等时界面处砂体地震响应特征分析
Analysis of Seismic Response Characteristics of Sand Body at Isochronous Interface

随着油气勘探开发技术的不断深入，油田开发的精度要求越来越高。识别有效储层，加深对有效储层分布范围和分布规律的认识是十分必要的。正演模拟是对一定的地质、地球物理问题作适当简化，形成数学模型，通过数值计算获取地震响应的过程，是解释储层性质的有效手段，能够帮助开发地震人员快速认识地震资料。本文针对P油田目标区块砂体横向变化快，叠置现象多样，地震响应特征不清等问题，在精细分析三维地震资料的基础上，结合该区钻井、测井及地质综合解释等资料，建立两套正演模型。首先论证了上层地震振幅能量减弱是由于下层砂体对其的影响，排除上部储层横向突变的情况。其次论证了上层储层为偏泥质砂层才会受下层砂体影响，振幅能量减弱，从而应用负振幅属性预测砂体的展布范围。对根据实际资料建立的地质模型进行正演，可以得到一定的规律，提高地震人员对地质体的认识，从而在砂体描述中提供一定的指导。
With the development of oil and gas exploration and development technology, the development of oil field requires more and more precision. In order to identify effective reservoirs, it is necessary to deepen the understanding of subsurface media. Forward modeling is the process of simplifying a specific geological or geophysical problem, forming a simplified mathematical model, and obtaining the seismic response by means of numerical calculation. It is an effective means to explain the reservoir characteristics and to help geophysicists understand the seismic data quickly. In this paper, the sand bodies in the target block of P oilfield change fast in transverse and have various superposition phenomena. So seismic response characteristics are ambiguous. Therefore two sets of forward modeling are established based on the analysis of 3D seismic data, the data of drilling and logging and comprehensive geological interpretation. Firstly, it is proved that the energy attenuation of the seismic amplitude of the upper layer is due to the influence of the lower sand body, excluding the lateral mutation of the upper reservoir. Secondly, it is proved that the upper reservoir is an argillous sand layer, affected by the lower sand body, and the amplitude energy is weakened. The forward modeling of the geological model based on the actual data can obtain certain rules and improve the understanding of the geological body, providing some guidance in the description of the sand body.