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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。
In order to reduce the cost of logging, we replaced the pulsed neutron source with beryllium source, and studied the feasibility of neutron γ logging, ie, neutron γ logging in the condition that the reservoir has been injected with boric acid solution. The Monte Carlo simulation technique, MCNP (3B), was used to calculate the relationship between the capture gamma spectra, capture gamma counts, water saturation and source spacing. It is concluded that the capture γ counts decay exponentially with the increase of water saturation. The borehole has little effect on the capture γ counts, and the correlation between capture γ counts and formation porosity has a good correlation. From the result of calculation, it is feasible to use boron beryllium source instead of pulsed neutron source for boron neutron γ logging, which has strong adaptability and low cost.