水淹层混合地层水宏观俘获截面逐层计算方法

 清污水交替注入型水淹层混合地层水矿化度变化较大.在进行脉冲中子类过套管剩余油饱和度测井解释时,地层水矿化度的多变性将导致地层水宏观俘获截面这一重要参数不易确定.对研究区块水淹层混合地层水的水型和矿化度进行了分析,分析结果表明不同小层间混合地层水矿化度变化较大,因而逐层计算混合地层水宏观俘获截面十分必要.本文以脉冲中子-中子测井评价为例,构建原始含油饱和度解释模型,对地层流体宏观俘获截面进行信息提取,提出了利用动静态测井资料确定混合地层水宏观俘获截面的方法.植入解释程序后,该方法可对同一解释层内水淹程度不一致的地方,分别计算出混合地层水宏观俘获截面.计算过程较好地考虑了层间差异性,提高了计算结果准确性,为利用动静态测井资料联合法对清污混注水淹层进行定量评价提供了思路.

Layer-by-layer Calculation of the Macroscopic Capture Cross Section of Mixed Formation Water in Water-flooded Zone

The salinity of the mixed water in the water flooded zones injected by the fresh water and the sewage has a great variation. As an important parameter in a remaining oil saturation calculation model in a cased hole, the macroscopic capture cross section of the mixed formation water is difficult to determine. The distribution of the salinity and solutes in the mixed formation water from the water flooded layer in the study area shows that it is necessary to calculate the macroscopic capture cross section of the mixed formation water layer by layer. Pulsed neutron-neutron well logging evaluation in the water-flooded zone is taken as an example in this paper. Firstly, the original oil saturation model is established. And then the macroscopic capture cross section of the formation fluid is determined. Finally, the macroscopic capture cross section of the mixed formation water is calculated based on the static and dynamic logging information. As the water flooding degree of some sampling points is inhomogeneous in the same layer, the method can also calculate the corresponding macroscopic capture cross section of the mixed formation water. The practical application shows that this method accurately reflects the variability of the salinity of the formation water. The calculation accuracy is improved because the difference between layers has been taken into consideration. This method also provides a new way for the quantitative assessment of the water flooded zones injected by the fresh water and the sewage by using some comprehensive methods to consider the dynamic and static logging data.