三探测器密度测井仪测量套管厚度和水泥环密度

Measuring Casing Thickness and Density of Cement Sheath with Three-detector Density Logging Tool

为研究套管井的套管厚度和水泥环密度测量,采用MCNP数值模拟软件进行了三探测器密度测井的基本理论研究、自然伽马能谱分析、套管厚度的测井响应分析,以及水泥环密度的测井响应分析,并建立合理的解释模型。确定计数率的主要影响因素、计数率与主要影响因素的函数关系以及三探测器密度测井仪测量套管厚度和水泥环密度的数据处理方法。进行测井数据处理时发现,无论地层条件如何变化,所得套管厚度值均较为准确,而要得到准确的水泥环密度值,水泥环厚度应大于2.5cm。通过在塔里木盆地大北克深地区计算套管厚度和水泥环密度,该方法取得了较好的效果。

Cased-hole logging is becoming the focus of the work in exploration and development in Dabei and Keshen of Tarim oilfield, and provides evaluation parameters for those wells with low borehole stability after installing case; it also provides measurement data for old wells which have data quality problems; we use cased-hole logging for reservoir dynamic monitoring as well. Therefore, Measurement of casing thickness and cenment density has practical meaning. Proposed is a method to measure casing thickness, the density of cement sheath, and the basic theories in cased-hole logging and analyzing gamma spectral from three-detector density logging tool using MCNP, thus determining the main influences on counting rate and establishing a relationship between counting rate and the main influences. We conclude that whatever happens in formation condition, the value of casing thickness is more accurate. However, to get the accurate value of the density of cement sheath, casing thickness should be greater than 2.5 cm. The method is better applied in Dabei ~ Keshen region.