TY  - BOOK
AU  - Yan,Yousheng
AU  - Xu,Zengkui
AU  - Yi,Mingli
AU  - Wei,Xin
ED  - World Gas Conference (24th. : 2009 oct 5-9 : Buenos Aires, Argentina)
TI  - DELINEATION OF TIGHT GAS SANDS BY 3D-3C VSP
N1  - Trabajo presentado en el 24 WGC. Disponible en CD en la biblioteca. Solicite este trabajo por email a biblio@iapg.org.ar
N2  - This paper presents a new attempt to apply 3D VSP technology to delineation of tight gas sands in Sulige gas field, Erdos basin, north-west of China. In this area, the target formations are in the Permian and of thin thickness, poor porosity and low permeability with delta sedimentary environments. In general, the P wave impedance of dry sands is higher than that of cap beds (shale). However, if the sand is saturated with gas, its P wave impedances will be decreased so that the contrasts of P wave impedances between the sand and shale become smaller. Obviously, the conventional P wave exploration faces challenges in the studies of the presence and properties of this type of reservoir. 2D surface seismic technology is a major mean for gas exploration in this area. The reason is that surface conditions in most of the area are of complexity which make the 3D seismic survey difficult. The local geophysicists and geologists have done a lot of works on seismic data interpretation, reservoir analysis, well location design and so on. Although some other methods such as AVO and pre-stack inversion methods have been applied and also beneficial to gas exploration in this area, the poor surface and subsurface conditions decreased the fidelity of compressional and shear wave attributes (AVO) derived from the Z component(vertical component) data and made these methods be of limited help in some area. In recent years, many applications of 3D VSP (3-Dimension 3-Component Vertical Seismic Profiling) technology were presented. However, only a few of them showed the results based on the integration of PP and PSv waves. Some of typical case studies are"3D VSP PP and PS imaging used for structural interpretation in the onshore[1]"(Frederico Aguiar Ferreira Gomes et al, 2005), "3D VSP PP and PS imaging for carbonate reservoirs[2]"(Yan et al, 2007) and etc. Most of us tried to get the information as much as possible from a 3D-3C VSP data set but had to give up ultimately because of a series of difficulties in the data processing. As a result, the multi-component attributes in 3D-3C VSP data have not been fully applied to reservoir analysis. To solve some of the problems in gas reservoir exploration in this area, a multi-component exploration project was proposed and sponsored by China National Petroleum Corporation. In this paper, we only discuss the application of 3D-3C VSP data to the tight gas sands. Our works include optimizing geometry design indata acquisition, principal methods in data processing and new multi-component attributes applied in data interpretation. By integrating the 3D-3C VSP data with geological, drilling and logging data, we complete a comprehensive evaluation on the tight gas sands and propose a new well location for drilling
ER  -