Journal of Geology & Geophysics
Open Access
ISSN: 2381-8719
+44 1478 350008
ISSN: 2381-8719
+44 1478 350008
Hamdy H Seisa
Posters-Accepted Abstracts: J Geol Geosci
Every reliable interpretation method of shallow refraction seismic travel time data (also known as first arrivals or head waves) has to include criteria for distinguishing between vertical and horizontal variations of velocities. The Common Refractor Element (CRE) method presents a simple approach to interpret shallow refraction seismic data, especially in cases of piecewise lateral changes along the refracting interfaces. In this method, a common linear travel time element, (or part of it), which corresponds to a linear common refractor element is used for inversion of these first arrivals. Linear travel time elements are defined as linear parts of the travel time curve with equal slopes and consequently equal apparent velocities. Travel time parameters such as the layer reciprocal time, the apparent refractor velocity and the intercept time values are used to distinguish between vertical and horizontal variations. Layer reciprocal time means that the forward and reversed travel time refracted from one layer must be equal at the two ends of the travel time curve. Lateral changes in dip and/or velocity along the refracting interface create a travel time curve of different linear segments and the extrapolation of corresponding travel time elements for reversing profiles are not equal at both ends of the travel time curve, except for the last two refractor elements that represent the last two elements from each side of the refractor. Apparent refractor velocity can be used in several ways as another parameter for lateral variation or structure identification. In-line reversed profiling technique is essential for the required data.