Abstract
Ultra-deep (7500–9000 m) Ordovician tight limestone heterogeneous fractured-vuggy reservoir is an important target of FuMan Oilfield in Tarim Basin. The strike-slip fault controlled reservoir is related to formation fracture and dissolution caused by geological stress. The seismic wave-field anomaly characteristics with different energy and irregular waveform are displayed in the seismic profile. Accurate identification of fractured-vuggy reservoirs wrapped in tight limestone is the direct scheme to improve production efficiency. Therefore, a new combination method flow of seismic wave-field anomaly recognition is proposed. In this process, the seismic data must be preprocessed initially, and on this basis, robust formation dip scanning is carried out. Secondly, the dip data is applied to the transverse smoothing filter to obtain the formation background data. Eventually, the seismic wave-field anomaly data is the residual between background data and original seismic data. This method has been applied in blocks with different structural characteristics and can effectively improve the resolution of strike-slip fault controlled reservoirs. Based on the results, the drilling success rate is increased to more than 95%, and the high-yield rate of oil tests is increased to 75% in 2021. Multiple applications indicate that the method is robust and can be popularized.
Highlights
The Tarim Basin in western China is rich in oil and gas resources [1], of which carbonate resources are about 7 × 109 t oil equivalent
After years of exploration and development, it has been recognized that abnormal seismic reflection is the main feature of Ordovician carbonate fractured-vuggy reservoir (FVR) [5]
Hydrocarbon migrates along the fault zone and accumulates differentially into the FVRs, which has the characteristics of differential accumulation [7]
Summary
The Tarim Basin in western China is rich in oil and gas resources [1], of which carbonate resources are about 7 × 109 t oil equivalent. The strong “beaded” reflection is well-matched with high-yield oil and gas wells (oil production rate of about 100 tons/day) [6,7] They are relatively easy to be identified in seismic profiles [12,13,14,15]. Interpreters are experimenting with root mean square amplitude attributes [28], structural tensor attributes [29,30], amplitude gradient attributes, and curvature attributes [31,32,33], etc It can still effectively differentiate strong “beaded” reflection features, and it is still not obvious to effectively identify strip-shaped messy reflection features. Through the application in multiple actual blocks of FMOF, remarkable results have been achieved
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