Eogenetic karst and its control on reservoirs in the Ordovician Majiagou Formation, eastern Sulige gas field, Ordos Basin, NW China

Autor: Kang XIE, Xiucheng TAN, Min FENG, Baobao WANG, Shoukang ZHONG, Mengying YANG, Wancai NIE, Zhanfeng QIAO, Wei ZENG
Jazyk: English<br />Chinese
Rok vydání: 2020
Předmět:
Zdroj: Petroleum Exploration and Development, Vol 47, Iss 6, Pp 1246-1261 (2020)
Druh dokumentu: article
ISSN: 1876-3804
DOI: 10.1016/S1876-3804(20)60133-7
Popis: To further ascertain the origin of the Ordovician Majiagou Formation reservoirs in the Ordos Basin, the M54-M51 sub-members of the Ordovician Majiagou Formation in the eastern Sulige gasfield of Ordos Basin were taken as examples to analyze the vertical development characteristics of eogenetic karst and to discover the dissolution mechanism and its control on reservoirs through observation of a large number of cores and thin sections. According to detailed analysis of petrologic characteristics, the reservoir rock types include micritic dolomite, grain dolomite and microbialite which have mainly moldic pore, intergranular (dissolved) pore, and (dissolved) residual framework pore as main reservoir space respectively. The study area developed upward-shallowing sequences, with an exposure surface at the top of a single upward-shallowing sequence. The karst systems under the exposure surface had typical exposure characteristics of early dissolution and filling, indicating these reservoirs were related to the facies-controlled eogenetic karstification. With the increase of karstification intensity, the reservoirs became worse in physical properties.
Databáze: Directory of Open Access Journals