Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China

Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China

The characteristics and formation of the pre-salt dolomite reservoirs in the fifth member of Ordovician Majiagou Formation in the mid-east Ordos Basin are investigated through observation of cores and thin sections, and geochemical analysis. (1) The pre-salt dolomites can be divided into dolomicrite...

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Main Authors: Siyi FU, Chenggong ZHANG, Hongde CHEN, Anqing CHEN, Junxing ZHAO, Zhongtang SU, Shuai YANG, Guo WANG, Wentian MI
Format: Article
Language:English
Published: KeAi Communications Co., Ltd. 2019-12-01
Series:Petroleum Exploration and Development
Online Access:http://www.sciencedirect.com/science/article/pii/S1876380419602703
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spelling doaj-ee80360e27fe412dad8a8f4ba765a65e2021-04-02T14:04:22ZengKeAi Communications Co., Ltd.Petroleum Exploration and Development1876-38042019-12-0146611531164Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW ChinaSiyi FU0Chenggong ZHANG1Hongde CHEN2Anqing CHEN3Junxing ZHAO4Zhongtang SU5Shuai YANG6Guo WANG7Wentian MI8State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China; Corresponding authorState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaInstitute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, ChinaSchool of Mines, Inner Mongolia University of Technology, Hohhot 010051, ChinaThe characteristics and formation of the pre-salt dolomite reservoirs in the fifth member of Ordovician Majiagou Formation in the mid-east Ordos Basin are investigated through observation of cores and thin sections, and geochemical analysis. (1) The pre-salt dolomites can be divided into dolomicrite, grain dolomite and dolarenite, in which the main reservoir space consists of intercrystalline pores and various dissolved pores. (2) The diagenesis in the study area is complex and mainly includes dolomitization, dissolution, filling, and recrystallization. (3) Multi-stages of dolomitization, including penecontemporaneous capillary concentration dolomitization, seepage-reflux dolomitization during penecontemporaneous and shallow burial stage, and burial dolomitization in later stage, are conducive to the preservation of primary pores and development of secondary pores. (4) Multi-stages of dissolution also have strong influence on the development of secondary pores; the secondary transgression and regression cycles during the contemporaneous-penecontemporaneous stage led to exposure and dissolution of soluble minerals and thus the generation of secondary pores. (5) In the burial stage, reservoir pores were further improved due to organic acid dissolution and the dissolution by hydrosulphuric acid from thermochemical sulfate reduction (TSR) and its product H2S. (6) High H2S concentration area in pre-salt reservoirs can thus be considered as targets for future exploration. Key words: Ordos Basin, Ordovician Majiagou Formation, dolomite, evaporites, dolomitization, dissolutionhttp://www.sciencedirect.com/science/article/pii/S1876380419602703
collection DOAJ
language English
format Article
sources DOAJ
author Siyi FU
Chenggong ZHANG
Hongde CHEN
Anqing CHEN
Junxing ZHAO
Zhongtang SU
Shuai YANG
Guo WANG
Wentian MI
spellingShingle Siyi FU
Chenggong ZHANG
Hongde CHEN
Anqing CHEN
Junxing ZHAO
Zhongtang SU
Shuai YANG
Guo WANG
Wentian MI
Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
Petroleum Exploration and Development
author_facet Siyi FU
Chenggong ZHANG
Hongde CHEN
Anqing CHEN
Junxing ZHAO
Zhongtang SU
Shuai YANG
Guo WANG
Wentian MI
author_sort Siyi FU
title Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
title_short Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
title_full Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
title_fullStr Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
title_full_unstemmed Characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the Ordovician Majiagou Formation, mid-east Ordos Basin, NW China
title_sort characteristics, formation and evolution of pre-salt dolomite reservoirs in the fifth member of the ordovician majiagou formation, mid-east ordos basin, nw china
publisher KeAi Communications Co., Ltd.
series Petroleum Exploration and Development
issn 1876-3804
publishDate 2019-12-01
description The characteristics and formation of the pre-salt dolomite reservoirs in the fifth member of Ordovician Majiagou Formation in the mid-east Ordos Basin are investigated through observation of cores and thin sections, and geochemical analysis. (1) The pre-salt dolomites can be divided into dolomicrite, grain dolomite and dolarenite, in which the main reservoir space consists of intercrystalline pores and various dissolved pores. (2) The diagenesis in the study area is complex and mainly includes dolomitization, dissolution, filling, and recrystallization. (3) Multi-stages of dolomitization, including penecontemporaneous capillary concentration dolomitization, seepage-reflux dolomitization during penecontemporaneous and shallow burial stage, and burial dolomitization in later stage, are conducive to the preservation of primary pores and development of secondary pores. (4) Multi-stages of dissolution also have strong influence on the development of secondary pores; the secondary transgression and regression cycles during the contemporaneous-penecontemporaneous stage led to exposure and dissolution of soluble minerals and thus the generation of secondary pores. (5) In the burial stage, reservoir pores were further improved due to organic acid dissolution and the dissolution by hydrosulphuric acid from thermochemical sulfate reduction (TSR) and its product H2S. (6) High H2S concentration area in pre-salt reservoirs can thus be considered as targets for future exploration. Key words: Ordos Basin, Ordovician Majiagou Formation, dolomite, evaporites, dolomitization, dissolution
url http://www.sciencedirect.com/science/article/pii/S1876380419602703
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