New discovery and favorable areas of natural gas exploration in the 4tn Member of Ordovician Majiagou Formation by Well Mitan 1 in the eastern Ordos Basin

被引：0

作者：

Fu J. ^{[1
]}

Yu Z. ^{[2
,3
]}

Li C. ^{[1
]}

Wang W. ^{[1
]}

Huang Z. ^{[1
]}

Wu X. ^{[2
,3
]}

Wang S. ^{[2
,3
]}

机构：

[1] PetroChina Changqing Oilfield Company, Xi'an

[2] PetroChina Hangzhou Research Institute of Geology, Hangzhou

[3] CNPC Key Laboratory of Carbonate Reservoirs, Hangzhou

来源：

Natural Gas Industry | 2021年 / 41卷 / 12期

关键词：

Eastern Ordos Basin; Exploration direction; Natural gas; Natural gas accumulation condition; New Discovery; Ordovician; The 4tn member of Majiagou Formation; Well Mitan1;

D O I：

10.3787/j.issn.1000-0976.2021.12.003

中图分类号：

学科分类号：

摘要：

Recently, a new discovery of natural gas exploration was achieved in Well Mitan 1 in the 4tn Member of Ordovician Majiagou Formation (hereinafter referred to as "Ma 4 Member") in the Ordos Basin, indicating that Ma 4 Member in the eastern Ordos Basin has a good exploration prospect of natural gas. However, the natural gas accumulation conditions of Ma 4 Member in this area are rarely researched, which restricts the next deployment of natural gas exploration in this area. Therefore, based on new drilling results of Well Mitan 1 in the Ma 4 Member, combined with the data of field outcrop, seismic, logging, core, micro thin section, reservoir physical property analysis and geochemical analysis, this paper systematically studies the natural gas accumulation conditions, establishes a natural gas accumulation model of Ma 4 Member, and predicts the favorable areas of natural gas exploration. And the following research results are obtained. First, the natural gas reservoir of Ma 4 Member in the eastern Ordos Basin is an oil-type gas reservoir of self generation and self preservation, whose source rocks are distributed in the marine formation of Ma 3-Ma 1 Member in the Taolimiao and Mizhi depressions. Second, reservoirs of intra-platform beach facies and intra-platform mound facies are developed in Ma 4 Member along the Hengshan uplift and the uplift belt of the Mizhi Depression. The lithology of the intra-platform beach facies reservoirs is doloarenite (dolorudite) and powder-fine crystalline dolomite and the reservoir space is mainly intergranular pores, intercrystalline (dissolution) pores and microfractures, with an average porosity of 4.95%. The lithology of the intra-platform mound facies reservoirs is mainly microbial dolomite, porphyritic power crystalline dolomite, porphyritic limy powder crystalline dolomite and porphyritic dolomitic limestone, and the reservoir space is acted by intercrystalline (dissolution) pores and microfractures, with an average porosity of 2.47%. Third, faults and microfractures are the migration channels of Ma 3-Ma 1 Member marine gas source to Ma 4 Member. Fourth, lithologic and structural-lithologic traps are developed in Ma 4 Member, and there are many sets of limestone and gypsum-salt caprocks in it and its overlying formation, which provide favorable sites and barrier conditions for the accumulation of natural gas. In conclusion, Ma 4 Member in the eastern Ordos Basin has good conditions for natural gas accumulation and is the key replacement field of natural gas exploration in the future. The intra-platform beach in the Yulin-Jingbian area and the intra-platform mound in the Shenmu-Mizhi area are the favorable areas of natural gas exploration. © 2021, Natural Gas Industry Journal Agency. All right reserved.

引用

页码：17 / 27

页数：10

共 24 条

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