Occurrence correction of bedrock structural plane in inclined hole imaging of underground oil storage

Abstract

During the investigation of underground oil storage, only the apparent inclination and apparent dip angle are obtained from the measurement of structural plane occurrence of the inclined hole in rock mass due to the angle between the reference system of the TV imager and the ground, which vary greatly from the actual conditions. Therefore, a correction formula for the structural plane occurrence of inclined hole was proposed based on the rotation matrix theory in combination with the characteristics of the borehole TV imager with constant true north direction, and the formula was verified with the geometric model and the engineering cases. Besides, the measurement results based on inclined hole imaging were corrected based on the actual investigation of an underground oil storage, and the occurrence area and the vertical variation characteristics of structural plane in the storage were revealed. The results show that the structural plane occurrence is quite different before and after correction, and the development of the structural plane after correction is consistent with the actual situation. Moreover, the apparent inclination and dip angle of the structural plane of inclined hole can be transformed into the true inclination and dip angle with the proposed correction formula, thereby greatly improving the precision of structural plane occurrence based on inclined hole imaging and effectively controlling the engineering error. Conclusively, the research results could provide theoretical evidence and data support to the evaluation on the surrounding rock stability, structural development and underground water seepage of the underground oil storage.

Keywords

• underground oil storage
• structural plane occurrence
• correction
• borehole tv imaging
• inclined hole
• rotation matrix theory