洞穴充填程度的声波测井数值模拟与定量评价

Acoustic Logging Numerical Simulation and Quantitative Evaluation of Cave Filling Degree

洞穴型储层已成为碳酸盐岩油气藏稳产、增产的主力储集层之一.洞穴型储层的充填程度是影响该类储层储集和渗流特性的关键因素.但由于洞穴储集空间及其充填程度的复杂多变,使得声波测井对洞穴型储层的响应规律反应不清楚,严重制约了运用常规测井资料对该类储层的有效评价.本文利用数值模拟的方法对洞穴型储层在声波测井曲线上的响应规律进行研究,通过建立不同的地层模型,利用交错网格的有限差分方法对波动方程进行数值求解,并采用STC相关分析法提取纵横波时差,对洞穴的不同充填程度进行了数值模拟.模拟结果表明,洞穴的不同充填程度在声波模拟曲线上存在明显的响应特征,它们之间具有很好的对应关系,且呈现出一定的规律性,将其规律应用于实际测井资料的解释中,可为碳酸盐岩洞穴型储层充填程度的测井定量评价提供理论依据.

Cavernous reservoir has become one of the main reservoirs to keep stable and increasing production for carbonate reservoir.The filling degree is the key factor which affect the storage and filtration characteristics.However,due to complexity of the caves space and filling degree in the caves,the response laws of acoustic logging for the cavernous reservoir can＇t be reflected so clearly,and that the effective evaluation of the reservoir by using conventional well logging data has been severely restricted.Numerical simulation was used to study the acoustic logging response in cavernous reservoir.Through building up different simulation models,it utilized finite difference method of cross grid to get the wave equation＇s arithmetic solution,and used STC method to extract the slowness of compression and shear wave.The numerical simulations of cave filling degree were achieved,which indicated that the cave filling degree showed obvious response feature in the sound wave simulation curve.There is a good corresponding relationship between the two of them.This results will offer theoretical guidance to logging evaluation of cave filling degree in carbonatite cavernous reservoir.