东濮凹陷低电阻率油层测井解释方法研究

Study of logging interpretation for low-resistivity sandstone reservoirs in Dongpu Depression

在东濮凹陷发现了一大批电阻率相对较低的油气层 ,经试油证明可以获得较高的油气产量 ,但用常规测井解释方法容易得出错误的解释结论。在分析东濮凹陷油气层低电阻率成因的基础之上 ,提出了测井评价方法。分析研究认为 ,地层水的矿化度高与束缚水含量高是形成东濮凹陷低阻油气层的主要原因。提出了适合于低电阻率油层的含水饱和度计算模型 ,该模型具有简单实用的特点 ;由实验分析资料 ,得到了计算束缚水饱和度、油水相对渗透率的方法 ;提出了将孔隙度与油水相对渗透率相结合划分油水层的方法。通过 2 0口井试油结果证实 ,这种低阻油层测井解释方法 ,利用油水相对渗透率来识别油水层 ,不仅具有解释更简单、更客观的优点 ,而且能大大提高低阻油层识别的成功率。

A great deal of low-resistivity reservoirs was found in Dongpu Depression. Though production tests on the reservoirs show high production, conventional logging interpretation often yielded contrary results. It was concluded that high salinity and high bound water saturation are the main causes for the formation of low-resistivity reservoirs. The author presented a model for calculation of water saturation in low-resistivity reservoirs, and a method to distinguish low-resistivity hydrocarbon-bearing reservoirs from water-bearing formations by combining porosity and relative permeability. The methods for calculation of bound water saturation and relative permeability were derived by laboratory data. Production tests in 20 wells showed that proposed methods are reliable, easy to use, and improve the success rate in identification of low-resistivity reservoirs greatly.