Graptolite zone characteristic based shale isochronous stratigraphic well-logging dividing method and system

Abstract

The invention discloses a graptolite zone characteristic based shale isochronous stratigraphic well-logging dividing method and system. The method comprises the following steps: performing graptoliteidentification on a standard well, and determining the type of graptolite zones of a region in which the standard well is located; preliminarily determining the position of each graptolite zone according to each local peak value of a well-logging gamma curve for a fresh well of the region; and determining a semi-range value while each local peak value is reduced to the local smallest value or is increased to the local biggest value in an upward direction as an upper border of the graptolite zone which corresponds to the local peak value and a lower border of the graptolite zone above. The graptolite zone characteristic based shale isochronous stratigraphic well-logging dividing method can provide a fine and accurate division scheme for longitudinal and planar distribution of shale gas enriching high-yield intervals of different regions, effectively improves fineness and precision of the shale gas enriching high-yield intervals under an isochronal formation cor-relation framework, improves predication precision of a shale gas horizontal well target region, and provides reliable technical means for predication and evaluation of enriching high-yield intervals of shale gas explorationand development.

Description

Technical field [0001] The invention relates to the technical field of shale gas exploration and development, and more specifically, to a method and system for shale isochronous strata logging division based on graptolite zone characteristics. Background technique [0002] The Sichuan Basin and its surrounding Wufeng Formation-Longmaxi Formation shale gas reservoirs are currently the key areas for exploration and the main production areas. Two national shale gas demonstration areas have been built, Jiaoshiba and Weiyuan-Changning. This area has a good shale gas exploration potential. At present, shale gas exploration is mainly divided by lithology and logging curves. Due to the small differences in shale depositional environment, the geochemical characteristics, mineral characteristics and physical properties of shale have small differences in profile and plane. With continuous changes, this lithology division is difficult to distinguish the hydrocarbon generation capacity, rese...

AI Technical Summary

Problems solved by technology

The small number of coring wells limits the large-scale application of this technology, and the cost of coring is too high. The number of coring wells in development wells in shale gas development zones is small, but each well has a well logging curve, so It is necessary to establish methods and techniques to divide shale gas-enriched and high-yield intervals between graptolite belt characteristics and log curves, so as to improve the economy and effectiveness of shale gas-enriched and high-yield intervals

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