叠前地震流体识别技术在碳酸盐岩缝洞型储层中的应用

针对塔河油田外围地区深层碳酸盐岩缝洞储层流体识别的问题,首先基于实际测井数据,通过井旁地震道集分析与岩石物理建模,分析了研究区地震AVO反射特征,在此基础上开展了AVO截距梯度积(P×G)属性分析、频变AVO反演、流体因子反演等方法试验,通过测井数据交汇、井旁地震道反演、地震与测井解释综合分析等综合评价,评价了采用AVO属性分析、频变AVO反演流体因子反演等单一方法识别本区目标储层流体具有一定的效果;然后,基于最小二乘方法以测井、钻井解释结果(漏失、油气解释成果)作为期望输出数据,通过求解超定方程组,给3种地震属性赋予不同权值,获得研究区缝洞储层油气综合识别结果,提高了碳酸盐岩缝洞储层含油气性识别可靠性;最后,在多数据融合及阈值判定的基础上,对工区每一口井位置的异常体积进行统计,将统计结果与井稳产日产量进行对比分析,结果表明,两者相关系数达到0.77,实现了缝洞储层流体定量识别。建立了应用流程,分析了方法应用关键参数。研究结果证明了叠前地震流体识别技术在碳酸盐岩缝洞型储层中流体识别的有效性,为类似地区流体识别提供了依据。

Application of pre-stack seismic fluid identification to carbonate fracture-cavity reservoirs

In this work,a protocol for fluid identification in deep carbonate fracture-cavity reservoirs in the peripheral area of the Tahe Oilfield was proposed.First,based on actual logging data,the seismic AVO reflection characteristics were analyzed through seismic gather and rock physics modeling near the wells.On the basis of this,three methods,namely,the AVO intercept gradient product(P×G)attribute analysis,frequency-varying AVO inversion,and fluid factor inversion were conducted.The logging data and the inversion of the seismic traces near the wells were analyzed comprehensively,to demonstrate the effectiveness of aforementioned single method for target fluid identification.The least square method was then utilized,using logging and drilling interpretation results(loss,oil and gas interpretation results)as the desired output data,to solve the overdetermined equations,so as to assign different weights to the three seismic attributes.The oil and gas in the fractured-cavity reservoirs was then identified.Finally,on the basis of the data fusion procedure highlighted above and after setting a threshold value,the abnormal volume of each well was quantified.The correlation coefficient of the statistical results and daily production data of steady wells reaches 0.77,which represents a quantitative identification of fracture-cavity reservoir fluids and serves as a confirmation of the validity of the pre-stack seismic fluid identification technique in carbonate fracture-cavity reservoirs.The implementation process and key parameters were also discussed in this paper.The proposed method provides a reference for fluid identification in carbonate fracture-cavity reservoirs.