The Key Technology Research Of Seismic Processing In Lower Yangtze Carboniferous

The seismic and geologic features of the Lower Yangtze Area includes surfaces with complex water network, surfaces with developed quicksand, complex construct of Triassic and Upper Paleozoic, weaker seismic energy in Lower Paleozoic and so on, which lead to the low SNR of seismic data in carbonate strata, and restrict the deepen understanding of the geology in this area and the oil and gas exploration process. This paper is based on the data analysis of the existing geology, drilling, seismic and so on. Its main line is to improve seismic imaging quality of the complex geological structure in marine Paleozoic. Starting from raising the SNR, building and optimizing the velocity model and seismic prestack imaging and other aspects, the paper set the goal as to increasing weak reflected SNR in marine Paleozoic. The key aspects of the research are increasing seismic data quality of carbonate strata (reflected energy and SNR in marine Paleozoic), velocity model accuracy and image clarity and other. It formed the key technology series of pre-stack seismic imaging including the seismic acquisition and processing technology which improved the SNR, multivariate constraint depth domain modeling techniques and wave equation prestack reverse time migration technology, which were suitable for the seismic geological features of the marine carbonate formations of the Paleozoic in the Lower Yangtze region. The research breaks the main technical bottlenecks and effectively improve the seismic imaging precision of complex geological structure in the Paleozoic, rich the information of seismic reflection in Triassic and Upper Paleozoic, clear the stratigraphic contact and homed the fault accurately. This paper mainly analyze the low SNR seismic imaging difficulty of the marine carbonate rocks in Lower Yangtze in Huangqiao and Jurong region. In order to improve marine Paleozoic carbonate strata seismic imaging quality, the paper carryingon the research including complex wave field seismic imaging technology and the SNR improving. Starting from the SNR analysis, velocity modeling and seismic prestack imaging and other aspects, the paper focused on the technical studies of improving the reflected energy, SNR and image clarity in marine Paleozoic, formed the technology series including the seismic acquisition and processing technology which improving the SNR and multivariate constraint depth domain modeling techniques and seismic imaging technology which are suitable for seismic geological features of the marine carbonate formations in the Paleozoic. This method effectively improve the seismic reflection data quality and clarity of the complexity seismic imaging in Paleozoic carbonate strata in Huangqiao and Jurong region. In the seismic data profiles, the information of seismic reflection are enriched, the stratigraphic contact is clearing and the fault is homing accurately in Triassic and Upper Paleozoic. This method submitting 6 three level traps and 26,850,000 tons trap resources finally. The research results provide key technical support for the oil and gas reserves upgrade and building oil and gas test area in Huangqiao and Jurong region. The main technical innovations are as follows:1. Developing the denoising techniques of single-point high-density information reconstruction of seismic dataThe denoising techniques of information reconstruction are mainly based on the idea of maximizing the noise difference, reconstruction of the single-point high-density seismic information, to make the noise difference between each channel maximized, and then denoising. This processing technology not only can be achieved in time-space domain, but also can be achieved by frequency division. By this process, it can effectively improve the denoising effect and the accuracy of seismic imaging.2. Proposing the progressive denoising technology in very low SNR seismic dataDenoising the conventional noise component after further processing, we got the remaining valid signal, then we went back to the seismic data gradually. It ensured maximum signal energy efficiently, improved the SNR, and guaranteed the imaging results.3. Developing the processing technology of optimum energy prestack migrationThe seismic data in Lower Yangtze Carboniferous was lower SNR. Firstly, we improve the SNR by the processing methods mentioned above. Then we conducting the data with energy equalization to guarantee the seismic data volume remain true amplitude. Finally, we using the best of real energy to prestack migration image, ensuring the greatest degree of prestack imaging accuracy.4. Developing seismic wave field wave equation forward modeling analysis techniquesFirstly, we using the wave equation forward model to simulate field construction blasting. According to the noise level of real seismic data, we can add proper noise components in the forward model data. Then the single shot records, gather records, stacked section and various migration profile can be analysised. The results can not only guide the field construction of seismic data acquisition, but also guide the technology methods research on seismic data processing and interpretation5. Establising methods series and technical processes of seismic data processing and interpretation in complex carbonateBased on the series of lower SNR seismic data denoising techniques, seismic wave field wave equation forward modeling techniques, and optimum energy prestack migration technology. Establising methods series and technical processes of seismic data processing and interpretation in complex carbonate.