Methods And Technologies Study On Converted-wave 3D3C Seismic Exploration

Considerable progress of methods and technologies of converted-wave 3D3C seismic exploration have been made since the twenty-first century after a very long period of intensive research and development, and it is now extensively applied in offshore oil and gas exploration. In recent years, along with continuously improving and developing of converted-wave 3D3C seismic data acquisition, data processing and interpretation techniques, the number of onshore land 3D3C exploration pilot and industrial projects has risen rapidly as well. Major oil and gas companies have invested a great amount of manpower and material resources in this area, and the number of academic papers on multi-component seismic is greatly increased in global and regional seminars, such as the SEG 2007 annual meeting in San Antonio and 2008 annual meeting in Las Vegas. As converted-wave 3D3C data often carries more information about fracture, lithology and fluid property than P-wave does, it is more desirable to use multi-component seismic including both the P-wave and C-wave to explore complicated or hidden oil and gas reservoirs.For the sake of pushing the progress of industrial application of converted-wave 3D3C seismic technology, systematic researches have been done and significant achievements have been made in many aspects as follow.Converted-wave 3D3C seismic data acquisition:A series of advanced and practicable 3D3C acquisition parameter design and geometry analysis method are established according to the propagation characters of converted-waves, the request of receiving P and C waves in same geometry, and the good attributes distribution of CMP and CCP bins, combining characteristic of target layer and project task. Geometry of 3D3C acquisition was proposed, which coincide with the current economic and technological conditions, and satisfies completely the particular requests of converted-wave processing, reservoir prediction, cracks detection and gas-bearing recognition, etc.Converted-wave 3D3C seismic data processing:Many data processing technical problems have been solved such as 3D3C seismic data reorientation, coordinate rotation, denoise, converted-wave statics correction, surface consistent processing, converted-wave velocity analysis, residual statics, pre-stack time migration, etc. then P-wave and C-wave isotropic and anisotropic data processing flow chart have been established, which can satisfy the needs of fracture detection, reservoir prediction and gas bearing recognition by joint using P-wave and C-wave simultaneously.Converted-wave 3D3C seismic data interpretation:A lot of multi-component interpretation problems have been solved including converted-wave forward modeling, P wave and C wave joint calibration, time registration, frequency matching and phase correction, P-wave and C-wave horizon picking, etc. the concept of full-wave attribute has been proposed and the work flow chart of multi-component data interpretation by joint using P-wave and C-wave has been established.Multi-component reservoir prediction: Lithology discrimination and high quality reservoir prediction techniques have been established including many key technologies like P-wave and C-wave auto-matching pre-stack joint inversion, P-wave and C-wave post-stack simultaneously joint inversion, elastic impedance inversion, etc.Multi-component fracture detection: Including converted-wave 3D3C seismic forward modeling of multi-layer anisotropy media, AVAZ, VVAZ crack detection techniques based on P-wave azimuthal anisotropy, and new fracture detection techniques such as AVAZ based on C-wave azimuthal anisotropy, relative delta T and layer stripping based on shear wave splitting. Multi-component gas-bearing recognition: including gas-bearing recognition using wavelet decomposition, multi-scale frequency and absorption, and full-wave attributes analysis.Multi-component integrated application methods: Methods and technologies of comprehensive prediction and evaluation of deep ultra-tight fractured reservoirs in Western Sichuan Basin have been established by using full-wave attributes, based on researches of reservoir geological character, petrophysics, logging response and seismic response.Researches and applications of the above new seismic methods and technologies have conduced to essential contribution to the growth of gas reserves and production Western Sichuan Basin. The proposed wells such as X2, X3, X5, X8, X10, X11, X202, X301, etc. already got commercial production. As a result, the successful rate of exploration and production wells rises from the early 50% to 89%, and the high-yield well rate from the previously around 17% to over 67%.