二连盆地火成岩地区地震勘探采集方法研究与应用

Seismic data acquisition in the igneous rock area of Erlian Basin

1. 东方地球物理公司华北物探公司,河北任丘 062552;2. 中国石油华油田地球物理勘探研究院, 河北任丘 062552

An Xueyong, Huabei Geophysical Prospecting Company of BGP, CNPC, Renqiu 062552, China

二连盆地内许多地区的地表有大量火成岩分布,这些速度高、形状不规则的火成岩,极大地影响了地震勘探的施工效率和资料质量,制约了对下伏油气藏的认识。通过地表露头调查和小折射表层结构调查,基本了解了朝克乌拉凹陷和塔南凹陷的火成岩分布范围、岩层厚度和地震波速度等参数,研究了影响资料品质的主要因素。在此基础上,采用以可控震源为主、井炮为辅的激发方式,通过选取最佳的激发岩性、增加可控震源的振动次数和扫描长度、加密炮点等措施,改善了火成岩区的资料质量,新采集资料的信噪比和分辨率得到了明显改善,资料模糊区的范围减小,火成岩体的轮廓清楚,取得了良好的钻探效果。

Igneous rocks are distributed widely in the near surface in Erlian Basin. These rocks sharply decrease the efficiency of seismic data acquisition and degrade the acquired seismic data quality, which in turn impedes the detection of subsurface hydrocarbon reservoirs. With outcrops and refraction near-surface investigation, we determined the distribution range, thickness, and seismic velocity of the igneous rocks, and analyzed the main factors that affect the quality of seismic data. Several measures are adopted in the seismic data acquisition, including using vibrator as main seismic source supplemented by shot in holes, selecting suitable shooting rocks, increasing the vibration number of vibrator and sweep length, and narrowing the spacing of shot points. The new data are superior to the old ones in S/N, resolution, and the definition of igneous rock bodies, and smearing areas in sections become smaller.