. China Petroleum & Chemical Corporation, Beijing 100728, China
    5. China University of Geosciences(Beijing), Beijing 100083, China
  • Received:2019-07-30 Online:2020-02-01 Published:2020-01-19
  • Contact: Zhiliang He E-mail:dingqian.syky@sinopec.com;hezhiliang@sinopec.com
  • Supported by:
    国家自然科学基金项目(41702134);国家自然科学基金项目(U1663209);国家自然科学基金项目(91755211);中国科学院A类战略性先导科技专项(XDA14010201)

Abstract:

The deep and ultra-deep carbonate reservoirs are the major targets of exploration, but their prediction is quite complicated due to the poor understanding of their formation and maintenance mechanism. It is essential to perform hydrocarbon generation and dissolution simulation experiments to quantitatively and qualitatively clarify the evolution process of source rocks and carbonate reservoirs in deep layers. In this study, a series of experiments were conducted with the limestone samples from the Ordovician Yingshan Formation in the Tarim Basin, and the low maturity source rock samples from Luquan County, Yunnan Province, via self-designed hydrocarbon generation and dissolution simulation equipments. The controlling factors accounting for the alteration of carbonate reservoirs and dissolution modification process by the complex acidic fluids associated with hydrocarbon generation in medium-to-deep burial environments were investigated using petrographic and geochemical methods. In the meantime, the transformation mechanism of surrounding carbonate reservoirs during hydrocarbon generation process of source rocks was explored. The results show that: during the medium-deep burial stage, acidic fluids including organic acid and CO2 associated with thermal evolution of source rocks could dissolve carbonate reservoirs, expanding their reservoir space, and thus improving porosity. Dissolution would decrease with the increasing burial depth. Whether the migrating fluids could improve the physical properties of reservoir largely depends on such factors as calcium carbonate saturation, fluid velocity, water/rock ratio, and original pore structure. The study can provide a theoretical basis for prediction of high-quality carbonate reservoirs in deep and ultra-deep formations.

Key words: organic acidic fluid, burial dissolution, deep-to-ultra-deep formation, carbonate rock, Ordovician, Tarim Basin

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