The Geophysical Key Technologies Of Lingshui 17-2 Gas Field Gas Reservoir Description In The Western Deepwater Area Of The South China Sea

In recent years, Western South China Sea area gas exploration made a great breakthrough in deep water area, first discovered China’s first self-exploration of deep water high-yield gas field- Lingshui 17-2 gas field, the field proven geological reserves of over one hundred billion cubic meters. But in the field of deep water gas reservoir described aspects, still facing complex pattern of sand deposition, characterization difficult sand stratum lateral velocity changes, low accuracy and reliability of reservoir structure and uncertainty and large gas-bearing prediction problem. In order to improve the accuracy of deep water gas reservoi r description accurately evaluate the size of deepwater reserves of gas reservoirs, this paper by means of Lingshui 17-2 gas reserves study of deep water gas reservoir description of the three key technologies were studied to solve the deepwater area descr iption gas reservoir sand bodies and water channels characterization problem, time depth conversion problems, and gas-bearing reservoir prediction.For more deep water sand deposition, more watercourse erosion, sedimentation patterns complex, difficult pro blem of sand body characterization, first deposit law as a guide to the area, combined with seismic coherence slices, sliced interpretation frequency fusion technology to carry out large-scale canyons and waterways under the characterization; on this basis, small-scale sand under the description of the laws guiding the use of macro microscopic interpretation, use of space constraints canyons and waterways form of interpreting the scope of each sand body, two-dimensional, three-dimensional visualization of the combined interpretation to carry out technical explanation fine sand body characterization, precise implementation of the spatial distribution of deep water sand and waterways;For deep water lateral velocity changes, time-depth conversion difficult problem, compared to the industry when a variety of commonly used depth conversion method, on the basis of the implementation of the law of deep-water formation rate based on the analysis of a variety of time-depth conversion method applied in deep water, it is preferable that the velocity modeling approach applicable to deep-water deep conversion method. On the basis, has made a further study on the velocity cube optimization and the details of velocity modeling. Concern on the velocity optimization, based o n the analysis of the quality of raw velocity, using median filtering algorithm to optimize the quality of velocity cube, preferably the optimal filtering window and filtering times; Speed modeling, carried out preferably modeling horizon, according to the construction characteristics of sedimentary area, preferably the optimal control model horizon. Finally, the use of high-precision modeling of velocity model obtained complete each sand body time-depth conversion, to restore the true underground sand body structure, the use of well-proven method of cross-validated method for predicting the reliability of this method time-depth conversion, using this method, formation depth prediction relative error control in less than 0.5%.In view of the less number of deep well drilling, well control caused reservoir prediction and hydrocarbon prediction difficult problem, from the analysis of the petro physical characteristics, carried out post-stack reservoir prediction and pre-stack inversion, combined on a plane sed imentary fancies recognized statistical laws of drilling, using reservoir inversion results predicted plane distribution characteristics of reservoir properties; On the basis of the implementation of the reservoir, carried out based on the amplitude of the semi-quantitative analysis to quantitative gas prediction, using spectral decomposition technology-based comprehensive predicted gas area of each sand body, With the cross validation of boundary structure containing gas at the same time, accurate implemen tation of the gas area of each sand body.After this study, to solve China’s first self-deep water gas field- Lingshui 17-2 Gas Field gas reservoir description, fine characterization of sand, the implementation of time-depth conversion method, reservoir and gas prediction and many other aspects of difficulties. First using layer of well control and optimization of high-precision velocity control modeling technology applied to time-depth conversion based on median filtering method; For the first time carried out quantitative amplitude, spectral decomposition, predicted gas combinationing of attribute analysis to accurately predict reservoir and gas reservoir distribution deepwater turbidite sand bodies. For the first time to carry out quantitative amplitude, spectral decomposition, attribute analysis combining forecasting gas detection in the deep water area, and accurately predict reservoir and gas distribution of turbidite sand body. The research results provides a reliable data base for the reserves evalu ation of China’s first self-evaluation gas field Lingshui 17-2 gas field in deep water area, as well as provide effective technical reference for the ongoing China Sea deepwater oil and gas exploration.