Penerapan Koreksi Statik Refraksi Tomografi Seismik 2d Area Vulkanik

Akuisisi data seismik pada area dengan geologi vulkanik umumnya memiliki permasalahan, salah satunya adalah ditemukannya heterogenitas Velocity yang tinggi secara lateral maupun vertikal. Hal tersebut menyebabkan suatu gangguan di mana pola kemenerusan reflektor pada data rekaman seismik mengalami undulasi yang mengurangi kualitas data. Untuk mengatasi masalah tersebut, dapat diterapkan koreksi statik seismik dengan menggunakan inversi traveltime tomography, sebuah metode inversi tomografi refraksi seismik. Kemampuan metode inversi traveltime tomography untuk memetakan geologi dekat permukaan yang kompleks dinilai sesuai untuk mengatasi masalah tingginya heterogenitas Velocity. Pada penelitian ini, dilakukan pengolahan data seismik 2D dengan studi kasus data di area vulkanik Majalengka. Pengolahan data seismik dilakukan hingga tahapan Velocity stack, di mana dilakukan perbandingan antara data seismik dengan koreksi statik hasil inversi linier dan data seismik dengan koreksi statik traveltime tomography. Untuk mendapatkan model Velocity hasil traveltime tomography yang akurat dengan realita, diperlukan input first arrival time yang sesuai. Pengolahan data seismik dilanjutkan dengan melakukan Velocity Analysis pada ketiga penampang seismik, dan stack. Setelah analisa Velocity dilakukan pada ketiga variasi, diamati perbandingan semblance dan kemenerusan reflektor hasil stack. Dari pengamatan semblance yang dilakukan, terutama pada pengamatan di CMP 2575, isolasi pada amplitude lebih terlihat pada data seismik yang telah diterapkan koreksi statik traveltime tomography. Pengamatan kemenerusan reflektor seismik didapatkan yang paling terlihat berada di kedalaman 1500ms hasil koreksi statik traveltime tomography. Hasil penelitian menunjukkan bahwa penerapan koreksi statik menggunakan traveltime tomography meningkatkan kualitas hasil penampang seismik dalam kasus geologi vulkanik dengan heterogenitas Velocity pada permukaan. =============================================================================================== Seismic data acquisition on an area with volcanic geology commonly have problems, one of them is the existence of heterogenous rock Velocity on horizontal or vertical manner. That condition causes disturbance where seismic reflector continuity on the recorded data have some zigzaging which reduce the data quality. To overcome the problem, static corrections can be applied on the data using traveltime tomography inversion, a refraction tomography inversion method. The ability of traveltime tomography inversion method to image the complex near surface geology considered appropriate for solving the highly heterogenous Velocity problem.In this research, seismic 2D processing is done with data study case on a vulcanic geology area in Majalengka. The seismic data procesing is done to the step of Velocity stack, where analysis of the data quality is done by a comparison of seismic data with linear inversion static correction and seismic data with traveltime tomography inversion static correction. To get the Velocity model from the traveltime tomography that is accurate with real geology, a good first arrival input data have to be appropriate. The processing of seismic data then continued by doing Velocity Analysis followed by data moveout and stack on three variation of seismic data that is: without static, with GLI static, and with traveltime tomography static correction. After doing Velocity Analysis on the three variations, semblance and reflector continuity from stack is observed. From the analysis of semblace that is done on CMP 2575, semblance amplitude isolation are better shown on the seismic data which applied static correction with traveltime tomography inversion. The seismic reflector continuity analysis shown the best on the seismic data which using traveltime tomography static correction, observed on depth of 1500ms. This research shown that the application on static correction using traveltime tomography increase the quality of seismic image result on the case of vulcanic geology that suffers heterogenous near surface Velocity