一种基于随钻核磁共振时移测井的气层物性参数评价方法

An Gas Reservoir Evaluation Method of LWD NMR Logging Based on Time-Lapse Logging

水平井气层孔隙度评价一直是海上气田开发的难题之一,通过核磁共振测井理论分析和岩心侵入实验研究,提出了随钻核磁共振时移测井校正方法。研究认为,在一定时间内,目标区储层的钻井液滤液侵入深度可达10 cm以上,通过随钻核磁共振测井和时移复测,能够求取随钻实时测量时的流体含氢指数H_(i)。建立H_(i)与随钻核磁共振孔隙度的关系式,可以对全井段核磁共振孔隙度进行校正,得到相对真实的储层孔隙度;也可以通过直接建立实测孔隙度和复测孔隙度之间的关系式,求取全井段孔隙度值。此方法的优点是在兼顾资料录取质量的同时减少作业时间、降低成本,在多口井应用效果良好,具有一定借鉴意义。

The reservoir porosity evaluation of horizontal well is one of the problems in the development of offshore gas fields.Through nuclear magnetic resonance(NMR)logging theory analysis and core intrusion experimental research,a correction method of NMR time-lapse logging while drilling is proposed.The research shows that the depth of the mud filtrate intrusion can reach more than 10 cm in a certain period of time.Through the NMR logging while drilling and time-lapse retesting,the reservoir hydrogen index H_(i)can be obtained.The relationship between the hydrogen index H_(i)and the NMR porosity while drilling can be used to correct the NMR porosity of the whole well,thus obtaining relatively true reservoir porosity.It is also possible to obtain the porosity value of the whole well by directly establishing the mathematical relationship between the porosity while drilling and the porosity of the retest.The advantage of this method is that while taking into account the quality of data admission,it can reduce the operation time and cost,and the application effect of multiple wells is good,which has certain reference significance.