不同韵律性油层水淹层测井定性识别方法

QUALITATIVE IDENTIFING METHOD OF WATERED-OUT OIL RESERVOIRS WITH VARIOUS RHYTHMS BY WELL LOGGING

水淹层测井识别是利用测井资料对水驱油藏水淹所发生的变化进行判断，弄清水淹部位和水淹程度，为油田开发调整挖潜工作提供依据.大庆喇、萨、杏油田早期注入淡水后改污水回注，油层水淹后储层电阻率基本呈“L”型下降的变化规律，应用电阻率和孔隙度测井曲线重叠法，可以通过分析储层的孔隙度和电阻率测井曲线间波形变化的特征，实现对储集层水淹信息的提取。通过引入曲线相对重心、椭圆度、饱满系数3个参数，结合不同韵律油层的地质特点和水线推进特点，对水淹前后的电阻率和孔隙度测井曲线进行重叠对应分析，建立了4种沉积韵律油层的水淹模型。应用该方法与密闭取心资料分析结果对比表明，电阻率和孔隙度测井曲线重叠法在定性识别水淹层方面是可行的，具有快速、直观的特点。

Watered-out oil reservoir identification by well logging is to diagnose the changes of waterflooded reservoirs with logging data, to locate the watered-out position and to investigate the watered-out degree and provide ref- erences for development adjustment. Fresh water injection at early stage in La-Sa-Xing Oilfields has been alternated by produced water re-injection, since then, the resistivity of watered-out oil layers declines and the declination fol- lows the rule of figuring like ＂ L＂. By overlapping resistivity and porosity logging curves, the distinctions of wave shape variations between porosity curves and resistivity curves can be captured and analyzed, hence hints on the watered-out reservoirs can be extracted. By adopting 3 parameters of curve relative cg （ center of gravity ） , elliptic degree and plumpness coefficient and considering geologic features of various rhythm reservoirs and water front ad- vancing within it, water-flooding models for 4 types of sedimentary rhythm reservoirs have been established through overlapping and analyzing resistivity and porosity curves before and after water-flooding. Comparison of the results done by the new method with those obtained from sealed core data indicates that the watered-out reservoir identification by overlapping method of resistivity and porosity curves is feasible and this method is efficient and illustrative.