A method for predicting the abrasiveness of different drilling directions in shale formations

Abstract

The invention relates to a method for predicting the abrasiveness of a shaly stratum in different drilling directions. The method comprises the following steps: (1) measuring the internal friction angles and the sonic characteristic parameters of shale samples in different drilling directions; (2) building the relation models between the internal friction angles and the sonic time differences of the shale samples in different drilling directions; (3) building the relation models between the sonic time differences of the shale samples and the sonic time differences in the direction perpendicular to bedding planes as well as between the sonic time differences and drilling angles; (4) building the relation models between the internal friction angles of the shale samples in different drilling directions and the sonic time differences in the direction perpendicular to the bedding planes as well as between the internal friction angles and the drilling angles; (5) obtaining the logging data of on-site shale and performing back calculation to the sonic time differences of the shale in the direction perpendicular to the bedding planes; and (6) according to the relation models between the internal friction angles and the sonic time differences in the direction perpendicular to the bedding planes as well as between the internal friction angles and the drilling angles, determining the internal friction angles of the on-site shale in different drilling directions. The determined internal friction angles are the abrasiveness in corresponding drilling directions. The method can evaluate the abrasiveness of the shaly stratum in different drilling directions by virtue of the on-site sonic logging data and is convenient to use on site.

Description

technical field [0001] The invention belongs to the field of petroleum drilling, and in particular relates to a method for predicting abrasiveness in different drilling directions of shale formations. Background technique [0002] In the fields of oil exploration, extraction, and the like, well drilling is widely performed. Drilling is the process of drilling into rock formations using a drill bit. During the drilling process, the drill bit becomes blunt due to the wear of the rock and needs to be replaced after a period of use. The abrasiveness of the rock is an important factor affecting the wear of the drill bit. For shale formations with obvious bedding anisotropy, it is of great significance to accurately grasp the abrasiveness of different drilling directions in drilling engineering, such as bit selection, drilling parameter optimization, and directional wellbore trajectory optimization design. . [0003] Abrasiveness of rock is the ability of the rock to wear away...

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Problems solved by technology

[0004] These methods are all indoor experimental methods, and there are many problems, such as: ① The obtained results are difficult to reflect the high temperature and high pressure environment of the rock underground; ② It is difficult to fully reflect the change of rock properties in heterogeneous formations; The data measured in areas with large lithology changes may lack contrast; ④ It is difficult to establish a continuous section of rock abrasiveness in the area, and it is difficult to obtain rock abrasiveness data in different drilling directions; ⑤ It costs a lot of manpower, material resources and funds

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