High-density beam seismic acquisition technique and its application on the Kashgar structural belt of the Tarim basin
Received date: 2024-05-23
Online published: 2025-05-09
Copyright
Due to the complex surface and underground geological conditions, the S/N ratio of the seismic records in the Kashgar structural belt of the Tarim basin is extremely low and the seismic imaging of the underground geological targets is very difficult, which affect the understanding of underground geology and restrict the process of oil and gas exploration in this area. After summarizing previous successful exploration experiences and shortcomings, a high-density beam seismic acquisition technology has been developed and achieved good application results. The near surface velocity model by tomographic inversion and the static correction have been improved after using single-sensor or small geophone-array receiving. The inline and crossline noises were evenly and adequately sampled and the S/N ratio of the pre-stack seismic data has been improved by 3D denoising, and finally the seismic imaging of the complex underground structures has been improved remarkably by high trace-density acquisition. Compared with the wide-line seismic acquisition, high-density beam seismic can better solve the problems of low S/N ratio of seismic record and difficult imaging of complex high-dip structures in the mountainous areas. Some favorable exploration targets have been discovered using the new seismic data, and an significant breakthrough in the Carboniferous-Permian carbonate rocks has been achieved after drilling the exploration well QT1, opening up a new era of oil and gas exploration in the southwestern depression of the Tarim Basin.
YiMou LIU , YaLin LI , Xu ZHOU , Ling FU , Yi ZHOU , WenSheng DUAN . High-density beam seismic acquisition technique and its application on the Kashgar structural belt of the Tarim basin[J]. Progress in Geophysics, 2025 , 40(2) : 511 -523 . DOI: 10.6038/pg2025II0060
表1 满足干扰波无假频采样的道距计算表Table 1 Receiver interval for non-aliasing sampling of the interference waves |
| 干扰波类型 | 面波1 | 面波2 | 折射波1 | 散射波1 | 散射波2 |
|---|---|---|---|---|---|
| 频率/Hz | 6~10 | 7~13 | 18~23 | 8~13 | 7~13 |
| 视波速/(m/s) | 740 | 1250 | 3900 | 800 | 780 |
| 视波长/m | 74~123 | 96~178 | 169~216 | 62~114 | 65~111 |
| 最大道间距/m | 37 | 48 | 85 | 31 | 33 |
图3 不同空间采样范围单炮数据F-K谱(a)最大偏移距=1185 m;(b)最大偏移距=1035 m;(c)最大偏移距=885 m;(d)最大偏移距=735 m;(e)最大偏移距=585 m;(f)最大偏移距=435 m. Fig 3 F-K spectrum of single shot data with different spatial sampling ranges (a)Maximum offset=1185 m; (b)Maximum offset=1035 m; (c)Maximum offset=885 m; (d)Maximum offset=735 m; (e)Maximum offset=585 m; (f)Maximum offset=435 m. |
图4 工区以往宽线不同覆盖次数叠加剖面对比(a)1炮1线,覆盖次数120次;(b)1炮2线,覆盖次数240次;(c)2炮2线,覆盖次数480次;(d)3炮2线,覆盖次数720次. Fig 4 Comparison of the stack sections by previous wide-line seismic with different fold (a) 1 shot line and 1 receiver line, fold 120;(b) 1 shot line and 2 receiver lines, fold 240; (c) 2 shot lines and 2 receiver lines, fold 480; (d) 3 shot lines and 2 receiver lines, fold 720. |
表2 检波器组合参数表Table 2 Geophone array parameters |
| 检波器类型 | 检波器型号 | 自然频率/Hz | 检波器个数 | 连接方式 | 等效灵敏度/(V/m/s) | 组合图形 | 组内距/m | 组合基距距/m |
|---|---|---|---|---|---|---|---|---|
| 模拟 | GS-30DX | 10 | 10 | 5串2并 | 100 | 正方形 | 2.5 | 5 |
图7 山体区横向不同基距组合接收对层析速度反演和静校正量计算的影响(a)初至时间误差;(b)层析反演高速层顶面深度误差;(c)静校正量误差. Fig 7 Effects of different crossline geophone array length on the velocity tomography and static calculation (a) First arrival time error; (b) Depth error of the top of the high-velocity-layer by velocity tomography; (c) Statics error. |
图9 山体区应用不同基距横向组合接收层析反演静校正量后的叠加剖面对比(a)应用横向5道组合(组合基距120 m)初至层析反演静校正量后的叠加剖面;(b)应用单道(组合基距5 m)初至层析反演静校正量后的叠加剖面. Fig 9 Comparison of the stack sections after static correction by different crossline geophone array length on the mountainous area (a) Stack section after static correction by tomography with crossline geophone array length of 120 m; (b) Stack section after static correction by tomography with crossline geophone array length of 5 m. |
图11 不同炮道密度叠前时间偏移剖面对比(a)炮点距30 m,炮线距120 m;(b)炮点距60 m,炮线距120 m;(c)炮点距120 m,炮线距120 m;(d)炮点距60 m,炮线距360 m;(e)炮点距120 m,炮线距360 m;(f)炮点距30 m,炮线距360 m. Fig 11 Comparison of the pre-stack time migration sections with different trace density (a) Shot interval of 30 m, shot line interval of 120 m; (b) Shot interval of 60 m, shot line interval of 120 m; (c) Shot interval of 120 m, shot line interval of 120 m; (d) Shot interval of 60 m, shot line interval of 360 m; (e) Shot interval of 120 m, shot line interval of 360 m; (f) Shot interval of 30 m, shot line interval of 360 m. |
感谢审稿专家提出的修改意见和编辑部的大力支持!
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