In the Shunbei area of the Tarim Basin in Xinjiang,carbonate fault-controlled fracture-cavity reservoirs with a burial depth of more than 7,000 meters have been developed.The internal heterogeneity of the reservoirs is so strong that the imaging accuracy of seismic data cannot distinguish and identify the internal reservoir structures of the reservoirs.Deployment of wells under the condition that there are no wells or the connectivity of reservoirs outside the wells cannot be described,leading to an excessive number of wells drilled in the same connected unit,or a low probability of drilling directly hitting the main large-scale reservoir.As a result,the increase in large-scale acid pressure operations lead to the increase in exploration and development costs,which restricts the efficient exploration and development of ultra-deep carbonate fracture-controlled reservoirs.Given the shortcomings in the application scope of the existing methods of identification and describing the reservoir connectivity of carbonate fracture-controlled reservoir collectives,a seismic description method for reservoir connectivity of carbonate fracture-controlled reservoir collective is proposed to apply to the region without wells in ultra-deep areas.Firstly,the spatial contour of the fault-controlled reservoir is obtained through three-dimensional engraving by using the seismic maximum likelihood attribute and the threshold value and combining with the attribute well earthquake calibration or the recognition of geological laws.Secondly,the formation pressure of any two points at the same elevation depth is obtained by the root mean square seismic velocity in the spatial range of fault-controlled reservoirs,and the pressure difference between the two points is compared to determine whether the reservoir between these two points has connectivity or not.This method of describing reservoir connectivity based on the principle of equal formation pressure at the same depth within the same connected fracture-cavity unit is effectively applicable after production verification,and can provide practical technical processes and method for determining the internal connectivity of reservoirs with similar geological targets in other areas.
fault-controlled fractured-cave storagereservoir connectivitycarbonate rockShunbei oil and gas fieldTarim Basin
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