脉冲中子全能谱测井数据处理方法及影响因素的模拟研究

Simulation of Data Processing Method for Pulsed Neutron Whole Energy Spectroscopy Logging and its Influencing Factors

利用蒙特卡罗方法模拟不同条件下的非弹能谱,采用非弹能谱中的Si、Ca和C窗的伽马计数与O窗的伽马计数比值(SCCTO)确定地层含油饱和度。结果显示,在孔隙度一定的地层,SCCTO与含油饱和度近似成正比;随着孔隙度的增加,饱含水地层的SCCTO减小,而饱含油地层的SCCTO先略微下降然后再增加;井眼持水率不同,SCCTO不同;SCCTO受岩性的影响较小,而受泥质含量的影响较大。通过和C窗与O窗的伽马计数比(C/O)比较看出,在对岩性、孔隙度、井眼、泥质含量等作出相应校正后,利用SCCTO确定饱和度要比C/O具有优势,能更好地反映地层的油水性。

The inelastic scattering gamma spectroscopy under the condition of different formation was respectively simulated by using Monte Carlo method, and the formation oil saturation may be accurately determined according to the ratio （SCCTO） of the gamma counts in energy windows of Si, Ca and C to that in energy of O from inelastic scatter gamma spectroscopy. It is concluded that the relation between the SCCTO value and formation oil saturation is approximately linear when the porosity is fixed. The SCCTO value decreases when porosity increases in the formation filled with water, but that first decreases a bit and increases with porosity increasing in the formation filled with oil. The SCCTO varies with the borehole holdup changing, and it is somewhat affected by lithology but greatly affected by the shale content. It was advantageous to determine formation saturation by using SCCTO comparing with C/O when the corrections of porosity, lithology, holdup and shale content were accomplished. Therefore; the formation fluid character was better distinguished in accordance with SCCTO.