Formation mechanism of vertical "long string beads" in carbonate reservoir
Sun Dong1, Pan Jian-guo1, Yong Xue-shan1, Han Jian-fa2, Zhang Hu-quan1, Gao Jian-hu1, Wang Hong-bin1
1. Northwest Branch,Research Institute of Petroleum Exploration&Development of Petrochina,Lanzhou City,Gansu Province,730020,China;
2. Petrochina Tarim Oilfield Company Research Institute of Petroleum Exploration&Development,Korla,XinJiang Autonomous Region,841000,China
Abstract：Regarding the carbonate reservoir in Tazhong Area,wave equation forward modeling were conducted and the finite difference algorithm was used to solve the wave equation in order to disclose the formation mechanism of vertical "long string beads".The study results show that the diffraction wave could be formed by single and big cave,vertical overlap cave,sliding fault and the formation composition,conducting migration imaging for the diffraction wave could form vertical "long string beads" reflection.For the double string bead formed by single cave,the different reflection coefficients between the top layer and bottom layer lead to a top string bead waveform,like two troughs and one peak,and a bottom string bead waveform,like two peaks and one trough.The double string bead formed by double caves is the two string beads with same reflection characteristics,it is easy to distinguish,the combination of strata and the sliding fault could result in the formation of several vertical string beads,the pre-assumption is that there should be obvious inner layers for the carbonate rocks,and the erosion should exist along the sliding fault.Those conclusions could be referred when studying formation mechanism of the complicated seismic response,understanding the geological mode and guiding the exploration and development.
