镅铍源硼中子γ测井的可行性

为降低测井成本,用镅铍源取代脉冲中子源,研究在储层已注入硼酸溶液的条件下进行中子γ测井即硼中子γ测井的可行性。用Monte-Carlo模拟技术即通用程序MCNP(3B),计算了该测井方法的俘获γ能谱、俘获γ计数与含水饱和度及源距的关系。得出了俘获γ计数随含水饱和度的增加呈指数规律衰减;井眼对俘获γ计数的影响很小,而且俘获γ计数与地层孔隙度具有良好的相关性。从计算结果看,用镅铍源取代脉冲中子源进行硼中子γ测井是可行的,其适应性强,成本低。

Boron neutron-gamma logging with an Am/Be source

This paper investigates the feasibility of using a neutron-gamma log with an americium-beryllium source instead of a pulsed-neutron source to reduce the neutron logging cost after boric acid is injected into an oil reservoir. The neutron-gamma log from test measurements was analyzed to identify the gamma spectrums, the relationships between the captured gamma tally and the water saturation, and the relationships between the captured gamma tally and spacing using the Monte-Carlo program MCNP(3B). The exponential attenuation of the captured gamma tally with the water saturation in tests proved the feasibility of the boron neutron-gamma log. Tests show that the borehole hads little influence on the captured gamma tally and that the captured gamma tally is clearly related to the porosity. Theoretical results also show that the neutron-gamma log using the americium-beryllium source can be used to analyze the reservoir characteristics.