A Seismic Prediction Method for Thin Reservoir Sweet Spots in Low Permeability Gas Reservoirs

Abstract

The invention provides a thin reservoir sweet spot earthquake prediction method for a low-permeability gas reservoir. The method comprises the following steps: (1) calculating a pre-stack AVO gradientattribute; (2) calculating a post-stack frequency slope attribute; (3) calculating a weight coefficient; and (4) calculating a thin reservoir sweet spot attribute. The method disclosed by the invention not only solves the difficult problem that a conventional earthquake attribute analysis method is strong in prediction solution multiplicity but also better represents the specific earthquake response characteristics of the thin gas reservoir, has relatively high coincidence rate through real drilling verification, and realizes high-precision prediction of thin reservoir sweet spots.

Description

technical field [0001] The invention belongs to the field of oil and gas exploration and development, in particular to a seismic prediction method for thin reservoir sweet spots of low-permeability gas reservoirs. Background technique [0002] Tight and low-permeability natural gas resources account for about 40% of the total natural gas resources in my country. At this stage, this type of gas reservoir has a large reserve but a low degree of production. The prediction and characterization of relatively high-quality reservoir sweet spots in low-permeability gas reservoirs is an important task to increase the development benefits of such gas reservoirs. Among them, the concept of reservoir "sweet spot" was first proposed by the US Geological Survey in 2000, and it is defined as a tight sandstone gas block that can continuously provide 30-year production. Generally, most scholars believe that the "sweet spot" is the natural gas enrichment zone where the internal porosity and ...

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Problems solved by technology

However, the above methods are more ambiguous in predicting thin reservoir sweet spots, and cannot effectively identify thin reservoir sweet spots.

Tight low-permeability gas reservoirs are rich in resources, but most of the reservoirs are low-grade gas reservoirs with low permeability, low porosity, and low gas abundance. Subtle, the seismic response characteristics of sweet spots are fuzzy, and earthquake prediction is difficult. Conventional attribute methods or multi-parameter step-by-step evaluation methods cannot effectively characterize the development characteristics of reservoir "sweet spots". Therefore, how to correctly describe and predict the distribution of sweet spots in thin reservoirs is a key The key to the development and deployment of thin gas permeable reservoirs and the optimization and adjustment of well locations

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