TY - JOUR
T1 - Practical considerations for small receive coils in surface NMR
AU - Grombacher, Denys
AU - Liu, Lichao
AU - Larsen, Jakob Juul
AU - Auken, Esben
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/7
Y1 - 2018/7
N2 - The development of multichannel instrumentation was a significant step forward for surface nuclear magnetic resonance (NMR). Multichannel instruments allow data to be recorded on multiple receivers simultaneously, thus facilitating the exploitation of Wiener filtering techniques that provide significant signal-to-noise increases and allow two- and three-dimensional images of the subsurface properties to be produced. When working in challenging environments (e.g. forested/brushy terrain), difficult noise conditions, or when using complicated survey designs it can become quite cumbersome to deploy multiple coils, which often require substantial lengths of cable to be deployed. As such, it would be advantageous if the dimensions of typical receive coils could be greatly reduced from the current standards (~25–100 m). The use of small receive coils would lead to more rapid survey deployment and may advance the utility of methods requiring multiple receivers. The objectives of this work are two-fold. The first aims to quantify limits on the feasible dimensions of small receive coils in surface NMR, aiming to provide an estimate of the minimum effective area of a functional surface NMR receiver. The second aims to demonstrate that the use of multiple additional small receive coils (when used in conjunction with the standard large coincident transmit/receive coil) can help to improve the resolution of estimated water content and relaxation time depth profiles. Synthetic results are presented to quantify lower effective area limits and to demonstrate potential resolution improvements provided by small receivers. The feasibility of a small receiver (400 m2 and 200 m2) is demonstrated in a field setting.
AB - The development of multichannel instrumentation was a significant step forward for surface nuclear magnetic resonance (NMR). Multichannel instruments allow data to be recorded on multiple receivers simultaneously, thus facilitating the exploitation of Wiener filtering techniques that provide significant signal-to-noise increases and allow two- and three-dimensional images of the subsurface properties to be produced. When working in challenging environments (e.g. forested/brushy terrain), difficult noise conditions, or when using complicated survey designs it can become quite cumbersome to deploy multiple coils, which often require substantial lengths of cable to be deployed. As such, it would be advantageous if the dimensions of typical receive coils could be greatly reduced from the current standards (~25–100 m). The use of small receive coils would lead to more rapid survey deployment and may advance the utility of methods requiring multiple receivers. The objectives of this work are two-fold. The first aims to quantify limits on the feasible dimensions of small receive coils in surface NMR, aiming to provide an estimate of the minimum effective area of a functional surface NMR receiver. The second aims to demonstrate that the use of multiple additional small receive coils (when used in conjunction with the standard large coincident transmit/receive coil) can help to improve the resolution of estimated water content and relaxation time depth profiles. Synthetic results are presented to quantify lower effective area limits and to demonstrate potential resolution improvements provided by small receivers. The feasibility of a small receiver (400 m2 and 200 m2) is demonstrated in a field setting.
UR - http://www.scopus.com/inward/record.url?scp=85047093781&partnerID=8YFLogxK
U2 - 10.1016/j.jappgeo.2018.04.005
DO - 10.1016/j.jappgeo.2018.04.005
M3 - Article
AN - SCOPUS:85047093781
SN - 0926-9851
VL - 154
SP - 81
EP - 92
JO - Journal of Applied Geophysics
JF - Journal of Applied Geophysics
ER -