New seismic attribute technology for predicting dissolved pore-fracture of deeply buried platform margin reef-beach system in Northeast Sichuan Basin, China

Abstract

The large reef complexes of the Upper Permian Changxing Formation, with a significant breakthrough for petroleum exploration, are an important target for petroleum exploration in the Yuanba area of the Sichuan Basin in SW China. The storage space types of reef complexes are dominated by the dissolved pore-fracture (DPF). However, using only single geophysical methods, it is difficult to predict effective distribution of DPF. Based on a combination of geological models and geophysics technology, this study proposes two new geophysical methods, including anisotropy coherence technique (ACT) and fracture intensity inversion (FII), to research the characteristics of DPF by faciescontrolling in Changxing Formation in Yuanba area. Two major findings are presented as follows: (1) the characteristics of DPF varying with facies are the result of different diagenetic and petrophysical property. The intensity of DPF decreases from reef and bioclastic bank to interbank sea and slope; (2) ACT can qualitatively identify the distribution of DPF with no-directional and dispersed distribution, while FII can quantitatively characterize the intensity of DPF development within various sedimentary facies. When integrated into the geological study, ACT and FII can provide an effective way to predict the distribution of DPF in similar geological settings and the predicted DPF have been supported by the historical well data. KEY WORDS: dissolved pore, fracture, reef-beach system, seismic attribute, Changxing Formation, Yuanba area, Northeast Sichuan Basin. INTRODUCTIONAs fracture-cavity systems in carbonate reservoirs undergo multiphase tectonic reconstruction, weathering and leaching, the prediction of dissolved pore-fracture (DPF), featured by non-directionality and heterogeneity, is a hot-button issue around the world. In the past few years, some geologists have carried out extensive research on the characterization and prediction of fractured carbonate reservoirs within the sequence framework, and also on how fractures have influenced the oil and gas accumulation, proposing a series of technical methods, such as logging data prediction, pre/post-stack inversion, coherent technology, curvature attributes and numerical simulation *Corresponding author: wangchao0502@163.com

Application of Multi-Attribute Crossplots to Tight Gas in X Area, Western China

“…Michelena (2011) [1] proposed facies probabilities from multidimensional crossplots of seismic attributes and helped to improve sand identification where sands were more anisotropic than the background in the application of tight gas. Chao Wang (2015) [2] proposed two new seismic attribute technologies including anisotropy coherence technique (ACT) and fracture intensity inversion (FII) to provide an effective way to predict the distribution of DPF in similar geological settings. However, the attribute ambiguity reduces the accuracy of the predicted results.…”