Fluid replacement method based on pre-stack seismic data in sandstone reservoirs

Abstract

The invention provides a fluid replacing method of pre-stack earthquake data based on sandstone oil reservoir. The method comprises the following steps: determining a stone physical model; computing probable elastic parameters of mudstone and sandstone in a geological model and a combination form of the mudstone and the sandstone; simulating the pre-stack earthquake data, and computing a pre-stack earthquake AVO (amplitude variation versus offset) attribute when the sandstone is saturated with different fluids; establishing a pre-stack earthquake AVO attribute relation equation when the sandstone is saturated with different fluids, and providing a plate for the analysis of variation range of the pre-stack earthquake AVO attribute when oil reservoir fluid varies; simulating the relation between actual oil reservoir porosity and mud content, and further restraining the pre-stack earthquake AVO attribute relation equation and the plate when the sandstone is saturated with different fluids; computing an actual oil reservoir interface pre-stack earthquake AVO attribute before the fluid of the sandstone oil reservoir is replaced, and then computing the actual oil reservoir interface pre-stack earthquake AVO attribute after the fluid of the sandstone oil reservoir is replaced so as to finish the fluid replacement of the pre-stack earthquake data based on sandstone oil reservoir to improve the AVO attribute analysis accuracy.

Description

technical field [0001] The invention relates to an oil and gas field seismic reservoir description and monitoring method, in particular to a fluid replacement method based on pre-stack seismic data of sandstone reservoirs. Background technique [0002] Fluid replacement is often used to calculate the change of rock elastic parameters before and after reservoir fluid change, so as to calculate the seismic response caused by fluid change, which is a key step in seismic reservoir description and monitoring research. The purpose of fluid substitution is to establish the relationship between the water-saturated reservoir and the seismic response of the hydrocarbon-bearing reservoir. In time-lapse seismic research, based on fluid replacement and pre-stack seismic simulation, analyze the difference in pre-stack seismic AVO (Amplitude Versus Offset, amplitude versus offset) attribute differences caused by fluid changes in different reservoirs, so as to conduct time-lapse seismic fea...

AI Technical Summary

Problems solved by technology

Fluid replacement requires data such as porosity, rock matrix, fluid properties, and shale content, so fluid replacement can only be performed in reservoirs with well logging data, which greatly limits the application of this technology, especially In the exploration of offshore oil and gas fields, due to the lack of logging data, it is impossible or difficult to conduct fluid replacement analysis and research, which is very unfavorable for reservoir description and prediction

[0003] At present, the main problems of fluid replacement research are: 1. Fluid replacement research must be based on well logging curves. Fluid replacement research cannot be carried out at positions without well logging curves, and the application range is limited by well logging curves; 2. Fluid replacement is limited to Well logging data can only provide the change characteristics of the pre-stack seismic AVO response before and after the reservoir fluid replacement at the logging position, but not the characteristics of the reservoir, including parameters such as reservoir thickness, porosity, and shale content. After the change, the pre-stack seismic response changes Features provide useful information

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