石油孔固井水泥环属性参数研究与伽马复测系数修正方法

A study of the application parameters of cement ring in oil hole cement in the correction of gamma retargeting coefficient

石油孔老井伽马复测是利用油田作业队在对措施井维修(检泵)取出抽油杆时,利用FD-3019探管进行放射性测量的一种经济实用的方法。进行老井复测时,由于石油钻孔中的固井水泥环对伽马测井结果影响较大,目前伽马测井规范仅有铁水系数修正,而没有水泥环吸收衰减的修正,须经过水泥环属性参数修正,才能正确利用伽马复测资料进行钻孔放射性异常评价。分析认为,固井水泥环主要影响参数为水泥环密度和水泥环厚度,通过制作多个不同厚度不同密度的水泥环模型孔,模拟井下情况,建立模型,利用不同模型水泥环吸收系数值进行拟合,最终找出固井水泥环对伽马测井照射量率的影响系数,并进行修正论证实验,使修正后的数据无限接近地层真实值。文中结合内蒙古某油田区块实际资料,通过水泥环实验测井修正系数,对资料进行修正,探讨了水泥环密度和厚度与照射量率的关系,进一步通过验证孔验证了方法技术的可行性,从而为指导下一步石油老井复测结果提供修正依据。

The gamma retest of the old well in the oil hole is an economical and practical method to measure the radioactivity by FD-3019 probe tube when the oil well maintenance team takes out the sucker rod. Due to the influence of cementing cement ring in oil drilling on gamma logging results, the current gamma logging code has only the correction of molten iron coefficient but no correction of absorption attenuation of cement ring. Therefore, gamma reiteration data can be used to appraise drill radioactive anomaly correctly through the cement ring attribute parameter correction. It is concluded that the main influence parameters of cementing cement ring are cement ring density and cement ring thickness. By making a number of cement ring model holes with different thickness and density, simulating down hole conditions, establishing models and using different model cement ring absorption coefficient values, the authors finally found out the influence coefficient of cementing cement ring on gamma logging illumination rate and carried out correction and demonstration experiments to make the revised data infinitely close to the true formation value. Combined with the actual data of an oil field block in Inner Mongolia, the authors revised the data through the modified coefficient of cement ring experimental logging and discussed the relationship between the density, thickness of cement ring and the irradiation rate. The feasibility of the method is validated by verifying hole technology. The result provides the correction basis for guiding the results of the next re-survey of old oil wells.