Abnormal High Pressure and Tight Oil Enrichment of Lucaogou Formation in Jimusar Sag

摘要/Abstract

摘要： The tight oil reservoir of the Middle Permian Lucaogou formation in the Jimusar sag is of good hydrocarbon potential. Its enrichment mechanism is greatly different from that of conventional oil-gas reservoirs. This paper calculates the fluid pressure of this formation, establishes the abnormal high pressure distribution system of it, and combined with the geologic conditions, geochemical analysis and formation testing of key wells, it discusses the relationship between the abnormal high pressure and tight oil enrichment. The results show that the Lucaogou reservoir is of typical integrated source-reservoir structure, and the tight oil generated from high-quality source rocks in low mature-mature stages is characterized by self-generation and self-storage, or migrated in short distance between source rocks, which is the main reason for forming the abnormal high pressure. Such abnormal high pressure is widespread in the source rocks and the reservoirs, with lateral stability and connectivity, showing a certain “strata bound” characteristic;; with vertical differences in organic matter abundance and hydrocarbon generation ability in different strata, resulting in uneven distribution of the abnormal high pressure, indicating that there exists distinct interlayer remaining fluid pressure. Such a remaining fluid pressure could be the main force for vertical migration of the tight oil, and the distribution belts of big difference of the interlayer remaining fluid pressure might be the favorable area for tight oil enrichment.

关键词: Junggar basin, Jimusar sag, Lucaogou formation, tight oil reservoir, abnormal high pressure, enrichment

Abstract: The tight oil reservoir of the Middle Permian Lucaogou formation in the Jimusar sag is of good hydrocarbon potential. Its enrichment mechanism is greatly different from that of conventional oil-gas reservoirs. This paper calculates the fluid pressure of this formation, establishes the abnormal high pressure distribution system of it, and combined with the geologic conditions, geochemical analysis and formation testing of key wells, it discusses the relationship between the abnormal high pressure and tight oil enrichment. The results show that the Lucaogou reservoir is of typical integrated source-reservoir structure, and the tight oil generated from high-quality source rocks in low mature-mature stages is characterized by self-generation and self-storage, or migrated in short distance between source rocks, which is the main reason for forming the abnormal high pressure. Such abnormal high pressure is widespread in the source rocks and the reservoirs, with lateral stability and connectivity, showing a certain “strata bound” characteristic;; with vertical differences in organic matter abundance and hydrocarbon generation ability in different strata, resulting in uneven distribution of the abnormal high pressure, indicating that there exists distinct interlayer remaining fluid pressure. Such a remaining fluid pressure could be the main force for vertical migration of the tight oil, and the distribution belts of big difference of the interlayer remaining fluid pressure might be the favorable area for tight oil enrichment.

Key words: Junggar basin, Jimusar sag, Lucaogou formation, tight oil reservoir, abnormal high pressure, enrichment

LIAN Huan, ZHA Ming, GAO Changhai, TANG Yong, DING Xiujian, QU Jiangxiu. Abnormal High Pressure and Tight Oil Enrichment of Lucaogou Formation in Jimusar Sag[J]. 新疆石油地质, 2016, 37(zk(English) ): 14-19.

LIAN Huan, ZHA Ming, GAO Changhai, TANG Yong, DING Xiujian, QU Jiangxiu. Abnormal High Pressure and Tight Oil Enrichment of Lucaogou Formation in Jimusar Sag[J]. Xinjiang Petroleum Geology, 2016, 37(zk(English) ): 14-19.

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