Shale reservoir brittleness index calculation method and system

Abstract

The invention discloses a shale reservoir brittleness index calculation method and a system. The method comprises the steps of estimating a rock skeleton model is established, and calculating the elasticity modulus and density of the rock skeleton model; calculating a single-layer isotropic elastic rigidity tensor of the rock skeleton model according to the elasticity modulus and the density of the rock skeleton model; according to the single-layer isotropic elastic stiffness tensor, calculating a transverse isotropic elastic stiffness tensor of the rock skeleton model; adding cracks into therock skeleton model, obtaining a shale reservoir model, and calculating the elastic rigidity tensor of the shale reservoir model; calculating the Poisson's ratio and the Young's modulus of the shale reservoir model according to the elastic stiffness tensor and the logging density of the shale reservoir model; and calculating the brittleness index of the shale reservoir model according to the Poisson's ratio and the Young's modulus of the shale reservoir model. According to the method, the brittleness index of the shale reservoir is rapidly, simply and conveniently calculated through element logging and rock physics, and necessary parameters are provided for shale gas reservoir prediction, brittleness evaluation and crack prediction.

Description

technical field [0001] The invention relates to the field of oil and gas seismic exploration and development, and more specifically, to a method and system for calculating the brittleness index of shale reservoirs. Background technique [0002] With the development and utilization of oil and natural gas resources, the reserves of conventional porous oil and gas reservoirs are decreasing day by day, and the difficulty of development is gradually increasing. The direction of oil and gas exploration is gradually shifting from shallow to deep, and from conventional oil and gas reservoirs to special oil and gas reservoirs. As an important place for oil and gas storage—reservoir research will gradually develop from conventional porous reservoir research to other types of reservoir research, especially fractured reservoirs have attracted the attention of many petroleum geologists in recent years. broad interests. At the same time, with the rapid development of unconventional natur...

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Problems solved by technology

In this way, there are the following problems: First, the brittleness index calculated based on the mineral composition and the brittleness index calculated based on the elastic parameters have different parameters and calculation formulas, so the comparability is poor; the second elastic parameters often include minerals Composition and its content, pore fluid, fractures and other factors, while the calculation method based on mineral composition only includes mineral composition and content, without considering factors such as pore fluid and fractures, so the result may not be very accurate

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