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PurposeTo compare the effect of conventional pedicle screw (CPS) and cement-augmented pedicle screw instrumentation (CAPSI) on adjacent segment degeneration (ASD).MethodsA normal male volunteer without a history of spinal disease was selected, lumbar CT data was collected, an intact L3-S1 three-dimensional finite element model was created by software including Mimics, Geomagic, and SolidWorks, and the fixation methods were performed accordingly. A common pedicle screw model and a cement-augmented pedicle screw model of L4–L5 with fusion and internal fixation were constructed. With ANSYS Workbench 17.0, a 500 N load was applied to the upper surface of L3 to simulate the weight of a human body, and a 7.5 N m moment was applied at the neutral point to simulate flexion, extension, left/right bending, left/right rotation of the spine. The peak von Mises stress of intervertebral disc and the range of motion (ROM) on the adjacent segments (L3–4 and L5–S1) were compared.ResultsThe validity of the intact model shows that the ROM of the model is similar to that of a cadaveric study. Compared with the intact model, CPS model and CAPSI model in all motion patterns increased the ROM of adjacent segments. The intervertebral disc stress and the ROM of adjacent segments were found to be higher in the CAPSI model than in the CPS model, especially in L3–4.ConclusionIn general, the biomechanical analysis of an osteoporotic lumbar spine showed that both CPS and CAPSI can increase the ROM and disc stresses of osteoporotic lumbar models, and compared with CPS, CAPSI is more likely to increase the potential risk of adjacent segment degeneration.

Considering the reservoir seepage, borehole wall inflow, fracture and perforation flow’s process and mutual influence, an unsteady state computation model of fractured horizontal well coupling with reservoir was established based on the source function and superposition principle. Calculation results showed that compared to the production only from the hydraulic fractures, the difference of that both from fractures and perforations was great early and decreased slowly later. Take the perforation production for example, because of mutual interference and well bore flow friction, different location perforations with different output and the central-perforation production was lower than that of the outer-position.

Due to the differences of stress and physical property in the pay zone, the fractured horizontal well may be different in length and azimuth angle. Furthermore, because of the mutual disturbance among fractures, the accurate prediction of production of fractured horizontal wells become more complicated. This paper presents a new model to predict the production of the fractured horizontal wells by considering the effects of fracture number, fracture length, fracture interval, fracture symmetry, azimuth angle and conductivity. Compared with the numerical simulation, this model needs less parameter and calculating time, and is easy to be applied to the designs of segmentation fracturing in horizontal wells. The model in this paper has been applied to the optimizing designs of hydraulic fracturing for two horizontal wells in North China oilfield and the predicted results agree with the actual production well.

In this paper, the fragmentation of fuzzy numbers is defined as new sort indicators Based on the Centroid and fragmentation of fuzzy numbers, paper proposes a new ranking method of fuzzy numbers which can overcome the shortcomings of some ranking method to some degree. At last, paper illustrates the practicability of the proposed method by the analysis of examples.