Formation fracture logging evaluation method based on array sound wave amplitude attenuation

Abstract

The invention discloses a formation fracture logging evaluation method based on array sound wave amplitude attenuation. The method comprises the following steps: 1) collecting waveform amplitude data of longitudinal waves, transverse waves and stoneley waves of array sound waves of a well to be evaluated in a work area; 2) respectively calculating the average amplitude of the waveform amplitudes of the three waveforms; 3) selecting an average amplitude value of three waveforms of a compact layer section with non-developed cracks as a basic value; 4) respectively calculating the ratio of the average amplitude of the three waveforms to the base value; 5) calculating the comprehensive relative amplitude R of the three waveforms by using arithmetic average, and calculating the crack confidence sigma by using the product of the relative amplitude of the three waveforms; (6) drawing a work area evaluation map, and comprehensively evaluating the development result of the to-be-evaluated well crack by combining the comprehensive relative amplitude R and the crack confidence coefficient sigma calculated in the step (5); and 7) outputting a crack evaluation result. The evaluation method is simple, visual, low in cost, good in accuracy and reliability, high in practicability and wide in application range.

Description

technical field [0001] The technical field of the invention is the exploration and development of fractured oil and gas reservoirs, and in particular relates to a logging evaluation method for formation fractures based on array acoustic wave amplitude attenuation. Background technique [0002] Fractures play an important role in rocks, not only as pore fluid channels, but also as reservoirs. The existence and development of fractures in rocks make many kinds of rocks become reservoirs, including carbonate rocks, igneous rocks, metamorphic rocks, and tight sandy mudstones. Even in sandstone reservoirs with low porosity and low permeability, the existence of fractures has a great impact on the reservoir. Therefore, it is of practical significance to carry out identification and evaluation of fractures in fractured reservoirs. [0003] Currently, commonly used fracture evaluation methods include fracture observation and description based on cores, outcrops, and thin sections,...

AI Technical Summary

Problems solved by technology

However, at present, there is no clear limit value for the degree of amplitude attenuation in identifying fractures by the array acoustic wave amplitude attenuation method, and there is a lack of evaluation on the reliability of fractures.

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