A review on the applications of the nuclear magnetic resonance (NMR) technology for investigating fractures

• We reviewed applications of NMR technology for investigating fractures.
• The most important principle is separating fracture porosity from matrix pore porosity.
• The techniques for achieving this purpose are not extensively developed yet.
• These techniques would lead to considerable impacts in unconventional resources.

This review focuses on the recent applications of nuclear magnetic resonance (NMR) technology for characterizing fractures. The paper aims to help researchers in extending the existing reservoir characterization methods (which are commonly used in conventional hydrocarbon reservoirs) for appropriate usage in unconventional resources. This is because some techniques for quantifying and qualifying fractures have been investigated in conventional sandstone and carbonate reservoirs, but the reality for unconventional resources is that such techniques are still poorly developed. Fractures are necessary for economical production of petroleum from many low-permeability reservoirs. The characterization of fractures by well logging technology is of great interest in the petroleum industry. The main purpose of this study is to review the characterization techniques that are developed either for identifying fractures or distinguishing fracture porosity from matrix porosity. This concept plays a leading role in providing availability of an optimized well completion program. The results of this study indicated that in terms of both sandstone and carbonate tight reservoirs, there have not been many steps taken toward the aforementioned goal up to now. Nevertheless, these steps are valuable enough to be counted on and could serve a meaningful function in treating hydrocarbon reservoirs. Because of the ongoing changes in today's petroleum industry, development of a comprehensive methodology will create greater economic benefits in unconventional reservoirs than in the conventional ones.