NMR serves as an important technique for probing rock pore space, such as pore structure characterization, fluid identification, and petrophysical property testing, due to the reusability of cores, convenience in sample processing, and time efficiency in laboratory tests. In practice, NMR signal collection is normally achieved through polarized nuclei relaxation which releases crucial relaxation messages for result interpretation. The impetus of this work is to help engineers and researchers with petroleum background obtain new insights into NMR principals and extend existing methodologies for characterization of unconventional formations. This article first gives a brief description of the development history of relaxation theories and models for porous media. Then, the widely used NMR techniques for characterizing petrophysical properties and pore structures are presented. Meanwhile, limitations and deficiencies of them are summarized. Finally, future work on improving these insufficiencies and approaches of enhancement applicability for NMR technologies are discussed.

Hydrajet fracturing has the advantages which not only include perforating without compacted zone, creating fracture exactly, but also include controlling fracture height, shortening the working cycle, reducing operation risk and etc.[. Through studying the optimization of nozzle materials and combination, string structure, operation pressure of surface casing and annular displacement, the hydraulic jet multistage fracturing technology is formed. This technology is successfully used and proves it has good popularization and application.

In this paper, the FDM-Program FLAC3D is used for the 3D simulation of fracture propagation on a field scale model, based on field data of a Rotliegend tight gas reservoir in North Germany. This reservoir was treated hydraulically by a massive fracturing. The results regarding the fracture propagation were compared with those in the semi-analytical P3D simulator FracPro. It was noticed that the original code FLAC3D was unsuitable for the applications of hydraulic fracture. In further investigations, our own developed algorithm with a moving boundary condition based on discontinuum mechanics was implemented in FLAC3D. The results showed a relatively good agreement with those of FracPro. The advantage of the new algorithm is above all that irregular fracture front can be realistically simulated, which in turn reflects the stress states in multi-layers and their different rock mechanical properties

Aiming at the southern areas of Bohai glutenite reservoir natural capacity is low, without obvious interlayer, filter lost badly, cause conventional hydraulic facturing in short of effect on increasing production, the paper conducted the research and application of technology on Y104-6 well. According to the reservoir geological characteristics and well conditions, the paper studied on fracturing scale determination, the perforating section, and the optimization of fracturing material selection, and application. Completed the injection into well fluid amount 1491.9 m3, proppant 188 m3, displacement of pump 7.5 m3/min. After treatment, average fluid flowing production achieved 18.6 t/d, average daily oil production 6.8 t, stimulate effect and the economic benefit is remarkable. This well fracturing technology, make the successful application of the southern areas of Bohai glutenite reservoir a significant breakthrough, recoverable reserves get promoted for big thick section glutenite reservoir development and vertical fracturing of the organization and implementation has provided valuable experience.