The community diversities of two oil reservoirs with low permeability of 1.81 × 10−3 and 2.29 × 10−3 μm2 in Changqing, China, were investigated using a high throughput sequencing technique to analyze the influence of biostimulation with a nutrient activator on the bacterial communities. These two blocks differed significantly in salinity (average 17,500 vs 40,900 mg/L). A core simulation test was used to evaluate the effectiveness of indigenous microbial-enhanced oil recovery (MEOR). The results indicated that in the two high salinity oil reservoirs, one reservoir having relatively lower salinity level and a narrow salinity range had higher bacterial and phylogenetic diversity. The addition of the nutrient activator increased the diversity of the bacterial community structure and the diversity differences between the two blocks. The results of the core simulation test showed that the bacterial community in the reservoir with a salinity level of 17,500 mg/L did not show significant higher MEOR efficiency compared with the reservoir with 40,900 mg/L i.e. MEOR efficiency of 8.12% vs 6.56% (test p = 0.291 > 0.05). Therefore, salinity levels affected the bacterial diversities in the two low permeability oil blocks remarkably. But the influence of salinity for the MEOR recovery was slightly.

Indigenous microbial enhanced oil recovery (IMEOR) has been successfully applied in conventional oil reservoirs, however the mechanism in low-permeability oil reservoirs is still misunderstood.

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Mechanical properties and microstructural evolution of an Al-Cu-Mg-Ag alloy during thermal exposure at elevated temperature were characterized by means of tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The tensile test results suggested that tensile strength ( ) and yield strength ( ) reduced with both increasing exposure time and temperature. Correspondingly elongation of samples increased steadily with increasing exposure time and temperature, which resulted in ductile fracture. TEM results suggested the reduction of mechanical property of samples was attributed to coarsening and reduction in amount of dominant strengthening phase-Ω phase during thermal exposure.

H2S existed in some oil-gas field, resulting in many drill pipe hydrogen embrittlement and stress corrosion cracking accident during the drilling, causing huge losses, particularly during blowout and pipe fall into the bottom caused by hydrogen embrittlement, would lead to serious accident .There were a lot examples in history, in view of the situation, this paper analyzed of the mechanism of the hazards of H2S to the drill pipe, proposed the technical conditions and using requirements to select anti-sulfur drill pipe. After field using, selecting the proper types of anti-sulfur drill can improve the safety of drilling. According to field application summed some attention in the process of using the anti-s drill issue to be aware of.