Development of mixed field radiation detection techniques for oil and gas well logging.

2018年1月，NuSec主持的研讨会产生了一份报告，其中强调了开发测井中替代探测和数据解释方法的必要性。谢菲尔德大学的探测器开发小组在μ子、中子和伽马等一系列粒子的探测器开发方面有着悠久的历史。我们最近在STFC的支持下开发了用于含水量监测的中子敏感探测器，这使得我们在内部开发了中子敏感箔制造方面的新专业知识。这种新的能力与以前在CCS监测钻孔探测器原型方面的专业知识相结合。此外，由于与LabLogic的长期合作关系，我们可以使用闪烁体制造设施，从而缩短原型设计和开发周期。沿着我们的中子源（脉冲DT，AmBe，252 Cf）这使我们处于一个独特的位置，能够开发低成本的塑料闪烁体和中子敏感箔为基础的探测系统，用于钻孔配置。通过学生奖学金，我们打算探索使用掺杂有不同材料的闪烁体块来生产精细分段的辐射探测器的可能性，该辐射探测器可以符合标准钻孔与标准方法相比，这种方法有几个优点，例如：使用单个探测器，该探测器使用位置敏感探测/重合来覆盖混合场。- 部署由许多类似堆叠的“模块“或“块”组成的细分探测器意味着系统具有内置冗余;- 从初始中子发生器脉冲到中子/伽马的检测的时间可以提供当使用放射源时不可用的额外的细粒度信息。当前测井技术的另一个问题是，正如论文中所指出的，是数据分析。伽马测井，例如，几乎被用作一种定性的衡量标准。同样，中子孔隙度测量需要进一步校准才能有效。包含脉冲发生器和相关的颗粒检测产生补充信息，然而，这是以额外的处理时间和训练为代价的。对此的解决方案是使用机器学习来提取感兴趣的量，例如，在初始发生器脉冲之后在门控窗口中观察到的来自钻孔检测器的总检测到的中子/伽马计数将用作诸如神经网络的多变量分析（MVA）方法的合适输入。这样的MVA可以通过模拟来训练，以提取相关的感兴趣的量。然后，这些模拟可以使用探测器与谢菲尔德DT源平行放置并被大量材料包围的场景进行实验验证虽然钻孔探测器是本申请的主要硬件焦点，但公认的是，塑料闪烁体与中子的融合是可行的。敏感箔可以在其它应用领域例如环境监测和核工业中提供机会，其中，可能会对采用相同基础技术的替代形式探测器感兴趣。因此，预计项目产出将包括一个可操作的钻孔探测器原型与“标准”（如3 He）方法以及基于MVA的软件工具进行信号鉴别的经验比较。

The NuSec-mediated workshop in January 2018 produced a report in which the need to develop alternative detection and data interpretation methods in well logging was highlighted.The detector development group at the University of Sheffield has a long track record of detector development for a range of particles including muons, neutrons and gammas. Our recent STFC-supported work on the development of neutron-sensitive detectors for water content monitoring has resulted in new expertise in the fabrication of neutron- sensitive foils being developed in house. This new capability sits alongside previous expertise in prototyping borehole detectors for CCS monitoring. Furthermore, due to a long-standing relationship with LabLogic we have access to a scintillator fabrication facility enabling short turnaround prototyping and development cycles. Along with our range of neutron sources (pulsed DT, AmBe, 252Cf) this places us in a unique position to be able to develop low-cost plastic scintillator and neutron-sensitive foil based detection systems for application in borehole configurations.Via the studentship, we intend to explore the possibility of using scintillator blocks doped with different materials to produce finely segmented radiation detectors that can fit down a standard borehole. There are several advantages to this approach over standard methods, e.g.:- use of a single detector that covers mixed fields using position-sensitive detection/ coincidence. On-site expertise in many different detector types is thus not required;- deployment of a finely segmented detector made of many similar stacked "modules"or "blocks" means the system has built in redundancy;- the time from initial neutron generator pulse to detection of neutrons/gammas canprovide additional fine grained information not available when using radiological sources.A further issue with current well logging technologies, as noted in papers, is the analysis of data. Gamma logs, e.g., are used as almost a qualitative measure. Similarly, neutron porosity measurements require further calibration to be effective. The inclusion of pulsed generators and associated particle detection yields supplementary information, however, this is at the cost of additional processing time and training. A solution for this is to use machine learning to extract quantities of interest, e.g. the total detected neutron/gamma counts from a borehole detector observed in a gated window after the initial generator pulse would serve as suitable input to a multivariate analysis (MVA) method such as a neural network. Such an MVA could be trained, via simulations, to extract relevant quantities of interest. These simulations could then be experimentally validated using a scenario in which a detector is placed in parallel with the Sheffield DT source and surrounded by volume of material (e.g. soil and/or rock) of known properties.Whilst the borehole detector is the primary hardware focus of this application it is acknowledged that the fusion of plastic scintillator with neutron-sensitive foils may afford opportunities in other application areas such as environmental monitoring and the nuclear industry, where alternative format detectors employing the same underlying technology may be of interest.The project output is therefore expected to comprise an operational borehole detector prototype with empirical comparisons with "standard" (e.g. 3He) methods as well as MVA-based software tools for signal discrimination.