A New Method On Prestack Elastic Parameters Inversion

Bright spot technique and AVO technique, rising in the eighties of the 20th century, have an important role in hydrocarbon detection. Many gas pools in the Gulf of Mexico and Sichuan and Shengli oil fields in China are discovered by using these techniques. In the past, the Bright spot technique and AVO technique were mainly used for hydrocarbon detection qualitatively, but they were rarely used to calculate lithology parameters quantitatively.AVO is a new technique in extraction of lithology parameters, and its fundament are Zoeppritz equation and its simplified formulae in spite of with errors used for real strata, especially for thin bed. Based on analysis of conventional elastic parameters inversion, the equation for horizontal multi-layered media built by Brekhovski, as a substitute for Zoeppritz equation, should be used for thin multi-layered media in order to make the inversion parameters more precise. But it is too complicated to be used in inversion directly. So in this paper it is simplified for a single thin bed firstly and then used in elastic parameters inversion.At first, the conventional elastic parameters inversion based on Shuey formula and simplified Shuey formula is discussed for the model of Chinese and Mexican, and the errors of inversion elastic parameters is analyzed. Furthermore, the problems of conventional AVO inversion are summarized.It is the errors between Zoeppritz equation and all kinds of its simplified formulae that caused the inverted parameters errors. The inversion errors are different for the cases bearing oil/gas of various areas in different depths, and no rules can be followed. So the simplified formulae of Zoeppritz equation don't apply to elastic parameters inversion precisely.In addition, many assumptions are provided when Zoeppritz equation and its simplified formulae are built. Zoeppritz equation only can be used to calculate the...