Zhang Yanqing

The gradient of the amplitude spectrum of seismic data and its application in reservoir prediction

Summary The gradient of the seismic amplitude spectrum is the rate of the seismic reflection amplitude versus frequency in the effective band, which highlights the variation of the seismic data amplitude with different frequency, and reveals the quality of reservoir. The gradient of the seismic data amplitude spectrum is applied for prediction of plane distribution characteristics of a high-quality reservoir in the study area, which laid the foundation for exploring the lithologic reservoir, structural-lithological compound reservoir and delineating an efficient development block.

Application of carbonate reef-shoal reservoir identification technology in the Sichuan basin

Summary The exploration for reef-shoal reservoirs in the regions of Puguang, Longgang and Jiulongshan in recent years has shown a promising exploration future in the KaijiangLiangping trough area. Using pre-stack migration seismic information combined with drilling and logging results, technologies such as horizon-flattening, volume-curvature, sequence stratigraphy, and prestack inversion have been successfully used in the identification of bioherm in the Changxing formation and oolitic reservoir of the Feixianguan formation in the Longgangxi region. An assorted preliminary workflow for reef-shoal body identification is developed and may contribute an important reference for research in the similar areas.

Pre-stack inversion combined with geostatistical simulation to predict thin reservoirs

In the study area, delta front sands and distributary channel sands characterized by rapid lateral variations dominate the reservoir rock. Both extrusive (lava flow) and intrusive igneous rock facies are distributed randomly in the target interval. The resolution of the seismic data is low, therefore it is very difficult to predict thin reservoir rocks with a thickness less than 15 m. Based on rock-physics modeling, the S-wave data of the wells are simulated through the Greenberg-Castagna model, and the predicted S-wave data (S-wave prediction) are obtained. The rock-physical template of the study area is established which responds to oil sands, oil-show sands, wet sands, and non-reservoir rocks. A new attribute has been found which can determine the variation of the sand reservoir and fluids contained in the reservoir, and therefore the former problem is solved in which the fluids could not be predicted successfully with only one elastic parameter. The method first combines the pre-stack inversion with geostatistical simulation, and then derives the advantages from them, thus improving the precision of thin reservoir prediction.

Application of Greenberg‐Castagna model in igneous rock region

In recent years, with the extensive application of prestack inversion technology, the rock-physics modeling technique has become very popular. For sand-shale stratigraphy we can select a suitable rock-physics model to simulate and predict shear waves based on the available information such as geological features, reservoir characteristics and situation of fluid development in the study area. In a region with extensive development of igneous rocks (non-igneous reservoir), there is no existing models for igneous rocks, and therefore rock-physics modeling has become difficult. In this paper, we propose a methodology to take into account of the complexity features of different rocks in the study area, and to select appropriate existing model (Greenberg-Castagna model) to estimate S-wave velocities. We also set up different rock-physics templates for sands, mudstone, igneous rock and fluid (oil, gas and water).