Study On The Thin Layer Reservoir Of Baxigai Formation In Yudong 7 Reservoir

The Cretaceous reservoir in Yudong 7 block is located at the southeast end of Kalayuergun tectonic belt and the southwest end of Yingmai No.7 fault tectonic belt.It is adjacent to the Kuche oil generation depression in the north,and is located in the "Golden Triangle" area of oil and gas enrichment.The generated oil and gas migrated along the two major unconformity at the bottom of the Paleogene and the bottom of the Cretaceous towards the south for a long distance.The oil and gas resources are relatively abundant,and seven types of structural,fault block,and lithologic oil reservoirs have been discovered in adjacent areas,including Yudong 1,Yudong 2,Yingmai 17,and Yingmai 21 Since the discovery of Yudong 7 reservoir in 2016,the reservoir has realized the efficient exploration and development of "one year of exploration and discovery,two years of evaluation and control,and three years of exploration and construction".All the productivity indicators are better than the scheme design,and it is a favorable block for rapid production construction,which can realize the benefit development to the maximum extent.The Yudong 7 Cretaceous Brazilian reorganized reservoir belongs to a structural-lithological composite reservoir,with a burial depth of 5000 meters,a single sand body thickness of only 2-5 meters,and significant lateral variation.With the continuous deepening of development,a series of urgent geological problems have emerged: unclear understanding of the plane distribution pattern of sand reservoirs,which affects the evaluation and deployment of rolling well locations;Multiple sets of sand bodies are vertically stacked,and the oil-water interfaces of each small layer are inconsistent,which affects the production capacity construction of development wells;The connectivity of small layers is poor,and the water injection effect of water injection wells is not good.Therefore,it is necessary to optimize the injection production well network.This study combines the seismic and geological difficulties of predicting thin sand layers in this area to form a targeted matching technology for thin sand layer prediction: by identifying the macroscopic distribution characteristics of sand bodies through seismic attributes and seismic slices;By comparing the small layers of single and connected wells,clarify the sedimentary microfacies characteristics and vertical stacking of sand bodies in the study area;Through fine well seismic calibration,on the basis of analysis and reconstruction of reservoir sensitivity curve,multiple rounds of geostatistics inversion and high-precision waveform indication inversion were carried out.This study comprehensively applied various key technologies for predicting thin reservoirs,laying the foundation for each other and verifying each other,resulting in high prediction accuracy.The precise characterization of the planar distribution pattern of sedimentary facies has been achieved,which can provide a basis for evaluating the deployment of rolling well locations;Vertically,the extension and superposition characteristics of several sets of sand bodies were effectively identified,and the thickness distribution prediction maps of four sets of small sand beds were obtained.The connectivity prediction results of small sand bodies were in good agreement with the production dynamic information,which could provide a reliable data basis for the adjustment and optimization of the development plan in the area.