随钻D-T源孔隙度测井中的钻铤影响机制  

Influence mechanism of drill collar in D-T porosity logging while drilling

作　　者：张泉滢 李宁超 张凤姣 聂昕[2] 宋红伟[2] 刘国斌 ZHANG Quanying;LI Ningchao;ZHANG Fengjiao;NIE Xin;SONG Hongwei;LIU Guobin(Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University),Ministry of Education,Wuhan 430100,China;College of Geophysics and Petroleum Resources,Yangtze University,Wuhan 430100,China;SINOPEC Matrix Corporation,Qingdao 266071,China)

机构地区：[1]油气资源与勘探技术教育部重点实验室(长江大学),湖北武汉430100 [2]长江大学地球物理与石油资源学院,湖北武汉430100 [3]中石化经纬有限公司,山东青岛266071

出　　处：《中国石油大学学报（自然科学版）》2024年第6期68-77,共10页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(42474159);油气资源与勘探技术教育部重点实验室(长江大学)开放基金项目(K2023-03,PI2023-03)。

摘　　要：基于数值模拟方法剖析钻铤改善中子孔隙度测井灵敏度的机制,并仿照钻铤影响提出中子源减速块和探测器屏蔽套等结构用于设计高灵敏度电缆D-T源孔隙度仪器。结果表明:探测器附近钻铤能屏蔽来自井眼方向的热中子,提高来自地层的热中子信息比重,进而改善测井灵敏度;中子源附近钻铤会降低进入地层的高能快中子平均能量,使得仪器对中、低孔地层的灵敏度提高;中子源减速块和探测器屏蔽套等结构可以代替钻铤改善中子孔隙度的测井灵敏度,为D-T源在电缆测井中的应用提供理论指导。This paper investigates the mechanism by which a drill collar enhances the sensitivity of D-T source porosity logging using numerical simulation methods and discusses the design scheme for a high-sensitivity wireline D-T source porosity tool based on this mechanism.This study reveals that the drill collar near the detector absorbs thermal neutrons from the borehole direction,increasing the proportion of formation information in the detected signal and thereby improving logging sensitivity.Additionally,the drill collar near the D-T source reduces the average energy of fast neutrons entering the formation,enhancing the porosity sensitivity of the logging instrument,particularly in formations with medium and low porosity.Based on this influence mechanism,new structural features,such as a neutron-source deceleration block and a detector shielding sleeve,were incorporated into the design of the wireline D-T source porosity logging tool,significantly enhancing its porosity sensitivity.This research provides theoretical guidance for the application of D-T sources in wireline logging.

关 键 词：D-T源 中子孔隙度测井 钻铤影响机制 测井灵敏度 数值模拟 

分 类 号：P631.9[天文地球—地质矿产勘探]