Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (5): 957-971.doi: 10.11743/ogg20190502

• Petroleum Geology • Previous Articles     Next Articles

Effects of differential diagenesis of deep carbonate rocks on hydrocarbon zonation and accumulation: A case study of Yingshan Formation on northern slope of Tazhong uplift,Tarim Basin

Lyu Xiuxiang1,2, Chen Peipei1,2, Chen Kun1,2, Zhang Jie3, Qian Wenwen1,2   

  1. 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing), Beijing 102249, China;
    2. College of Geosciences, China University of Petroleum(Beijing), Beijing 102249, China;
    3. Research Institute of Tarim Oilfield Company Ltd., PetroChina, Korla, Xinjiang 841000, Chin
  • Received:2018-08-14 Revised:2019-05-27 Online:2019-10-28 Published:2019-08-17

Abstract: The carbonate rock reservoir on the northern slope of Yingshan Formation,Tazhong uplift,has undergone multistage diagenetic modifications of various kinds,featuring large thickness and deep burial depth.Based on the observation of core and thin section,the interpretation of well-logging data and the fracture identification by seismic attribute inversion,combined with the statistical analysis of logging and formation testing data,we found that the karst reservoir of the Yingshan Formation has gone through multistage dissolution and tectonic fracturing,and the reservoir space has experienced intensive,constructive rework,while the destructive cementation-filling is relatively weak.In comparison,the adjacent tight interval is mainly caused by intensive cementation and filling,and because the interval is remarkably weak in dissolution,its electric resistivity is significantly higher than that of adjacent reservoir intervals.So it is called "high-resistivity interval",a diagnostic character to identify tight layers.There are significant differences in diagenesis between the carbonate reservoirs and its adjacent tight caprocks.It is the differential diagenesis that results in the formation of multiple reservoir-caprock assemblages inside thick-bedded carbonate units.Vertically,multiple fracture-cavity sections (reservoir) alternate with tight sections (caprocks),having formed multiple superimposing reservoir-caprock assemblages.This has led to multiple hydrocarbon-bearing zones in the thick-bedded carbonate unit.Horizontally,due to the heterogeneity of carbonate rocks and the segmentation of strike-slip faults,the distribution of both karst reservoirs and tight high-resistivity caprock is restricted,leading to the hydrocarbon accumulation pattern in the Yingshan Formation characterized by vertical zonation and lateral compartmentalization.

Key words: differential diagenesis, tight layer (high-resistivity interval), carbonate rock, Yingshan Formation, northern slope of Tazhong uplift, Tarim Basin

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