Research and Application of Heterogeneity Evaluation Technology for Low Permeability Reservoirs in the East China Sea

In recent years, more than ten times of well fracturing treatment have been implemented in the Oil and Gas Fields of East China Sea. However, the overall effect is not well with only a few wells obtaining commercial productivity after fracturing. Analysis shows that it is related to unclear understanding of reservoir heterogeneity. Aiming at the difficulties of deep reservoir burial, rapid lateral change of sand bodies, and strong heterogeneity in the study area, a suitable method for the evaluation of geological heterogeneity in this area is proposed. Firstly, based on the analysis of AVO lithology sensitivity attributes, innovative frequency-division filtering technology is used to predict the distribution area of favorable sand bodies and characterize the horizontal distribution of sand bodies. Secondly, evaluation of permeability of low permeability reservoir is based on micro pore structure analysis, combining imaging logging data to evaluate vertical heterogeneity. Consequently, well interval design with good homogeneity can be optimized. This method can improve the spatial resolution of reservoir and predict the sand body distribution characteristics more accurately, which can effectively evaluate reservoir heterogeneity. The research shows that the technology has a good application effect in a well, and the horizontal section achieves 100% sandstone drilling rate, which provides an important basis for well trajectory optimization and fracturing scheme design.