Characterization parameters of the evolution degree of strike-slip faults

Abstract

Strike-slip faults and their related structures have great value for oil and gas exploration. Accurate understanding of the evolution degree of strike-slip faults is crucial to oil and gas exploration in strike-slip structural belts. Previous studies have had a qualitative understanding of the growth and evolution process of strike-slip faults, but there is still a lack of objective and quantitative basis to determine the evolution degree of strike-slip fault zone. The key is the lack of parameters that can characterize the evolution degree of strike-slip faults. In order to solve this problem, this paper, based on the independent physical simulation experiment of Riedel shear structure, collected plane images and carried out a statistical analysis of fault geometry parameters in strike-slip fault zone. By analyzing the corresponding relationship between the periodic change of plane structure and the change of geometric statistical parameters during the evolution of fault zone, the change law of geometric parameters during the evolution of fault zone is revealed, and a new understanding is proposed that the standard deviation of the angle data between adjacent faults in the same fault zone is taken as the characterization parameter of the evolution degree of strike-slip faults. The main conclusions are as follows: (1) The evolution degree of strike-slip fault zone is significantly related with the standard deviation of the angle data between adjacent faults in fault zone, and the plane structural style in different evolution degrees corresponds to the distribution interval of the standard deviation of the angle data between adjacent faults in fault zone; (2) According to the combination pattern of fault planes, the evolution stage of strike slip fault can be divided into shear unidirectional fracture stage, shear en echelon fracture stage, and shear connected fracture stage, and the corresponding standard deviation (S) of the angle data between adjacent faults in fault zone is 1 < S < 4, 4≤S < 8, and S≥8, respectively; (3) For the actual strike-slip fault zone, the evolution degree of strike-slip faults can be revealed by statistical analysis of the standard deviation of the angle data between adjacent faults in fault zone.

Keywords

• fault evolution
• angle between adjacent faults
• strike-slip fault
• physical simulation of structure
• oil and gas exploration