AVO Technique And Its Application In Gas-bearing Detection Of Sandstone Reservoir At Sulige Gas Field

AVO technique is used to identify lithology and detect oil gas through feature changing of the seismic reflection wave amplitude with offset. There are two methods of forward modeling and inversion: Forward AVO modeling use model to forward AVO modeling phenomenon and hydrocarbon-bearing pool feature analyze AVO response on liquid such as oil, brine and gas, establish a matched AVO detection under difference geological conditions. Forward AVO is used to qualitatively describe the reservoir, directly identify lithology and hydrocarbon from real seismic record. AVO inversion method extract the concealed lithological parameter from seismic information on the basis of amplitude changed with angle of incidence, estimate seismic parameters of the rock. It's a very important method to predict lithology and hydrocarbon quantitatively.The effective reservoir is characterized by thin, rapid lateral variation in the eighth member of Shihezi Formation in Sulige gas field. It belongs to fluvial-delta sandstone lithologic gas reservoir with strong heterogeneity, low porosity and low permeability. Based on logging and petrophysics analysis, by forward modeling, the thesis study of AVO response on seismic information in the eighth member of Shihezi Formation in Sulige Gasfield, the elastic parameters of the effective reservoir were obtained by prestack inversion, the comprehensive explanation of elastic parameters can afford reference to constitute development plan reasonable.AVO technique include a variety of methods, they have own characteristic and adaptability. According to the deposit feature of reservoir and to be solved geology problem in study area, the thesis chooses the most suitable method. Main research contents and conclusions of the thesis are as follow:1. Because there is no S-wave well-log information in the work area, S-wave well log are estimated by Petro physics, which is used to synthesis seismic gathering of known well and forward AVO modeling analysis.2. Parameter combination were analyzed which is better sensitive to the effective reservoir, the use of hydrocarbons indication factors, mimetic S-wave reflection coefficient and Poisson's ratio change rate can predict effective reservoir distribution.3. Pre-stack elastic parameter inversion obtained various offset EI, VP/VS, Poisson's ratio, and through these parameter predict reservoir quantitative.