Characterization of Hydraulic Fractures in Tight Conglomerate Reservoirs in Baikouquan formation, Mabei Slope

摘要/Abstract

摘要： Hydraulic fracturing is a main technique for developing oil and gas in tight conglomerate reservoirs. Currently, hydraulic fractures are mainly studied by means of physical experiments and numerical simulation. The study results can provide a theoretical basis for optimization of development plans, but they are not verified with field data, bringing great uncertainties to the design of stimulation measures. In order to describe the shape of hydraulic fractures for confirming the effective stimulation in tight conglomerate reservoirs, a coring well was drilled on the north slope of Mahu sag for obtaining hydraulic fractures. Based on the observation and analysis of the tight conglomerate cores, the shape, occurrence, and density of hydraulic fractures were characterized by using the core, image logging and CT scanning data. It is found that the tight conglomerate is characterized by large grain size, poor sorting, grain support, and strong heterogeneity. A total of 335 hydraulic fractures were identified in the core with the length of 323 m. Principal fractures propagate in the direction perpendicular to the wellbore; branch fractures are few and nearly perpendicular to the main fractures; crushed zones and asymmetrical double-wing fractures are observed in some intervals. The fractures propagate in two modes: gravel bypassing and gravel penetrating, which are formed due to tension and shear action, respectively, and are thus classified as tensional fractures and shear fractures. The tensional fractures and shear fractures are consistent in occurrence, both with a high dip angle close to 90° and a nearly south-north trending. The density of shear fractures is generally greater than that of tensional fractures.

关键词: Mabei slope, Baikouquan formation, tight conglomerate, hydraulic fracture, fracture characterization, fracture shape, occurrence, density

Abstract: Hydraulic fracturing is a main technique for developing oil and gas in tight conglomerate reservoirs. Currently, hydraulic fractures are mainly studied by means of physical experiments and numerical simulation. The study results can provide a theoretical basis for optimization of development plans, but they are not verified with field data, bringing great uncertainties to the design of stimulation measures. In order to describe the shape of hydraulic fractures for confirming the effective stimulation in tight conglomerate reservoirs, a coring well was drilled on the north slope of Mahu sag for obtaining hydraulic fractures. Based on the observation and analysis of the tight conglomerate cores, the shape, occurrence, and density of hydraulic fractures were characterized by using the core, image logging and CT scanning data. It is found that the tight conglomerate is characterized by large grain size, poor sorting, grain support, and strong heterogeneity. A total of 335 hydraulic fractures were identified in the core with the length of 323 m. Principal fractures propagate in the direction perpendicular to the wellbore; branch fractures are few and nearly perpendicular to the main fractures; crushed zones and asymmetrical double-wing fractures are observed in some intervals. The fractures propagate in two modes: gravel bypassing and gravel penetrating, which are formed due to tension and shear action, respectively, and are thus classified as tensional fractures and shear fractures. The tensional fractures and shear fractures are consistent in occurrence, both with a high dip angle close to 90° and a nearly south-north trending. The density of shear fractures is generally greater than that of tensional fractures.

Key words: Mabei slope, Baikouquan formation, tight conglomerate, hydraulic fracture, fracture characterization, fracture shape, occurrence, density

LI Xiangyang, JI Hancheng, BIAN Tengfei, CHEN Liang, CHEN Liang, GUO Xinshu, LI Mengkai. Characterization of Hydraulic Fractures in Tight Conglomerate Reservoirs in Baikouquan formation, Mabei Slope[J]. 新疆石油地质, 2023, 44(zk(English)): 105-110.

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