| Shale gas as an unconventional resource is the hot field of energy exploration.In this paper,the Shanxi Formation in the north of the Ordos basin is selected as the research object.According to the data of drilling,logging,seismic core description and laboratory analysis of cores,the geological features,geochemistry,reservoir properties,the sedimentary facies features,reservoir features and gas-bearing characteristics of the Shanxi Formation shale in the north of the Ordos basin were studied and two favorable exploration area is determined;Meanwhile,the amount of shale gas resources is estimated initially.Studies have shown that the organic matter of shale reservoir of the Shanxi Formation is abundance;The organic matter types mainly are ? type 2 and type ?;Organic matter maturity is high,Ro averaged 1.54%,belongs to the mature-post mature stage,which is helpful for organic matter pyrolysis gas.The Shanxi Formation shale has shale gas accumulation geological conditions.Shanxi Formation shales have a low porosity and a high permeability,and gas content of 1.06m~3/t,while the thickness of a single shale layer is relatively small,the main distribution from 10 m to 18 m.Brittle mineral content of the shales is 45.3% on average,and clay content is 50.7% on average.The shale gas resource abundance is low.However,the shales have a buried depth less than 3000 m and acquired production of 6.4 thousand cubic meters per day by fracturing,which implies a good shale gas potential.Considering all factors,eleven favorable areas are identified locating in the Yu106 area,and their shale gas resource can be 4560.39×108m~3;eleven favorable areas are identified locating in the Zhao100-Tao50 area,and their shale gas resource can be 6216.5×108m~3.Finally,selceting a favorable area in Zhao100-Tao50 area for productivity prediction,the first key factor of the well spacing is wellhead spacing,should be appropriate to the 600 m,the second key factor is the horizontal section length,should be more than 1200 m. |
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