论文详情
为了提高羌塘盆地地震资料采集质量,早日实现该地区油气地球物理勘探突破,2015年在北羌塘坳陷、中央隆起带和南羌塘坳陷分别进行了常规可控震源、低频可控震源、大吨位可控震源、炸药震源激发试验及高密度、高覆盖宽线采集试验,取得以下认识:①最佳激发因素。常规可控震源振动台次为3台1次,驱动幅度为70%,扫描频率为6.0~84.0 Hz,扫描长度为18 s;低频可控震源振动台次为2台1次,驱动幅度为60%,扫描频率为1.5~84.0 Hz,扫描长度为16 s;大吨位可控震源振动台次为2台1次,驱动幅度为70%,扫描频率为6.0~84.0 Hz,扫描长度为16 s。炸药震源为单井高速层下7 m激发,最浅井深18 m,药量18 kg;组合激发方式为2口井×15 m×12 kg或3口井×12 m×8 kg。②尽管可控震源单炮的能量、信噪比、频谱及子波一致性与炸药震源相比并不占优,但可控震源激发在高密度高覆盖采集条件下仍能获得等同于或明显优于井炮激发质量的地震资料。③基于“环保、安全、经济、高效”考虑,羌塘盆地宜采用可控震源和井炮联合的高密度、高覆盖宽线采集方案,可控震源最佳观测系统为3L3S或2L3S,覆盖次数960次以上;井炮震源最佳观测系统为2L3S或3L2S,覆盖次数为300~360次。
In 2015,to improve the acquisition quality of seismic data in the Qiangtang Basin and make a breakthrough in hydrocarbon geophysical prospecting technology,we conducted a series of seismic acquisition tests on general vibroseis,low-frequency vibroseis,large-tonnage vibroseis,and explosive sources,as well as high-density and high-fold wide line profiling tests,in North Qiangtang Depression,Central Uplift Belt,and South Qiangtang Depression.The results were as follows:①The optimum exciting parameters for general vibroseis were as follows:the vibration pattern was of three diesels vibrating for one time,the drive level was 70%,the sweep frequency ranged from 6 Hz to 84 Hz,and the sweep length was 18 s.The optimum exciting parameters for low-frequency vibroseis were as follows:the vibration pattern was of two diesels vibrating for one time,the drive level was 60%,the sweep frequency ranged from 1.5 Hz to 84 Hz,and the sweep length was 16 s.The optimum exciting parameters for large-tonnage vibroseis were as follows:the vibration pattern was of two diesels vibrating for one time,the drive level was 70%,the sweep frequency ranged from 6 Hz to 84 Hz,and the sweep length was 16 s.The optimum exciting parameters for the dynamite sources were as follows:a single hole had a depth of 7 m below the high-velocity layer (or above 18 m in depth),charge sizes were 18 kg,and the combination array shooting pattern was two holes×15 m×12 kg or three holes×12 m×8 kg in areas with unfavorable surface conditions.②Although the energy,signal-to-noise ratio,bandwidth,and wavelet coherence of the shot record by the vibroseis were not as good as those of the borehole explosive,the quality of seismic sections obtained by the vibroseis using a high-density and high-fold acquisition technique might be equal to or superior to that of the borehole explosive.③Because it is an environmentally friendly,safer,more economical,and highly efficient operation mode,the high-density and high-fold wide line profiling acquisition technique,which is a combination of the vibroseis and the borehole explosive source,is much more suitable to the Qiangtang Basin.The layout chart by the vibroseis can be designed as 3S3L or 2L3S,with a minimum fold of 960 times.The layout chart by the borehole explosive can be designed as 2L3S or 3L2S,with the fold ranging from 300 to 360 times.
国土资源部陆域能源矿产地质调查计划西藏托纳木-笙根地区油气地质调查(［2015］01-01-01-002)、西藏隆鄂尼-鄂斯玛地区油气地质调查(［2015］01-01-01-001)、西藏半岛湖地区油气地质调查(［2015］01-01-01-003)项目联合资助。