基于微球形聚焦测井的地层裂缝定量评价方法

Quantitative Fracture Evaluation Method Using Microspherically Focused Logging Data

随着油田勘探程度提高,裂缝性储层逐渐成为勘探重点。微球形聚焦测井具有贴井壁测量、分辨率高的特点,比居中测量的电测井方法更适合刻画井周裂缝。建立含基岩、裂缝、井眼的裂缝性地层微球形聚焦测井正演模型;利用有限元法计算不同裂缝开度、延伸长度、充填流体电阻率、基岩电阻率条件下微球形聚焦测井响应,分析裂缝开度、延伸长度、充填流体电阻率及基岩电阻率对微球形聚焦测井响应的影响,归纳裂缝性地层微球形聚焦测井响应规律;根据正演结果建立了基于微球形聚焦测井的裂缝开度评价图版,通过对图版进行拟合,建立一套裂缝开度、孔隙度、密度评价方法。该图版在×井裂缝性砂岩地层中应用效果较好,证实了该方法的可行性。

Fractured reservoirs are becoming a focus as exploration goes on.A microspherically focused logging tool can record data immediately along well wall and the data recorded have high resolution,so it can describe the fractures around wellbore more effectively than the logging tools which record data in the center of the wellbore.First a forward model involving bedrock,fractures,a borehole and a microspherically focused logging tool is set up;then the finite element method is used to calculate the microspherically focused logging responses with different fracture openings,fracture lengths,fluid resistivity and bedrock resistivity,the influences of these factors on the logging responses are analyzed,and the response rules are summarized for fractured formations;and finally,based on the forward modeling results,a fracture opening evaluation plate based on microspherically focused logging data is established,as well as fracture opening,porosity,and density evaluation methods by fitting the plate.This plate has a good application effect in the fractured sandstone reservoir in well×,which confirms the feasibility of this method.