本研究提出一個新的「毋需摘取初達波到達時間」之折射波靜態修正方法，即延遲時間差值法（Differential Delay Time，DDT）來處理CDP反射震測資料的風化層靜態修正。此為結合延遲時間與ABCD法之觀念所發展出的一個新方法，主要利用二相鄰測站B與C之初達折射波漣之相關函數（cross-correlation），求取二測站間之折射波相對走時差，取代以往傳統必須挑取初達波到達時間的繁雜過程，並且利用CDP資料的多重合特性，建立超波線（super trace），來計算相關函數及推算出相對走時差，此超波線計算不但可以減少因資料不佳所引起之誤差，且可利用偵錯機制，求得較為可信的走時差。 與傳統正負法（或ABC法）一樣，DDT法同樣也使用走時差的公式來直接求取各測站下的構造訊息，此法有效的結合雙邊炸之觀念（Reciprocal method），將所有差值植入相關矩陣，運用逆推方法分別計算折射層速度和風化層厚度，獲得風化層模型，再用以計算風化層靜態修正。本方法之特點在於毋需摘取初達波到達時間，不但可減少人為參與，增加問題之客觀性，其理論及實用性均有獨特之處。經過若干理論模型測試，証實本法正確。另外，亦採用一組具有嚴重風化層問題的淺層反射震測資料，經過淺部風化層靜態修正後，表現出更正確的深部地層構造影像，證實DDT法對起伏甚烈的地形處理效果極佳。 DDT法結合震測法中之折射及反射二大體系，在理論上，簡潔的將折射之核心觀念：延遲時間，與反射之CDP多重合之特性結合起來。在實作上，可以不需太多人為參與，由大量走時差資料自行在速度及深度二項來回做線性逆推，客觀且方便。我們已將該法納入正常的淺層反射震測資料處理，其所呈現結果出奇的好，很值得推廣使用。 ABSTRACT A differential delay time (DDT) concept is proposed for refraction static correction without picking first arrival times in the CDP reflection data processing. This new method is a modification of the ABCD method; it uses cross-correlation to measure the first arrival time difference between signals received at stations B and C, instead of directly computing them from their picked times. By taking advantage of multiple-fold CDP data, we apply the super trace measurement, which may alleviate the effect of data imperfections. As alike as the ABC method, we fill the traveltime differences in a matrix with the reciprocal method concept in DDT method, then the matrix is inverted to solve for the refraction velocity and weathering depth by a inversion method. Finally, we can get the static correction value converted by the refractor model. A synthetic model and a real case with a severe weathered layer problem have been tested to evaluate the method. Stable and manageable computation processes have been explored to attain maximum performance. The results are quite satisfactory. In the theory, the DDT method combines “delay time” concept of refraction with multiple fold of CDP data. In application, we can handle the data with DDT method automatically. This is very objective and convenient. Now we apply the DDT method to general shadow CDP seismic reflection cases and the results are very good. This method is worth using widely.
