Efficient progressive exploration and exploitation technology for subtle reservoirs in the Oriente Basin and its applications to blocks 14 and 17 in Ecuador
In blocks 14 and 17 of Ecuador,both situated in the foredeep zone of the Oriente Basin,the main oil-bearing strata comprise the M1,U,and T members of the Napo Formation.The developed oilfields in these blocks have entered a high water-cut stage,posing challenges to resource replacement.The trend surface-driven,post-stack consistent processing of seismic data,the time-frequency attenuation-based calibration and interpretation of high-precision synthetic seismograms,and anisotropic-variable-velocity mapping,are jointly applied to finely characterize low-amplitude structures,with many low-amplitude structural reservoirs discovered.Thin layers'weak-reflection coefficients,determined through frequency-division iterative denoising,contribute to the reconstruction of effective post-stack broadband signals.With these signals as constraints,we quantitatively predict 2-to 5-m-thick tidal channel sandstones at a burial depth of 3 000 m through a seismic phase-controlled nonlinear inversion of waveforms,identifying several ultra-thin lithologic reservoirs in the M1 member.Based on regional hydrodynamic conditions,the oil-water contact trends of low-amplitude structural reservoirs,and the energy characteristics of reservoirs,we determine hydrodynamic oil reservoirs in the LU member and perform step-out drilling.The observation of numerous thin sections from cores reveals the presence of glauconites as cements and particles in the quartzose sandstone reservoirs.Accordingly,a dual-component volume model of glauconites for log interpretation is developed,allowing for reservoir evaluation and identification of low-resistivity reservoirs in the UT member.Based on the characteristics of tropical rainforest surfaces and subtle reservoirs in the subsurface,we achieve progressive exploration,evaluation,and rapid production onstream following the strategy of"overall deployment,batch-wise implementation,tracking and evaluation,and timely adjustment",with a success rate of over 90%for both exploration and appraisal wells.
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