Identification of fractured reservoir and its effect on hydrocarbon accumulation of the Xujiahe Formation tight sandstone in the Northeast Sichuan Basin
The Nanjiang area in the northeastern Sichuan Basin is a low exploration area in the pre-mountainous belt of the Micang Mountains.And Well A1 drilled a natural gas reservoir without clear principle in the Xujiahe Formation.To distinguish the hydrocarbon accumulation model of gas fields in the fourth member of the Xujiahe Formation,the curvature of the stratum top surface and abnormal signals of well logs and seismic attribution have been carried out.Through these studies,the direction of the tectonic stress and fractured reservoirs which are controlled by curvature are identified.It is indicated that the distribution of the gas field is controlled by the distance of the Micang Mountain and the Daba Mountain.Where the Micang Mountain and the Daba Mountain stress together is the favorable zone.Fractures were developed with the relative curvature>0.2,and more frac-tures were open with the relative curvature>0.4.However,the gas would be dissipated if the fractured reser-voir was controlled by faults.After compaction,cementation and densification,the fractures can be used as geo-logical desserts to enrich natural gas in the fourth member of the Xujiahe Formation.With the orogenic move-ment of the Daba Mountains,the fractures were developed due to tectonic movements where the relative curva-ture was high.Hydrocarbon charged into the fracture traps of the fourth member of the Xujiahe Formation.
Tight sandstoneTectonic partitionFracture identificationSeismic attributionEffect on hydro-carbon accumulation
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