川中地区奥陶系宝塔组石灰岩地震道信息分析

SEISMIC TRACE ANALYSIS OF BAOTA LIME STONE OF ORDOVICIAN IN CENTRAL SICHUAN

川中—川南过渡带是四川盆地天然气勘探的重点战场之一，位于乐山—龙女寺古隆起川中部分，面积约７ ０００ ｋｍ２ 。区内现今构造平缓，翼部倾角一般１°～５°，褶皱幅度与闭合度较小，断层不发育，常规地震勘探效果不佳。为此研究中主要采用了Ｆ—ＬＯＧ方法，完成了对该过渡带１９ 条（２４ 段） 地震水平叠加成果的拷贝加载，１０条（１２ 段） 测线上４４ ０６４ 个ＣＤＰ点的Ｆ—ＬＯＧ 和剩余Ｆ—ＬＯＧ剖面的计算、对比及解释工作，剖面总长度７１８．１３５ｋｍ ；还进行了测线经过的女基井、合１２、磨深１ 、广参２ 和涞１ 等五口井的地震道分析及地质层位的标定工作。通过研究发现并证实了王家场构造的存在，该构造上的奥陶系宝塔组石灰岩尖灭体朝北向上倾方向尖灭，与构造形成复合型圈闭。

Central Sichuan South Sichuan intermediate zone is one of the priority regions of natural gas exploration in Sichuan Basin,being located at the Central Sichuan portion of the Leshan Longnusi ancient uplift and being of an area of about 7 000 km 2.In this area,the existing structures are gentle,being of a flank dip at angles of 1° to 5° in general,small fold amplitudes and closures,and undeveloped faults.Therefore the results were not good in conventional seismic exploration.For this reason,the F LOG method was mainly adopted in the investigation and the copying and load carrying of the seismic horizontal stacking results of 19 lines (24 sections) and the calculation,correlation and interpretation of the F LOG and residual F LOG profiles of 44 064 common depth points on 11 lines (12 sections) were achieved,these lines with a total length of 718.135 m passing through the intermediate zone.The works of seismic trace analysis and geological horizon calibration of the five wells,i.e.Longnusi key well,well He 12,well Moshen 1,well Guangcan 2 and well Lai 1,passed through by the seismic lines were carried out.In light of investigation,the Wangjiachang structure was found and proved,the Baota limestone of Ordovician in the structure pinching out toward updip direction in the north to form a combination trap with the anticlinal structure.