纵波方位各向异性及其在裂缝检测中的应用

P-wave azimuthal anisotropy and its application in detection of fractures.

1. 吉林大学地球探测科学与技术学院,吉林长春130026;2. 中国石油化工股份有限公司石油勘探开发研究院南京石油物探研究所,江苏南京210014

College of GeoExploration Science and Technology, Jilin University, Changchun 130026, China

裂缝型储层具有良好的油气储集性能,地球物理通常利用多波多分量技术来检测裂缝的方向和密度,但该技术的应用受到诸多因素的限制,因此,人们开始探索利用三维纵波资料进行裂缝预测的方法,但方位各向异性介质中P波反射系数的精确解很复杂。为此,首先通过物理模拟实验,证实垂直裂缝存在方位各向异性特征 (AVA);然后在AVA特征分析基础上,提出了基于二维多方位预测的精确解法和基于三维多方位预测的最小二乘法。利用基于三维多方位预测的最小二乘法,对塔河油田某区块的碳酸盐岩裂缝储层进行了预测,结果表明,预测的裂缝方向和密度与实际情况相符合。

Fractured reservoir is an important reservoir of hydrocarbon. The carbonate fractured reservoirs in Tahe Oilfield, western China and the tight sandstone fractured reservoirs in the west of Sichuan are favorable reservoirs for hydrocarbon accumulation. We verified the presence of vertical fractures results in azimuthal anisotropy by physical modeling. Based on an analysis of the characteristics of azimuthal anisotropy (AVA analysis) , we developed an analytic resolution of 2-D azimuthal prediction and a least square method for 3-D azimuthal prediction. These methods have been used in prediction of carbonate fractured reservoirs in Tahe Oilfield. The results show that the predicted fracture orientation and density are well agreement with the geology. AVA analysis provides prediction and description of fractured reservoirs with an effective way.