低电阻率油气层测井识别技术

LOGGING TECHNOLOGY OF IDENTIFYING LOW-RESISTIVITY HYDROCARBON RESERVOIRS

低电阻率油气层在我国各油气田均有分布 ,而且形成的原因也各有不同 ,原西南油气田分公司准南勘探区块的吐谷鲁构造安集海河组油气层属低电阻率油气层 ,其电阻率值普遍小于 10Ω·m ,与水层的电阻率差异很小。常规测井储层参数解释计算的含水饱和度往往偏大 ,很容易将油气层解释为水层。文章立足于测井资料 ,充分挖掘测井资料对低阻油气层识别的能力 ,对该地区吐谷 1、吐谷 2井砂岩储层的油气水性质采用电阻率特征判别法、三孔隙度重叠法、阵列声波能量法、纵横波时差法、声阻抗与声波时差重叠法、交会图法以及神经网络识别技术的合理组合进行了有效识别 ,提高了该地区低阻油气层解释准确性 ,就低电阻率油气层的测井识别方法进行了一些有益的探索。同时还为准确地进行低电阻率砂岩储集层的流体性质判别提出了相应的测井系列建议。

Low-resistivity hydrocarbon reservoirs have been found in many oil and gas fields in China and they are of various formation conditions. The Anjihaihe Formation hydrocarbon reservoir in Tugulu structure in Zhunnan exploration area belongs in the low-resistivity hydrocarbon reservoir with resistivities of < 10 Ω &middot m which makes little difference to those of water-bearing formations. The values of water saturation calculated through interpreting conventional log data are often on the large side, so that it is very easy to interpret the hydrocarbon reservoir as a water-bearing one. In order to give full play to the ability of identifying low-resistivity hydrocarbon reservoirs by log data, the properties of fluids in the sandstone reservoirs found in wells Tugu - 1 and Tugu - 2 in this area were effectively identified by use of a reasonable assemblage of resistivity character discrimination, three porosity overlapping, array sonic energy, compressional-shear wave interval transit time, overlapping of acoustic impedance with sonic interval transit time, crossplot method and nerve network method, etc., through which the accuracy of interpreting low-resistivity hydrocarbon reservoirs in the ares is raised. This is a beneficial exploration for identifying the low-resistivity hydrocarbon reservoirs by log data and a suggestion on relevant logging system is also provided for accurately identifying the properties of fluids in the low-resistivity sandstone reservoirs.