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在制订三次采油方案之前,需要精确评价储集层中剩余的含油量。这种方案所涉及的油田,可能在几十年前打过井,而当时的测井方法极为有限,因此在油田内要再钻新井、为全面评价储集层的现状提供机会。本文介绍奥地利毛斯特雷克油田的一口井,评价其注水后的残余油饱和度情况。该井是用经过很好调整的泥浆进行了连续取心,保证了裸眼井测井的最佳条件。配制泥浆,使滤液侵入“均匀”、泥饼很薄、侵入的深度约10～12英寸。泥浆的含盐量和成份都是经过选择了的,使得泥浆滤液的电阻率等于注水前原始地层水的电阻率。因为地层水稍淡,而且本方法要求用裸眼井热中子衰减时间测井的读数提供计算,所以在泥浆中要添加硼酸,以提高泥浆滤液的核俘获截面,从而使热中子衰减时间测井对侵入带含水饱和度更加灵敏。裸眼井测井项目包括双侧向、微球形聚焦测井、补偿中子测井、地层密度测井、自然伽玛测井和热中子衰减时间测井。通过将微电阻率测井与热中子衰减时间测井二者结果的比较进行计算机处理评价。调整各种参数;直到这两种结果一致为止。最后的结果再与岩心孔隙度和饱和度进行对比。
Before formulating a tertiary recovery program, the remaining oil content in the reservoir needs to be accurately evaluated. The oilfields involved in such a scheme may be able to hit the well decades ago with very limited well logging methods at the time. Therefore, drilling new wells within the oilfield would provide an opportunity to fully evaluate the status of the reservoir. This article describes a well in the Maurit-Drake field in Austria and evaluates the residual oil saturation after water injection. The well was continuously cored with well-tuned mud to ensure the best conditions for open-hole logging. Mud preparation, the filtrate invading “uniform”, mud cake is very thin, the depth of invasion of about 10 to 12 inches. The salt content and composition of the mud are chosen so that the resistivity of the mud filtrate is equal to the resistivity of the original formation water before water injection. Because formation water is light and the method requires calculations using open-hole thermal neutron decay time log readings, boric acid is added to the slurry to increase the nuclear capture cross-section of the mud filtrate so that the thermal neutron decay time Wells are more sensitive to invaded zone water saturation. Open-hole logging programs include bi-lateral, microsphere-focused logging, compensated neutron logging, formation density logging, gamma ray logging and thermal neutron decay time logging. The computer processing evaluation was made by comparing the results of both the micro-resistivity log and the thermal neutron decay time log. Adjust various parameters; until these two results are consistent. The final result is compared with core porosity and saturation.