层叠法变速构造成图的地质基础及其应用

Application of layer-cakemethod tomake structuremap and geological base.

中国石油化工股份有限公司石油勘探开发研究院海外中心 北京100083

Petroleum Exploration and development research institute of SINOPEC, Beijing 100083, China

对于垂向速度突变的地层,采用速度连续变化的层状介质模型和平均速度场实现变速成图.会带来较大的误差。为此,探讨了采用分段速度模型描述速度场的层叠法变速构造成图方法。首先利用VSP、地震测井、声波测井等速度资料,根据速度变化趋势划分速度段,分段拟合速度,求取各速度段的截距(v₀)和斜率(K),建立各层v₀速度平面图;然后计算层速度,获得各速度段的层速度平面图;再利用各层的层速度和时间计算各层的厚度;最后通过多层厚度叠加,获得不同层段的构造图,实现变速成图。该方法不需要编制时间等值线图,因此避免了在成图过程中出现的相交点时间差异问题。

The velocity of seismic wave varies rapidly along both lateral and vertical direction in complex geologic condition.Flexible v₀-K (intercept-gradient) curvesmake it possible to reflect the variation of velocity.Relying on velocity data like VSP, acoustic log and well log data, v₀-K velocitymodel enable us to divide stratum into some layers with respective value of v₀ and K, thus the velocitymap of v₀ is established.Then the interval velocitymap is obtained by calculating interval velocity.Next, the thickness of each layer is estimated bymultiplying interval velocity with iso-chroa Finally, the depth of each layer is given by adding the thickness of this layer to the depth of its upper layer..Thismethod can erase timemistie without using T₀map.