New fields,new types and resource potentials of natural gas exploration in Ordos Basin
Ordos Basin is rich in various types of natural gas resources.With the deep exploration from conventional to unconventional hydrocarbons and from shallow to deep strata,a set of natural gas reservoirs of new fields and new types are discovered in Ordos Ba-sin.Based on exploration achievements in recent years,the paper summarizes the new types of gas reservoirs,including deep coalbed methane,Taiyuan Formation limestone gas and bauxite gas,Ordovician presalt gas,marine shale gas,and deep Proterozoic gas,and further performs an in-depth analysis from the perspectives of sedimentary-tectonic background,source-reservoir configuration,and sealing-preservation condition.By analyzing the deployment relationship of source-reservoir-cap assemblage and summarizing the differences of accumulation characteristics and various natural gas,it is believed that these gas reservoirs generally have the accumu-lation model of near-source,self-generation and self-reservoiring.Based on determining the enrichment characteristics of gas reser-voirs,the paper evaluates the favorable exploration areas for natural gas reservoirs in various fields and clarifies their resource poten-tials and reserve scales.The favorable gas-bearing area of deep coal bed methane is 6.9 × 104km2;the resources are estimated to be 13.80 × 1012m3,expected to achieve a reserve of trillions of cubic meters.The favorable gas bearing area of Taiyuan Formation limestone gas reservoir is 1.5 × 104km2,with preliminary estimated resources of 1.6 × 1012m3,and a reserve scale of 5 000 × 108 m3.The exploration area of Taiyuan Formation bauxite is 7 000 km2,with natural gas resources exceeding 5 000 × 108 m3.The favorable exploration area for presalt natural gas in the Member 4 of Ordovician Majiagou Formation is 2.5 × 104km2,with an estimated reserve exceeding 7 000 × 108 m3.The favorable gas-bearing area of Wulalik Formation marine shale is 9 000 km2;the natural gas resources are estimated to be 1 × 1012m3,and two gas abundance zones have been identified.Two favorable areas of natural gas in the deep Proterozoic are optimized,with an exploration area of 5.71 × 104km2.The natural gas resources in Ordos Basin still have large exploration potential.
Ordos Basinnatural gas explorationnew fieldnew typeresource potential
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