The Application Of Fracture Prediction Technique In WD Area Using Multi-method

WD area lies in the middle of Sichuan basin. In this area, Xujiahe strata was deeply buried, whose lithologic character is compaction. So the porosity of the conventional reservoir does not develop. According to the predecessor's study: The frequent tectonic movements especially the Himalayan tectonic movement cause fault developed in the region,but actually drilling data indicate that: fault in this region has been filled. The fracture around the fault is un-developed and its distribution is very complex and changeable. Through a comprehensive analysis with drilling and seismic data we know that: the reservoir in Upper Triassic Xujiahe sandstone layered is not packaged gas reservoir, but a sizes varying oil or gas field with un-regularly shape. Between each block there is compaction sandstone,mudstone and shale. The block is also spread by them. In the Sandstone layer, whether we can obtain of the industry flow of oil and gas just decided we encountered the fracture during drilling the well or not? The distribution of fracture directly restricts the development and explore of oil & gas. Accurately prediction the distribution of the fracture has significant means for finding drilling objectives and the development and explore of oil & gas field. The main reservoir in WD area is fracture reservoir, especially the fracture in sandstone has particularly contribution for the output of oil & gas. After many years'development and exploration in WD area, the rate of getting high-output is low in XuJiahe stratum. After WD7 well get rich oil and gas output, the follow-up drilled well WD8, WD11 did not get industrial oil & gas. The financial lose is great. The mainly reason is the compaction lithologic character of the sandstone, the heterogeneity of the reservoir, and non-sensitive characters of the seismic response. The conventional post-stack geophysical method which have strong multiple ambiguous for the fracture prediction is unable to meet the needs of modern oil & gas development and exploration.The research on fracture exploration started lately. The technology about fracture prediction is also not mature. Although some treatises and technology appears, there is a lot of disagreement between each other. So far, there have no integrity technology for fracture prediction. The main fracture prediction technology prevalent in industrial field is attribute analysis based on P-wave, the technology based on the S-wave, the technology based on the case of fracture and the technology based on the P-wave anisotropy. This paper is mainly to take Xujiahe stratum as an example to discuss how to use multi-methods to analysis of the distribution of the fracture in WD area. I take the causes of fracture and the P-wave response character as the principal line。First, analysis P-wave gather anisotropy response character to get the fracture density and azimuth, Then, use seismic face to analysis the sediment character and use tectonic stress field simulation technology to analysis and evaluation the fracture developing zones, which is help for explanation the causes of fracture.