Mechanism of strain rate evolution in horizontally adjacent LF-DAS fiber-optic monitoring wells

ABSTRACT: Many different features of the strain rate data have been obtained from the field of Low Frequency Distributed Acoustic Sensing(LF-DAS) fiber-optic horizontal well monitoring, and the mechanisms behind these features are still in the exploratory stage. In order to explore the mechanism of strain rate evolution in horizontal fiber-optic monitoring wells,this paper firstly establishes a forward fiber-optic strain rate model based on the three-dimensional finite element method; secondly, the evolution of the strain rate under different height differences is simulated based on the model. The study reveals that, when the fracturing well and the monitoring well are parallel, the elevation difference between them significantly influences the evolution of the strain rate. The strain rate waterfall plot exhibits distinct features such as heart-shaped and X-shaped patterns, and the shape and extent of the blue zones representing negative strain rates on both sides also vary accordingly. Moreover, a strong correlation is observed between the elevation difference and the minimum width of the red band, which displays an approximately linear relationship when the fiber optic cable is positioned above the fracture plane.These results help to interpret fiber-optic data obtained from horizontal fiber-optic monitoring wells in the field.