| 摘要: |
| 为了研究常规密度测并在套管井中的测井响应特性，应用Mome Carlo方法，从光子与物质相互作用的机理出 发，利用ScWumberger公司的TLD仪器,计算得到了不同套管条件下光子通鼂的能量谱、光子通量与源距和地层电子 密度的关系、长源距计数与短源距计数的交会图以及套管或水泥环厚度对长、短源距计数的影响等。计算结果表 明,当套管和水泥环厚度小于4.4 cm时,常规的TLD密度测井仪器在套管井中对地层密度的变化反应仍然灵敏。 也就是说，在套管井中,密度测井仪器能够测量地层的密度;可以用双源距裸眼井密度测井的补偿原理来处理套管 井密度测井的数据。但在套管井密度测井中,当套管厚度大于一定值后,仪器将难以正确识别地层的岩性。 |
| 关键词: 密度测井 套管 响应特性 Monte Carlo方法 |
| DOI： |
| 分类号: |
| 基金项目:中国石油青年创新基金资助项目(04E7016) |
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| Monte Carlo numerical simulation of response characteristics of compensated density logging in cased hole |
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WU Wen-sheng , XIAO Li-zhi
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(School of Resource and Information Technology in China University of Petroleum, Beijing 102249, China)
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| Abstract: |
| To investigate the response characteristics of traditional density logging tool in cased holes, using TLD density tool of Schlumberger company by Monte Carlo method，photon flux spectrum distribution and the crossplot of long-spacing versus short-spacing count rates were gained based on the mechanism of the interaction between photon and matter. The response relationship between photon flux and spacing，and formation electron-density, the effects of the thickness of casing or cement mantle on long-spacing versus short-spacing count rates were studied. Calculated results show that the traditional TLD density tool is very sensitive to formation density change in cased hole when the thickness of casing or cement mantle is less than 4.4 cm. The traditional density tool can measure formation density in cased hole. The results show that the compensated principle of density logging used in open hole can also be used in cased hole. The formation lithology can't be correctly distinguished using density tool behind casing and cement mantle in cased hole when the casing thickness is greater than a certain value. |
| Key words: density logging casing response characteristics Monte Carlo method |
