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Evaluation on Stress Sensibility of Low Reservoir in Situ Conditions
SHENG Yingshuai, HU Qingxiong, GAO Hui, SHI Yongmin, DANG Yongchao, SHAO Fei, DU Shuheng, FANG Yuanyuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (6): 1025-1033.   DOI: 10.13209/j.0479-8023.2016.050
Abstract905)   HTML    PDF(pc) (4882KB)(1361)       Save

In order to study the effect of confining press and pore press on permeability, the new method of evaluation on stress sensibility is proposed. Three pieces of low permeable reservoir rock samples in Songliao Basin are selected. A servo-controlled triaxial rock mechanics test system is employed to investigate the permeability of sandstone samples under conventional conditions and in situ conditions. The results show that: 1) The permeability of three pieces of samples reduce with confining press increasing and pore press reducing. 2) The denser the rock is, the stronger stress sensitivity is, in situ conditions, which explains the mechanism of low permeability reservoir sensitivity differences by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), constant speed mercury injection experiment. What’s more, throat size and shape, plastic mineral content and type contribute to the differences of permeability sensitivity. 3) Mineral content and type of plastic are the major factor of the sensitivity of permeability differences. The stress sensitivity of tight reservoir permeability rock becomes strong with the increasement of mica, clay and other plastic mineral content. In the practical work, evaluation on stress sensitivity of permeability, the effect of confining pressure single factor is mostly considered, butthe effect pore presss would be ignored, which is bound to bring larger human error. So evaluation on stress sensibility in situ conditions is essential, which is significant for further understanding of stress sensitivity of low permeability reservoir characteristics and development.

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Nonlinear Characterization Method of Fracturing Stimulation Scale on Heterogeneous Reservoir by Combining Logging and Seismic Data
DU Shuheng, SHI Yongmin, XU Qi, FANG Yuanyuan, SHENG Yingshuai
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (2): 241-248.   DOI: 10.13209/j.0479-8023.2015.079
Abstract1089)   HTML    PDF(pc) (3041KB)(848)       Save

After two infilling adjustment and repeated fracturing on the third type of Chaoyanggou oil field, effective drive systems are still unable to be established in part of the reservoirs, and the measure effect and oil recovery degree is poor. Considering the insufficient understanding on fracture extending and fracturing stimulation scale of heterogeneous reservoir, 3D modeling on reservoir are performed by combining logging and seismic data and the asymmetric cracks are predicted based on elastic theory. Concepts named “relative stress” and “stimulation ratio” are raised, and the nonlinear relation between these two parameters is given. The scale of “relative stress” which could produce the supporting fracture is confirmed, and the fracturing stimulation scale could be judged. It would play important role on the layers selecting during the late development of oilfield and eventually to improve oilfield recovery degree.

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Scattered Sand Rock Mechanics Field Modeling Based on Seismic Pre-stack Inversion
FANG Yuanyuan, SHI Yongmin, WANG Lei, DU Shuheng, SHENG Yingshuai
Acta Scientiarum Naturalium Universitatis Pekinensis    2015, 51 (6): 1040-1046.   DOI: 10.13209/j.0479-8023.2015.075
Abstract1042)      PDF(pc) (1445KB)(964)       Save

For the sake of solving the problem in Daqing Fuyang low permeability reservoirs which is scattered distribution, and changes so rapidly in the mechanical properties of rock that restricts the reservoir reconstruction, a new method was presented in this paper. On the basis of lots of rock mass mechanics model of in situ experiments, the relationship between P-wave and S-wave velocities was studied, and P-wave and S-wave velocity bodies from pre-stack elastic parameter inversion were obtained. Besides, the rock mass mechanics parameters according to rock physics equation were gotten and the multiple regression analysis method was used to get well point elastic parameter values. The well points and cross-hole elastic parameter values were combined, and geostatistics method was utilized to establish the heterogeneity of rock mass mechanics field. The geological basis was provided to optimize hydraulic fracturing parameter design to increase production.

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