Rapid calculation method for porosity of coal seam fracture

A fast calculation technology for cracks and pores, which is applied in the direction of earthwork drilling and production, wellbore/well components, etc., can solve problems such as large influence, inaccurate calculation methods, poor drilling environment, etc.

Active Publication Date: 2012-07-04
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

However, due to the complex anisotropy and heterogeneity of coalbed methane formations and the generally poor drilling environment, the existing calculation methods for the fracture porosity of coalbed methane reservoirs are extremely inaccurate
[0003] 1. The conventional use of neutron, density and sonic logging is greatly affected by the borehole environment. Therefore, the method of using the combination of neutron, density and sonic logging to determine fracture porosity cannot obtain the technical gua

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  • Rapid calculation method for porosity of coal seam fracture
  • Rapid calculation method for porosity of coal seam fracture
  • Rapid calculation method for porosity of coal seam fracture

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specific Embodiment approach

[0044] A method for quickly calculating coal seam fracture porosity, the method is as follows:

[0045] First, judge the occurrence of fracture development

[0046] According to the development degree of horizontal fissures and vertical fissures, the occurrence of fissures can be divided into three situations: ①The horizontal fissures are relatively developed, and the vertical fissures are not developed; ②The development degree of horizontal and vertical fissures is equal; Not developing;

[0047] Let the state parameter a be the ratio of horizontal fractures to the total fracture porosity, which is used to represent the development and occurrence of fractures; in practical applications, the development and occurrence of coal seam fractures can be judged according to the dual laterolog response characteristics of fractured formations, as shown in formula (1 ), where R d , R s Respectively represent the deep and shallow lateral apparent resistivities;

[0048] ...

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Abstract

The invention relates to a rapid calculation method for the porosity of a coal seam fracture. In the method, a fracture development occurrence identification part and a fracture porosity calculation part are utilized. In the fracture development occurrence identification part, according to the method, a deep lateral apparent resistivity difference is utilized and is particularly combined with the distribution condition of the resistivity of coal seam bed rocks, so as to be used for observing the development condition of a horizontal fracture, a vertical fracture and the combination thereof. In the fracture porosity calculation part, two groups of orthogonal or heterotropic fracture characteristics are mainly developed according to a coal seam; and the according to the method, three groups of computational formulas the number of which is 9 in total of the porosity of the fracture according to a fracture development occurrence identification result and a distribution range of the coal seam resistivity are determined. According to the method provided by the invention, by aiming at the characteristic of large resistivity difference or variation range of the coal seam, the method for determining the porosity of the coal seam fracture by utilizing double lateral loggings, which is established according to a resistivity distribution range, is extremely high in pertinence; and the method has the advantage of stronger practical applicability.

Description

technical field [0001] The invention belongs to the technical field of geophysical exploration of unconventional oil and gas resources, and is mainly used for the identification of the fracture development degree of coalbed gas reservoirs and the calculation of the fracture porosity. Background technique [0002] Well logging is an important field of earth science and one of the important engineering technologies for oil and gas exploration and development of coalbed methane and other unconventional oil and gas resources. In the exploration and development of coalbed methane, the determination of the development degree of coalbed fractures and its parameters is of great significance. It not only involves the production of coalbed methane, water yield, etc., but also has important guiding significance for the later transformation of coalbeds and the production process of coalbed methane. However, due to the complex anisotropy and heterogeneity of coalbed methane formations an...

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Application Information

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IPC IPC(8): E21B49/00
Inventor 邓少贵范宜仁杨东根陈华
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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