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- Title
塔里木盆地库车坳陷天然裂缝地质力学响应 对气井产能的影响.
- Authors
张 辉; 尹国庆; 王海应
- Abstract
To understand key factors to productivity in fractured tight sandstone, based on the description of the occurrence of natural fractures and geomechanical modeling, the interaction between in-situ stress and natural fractures was determined, and the normal stress and shear stress of each fracture plane were calculated to compare the relative mechanical response of natural fractures across the anticline structure in the field. We then simulated mechanical response of natural fractures under different pore pressure according to Mohr-Coulomb failure criterion, and obtained the correlation between geomechanical response and openflow rate of gas wells and built the concept of strike-slip rate depending on the theory. At the crest of structure and faulting area, the favorable combination of in-situ stresses and natural fracture strike results in high shear-to-normal stress ratio and higher strike-slip rate and higher production. Reversely, the wells show lower production. And then with the depletion, the dynamic change of mechanical response of natural fractures is also closely related to productivity. Take 3 new wells for example, as pore pressure of reservoir decreases by 10 MPa, productivity of 2 Wells decreases since the shear-to-normal stress ratio of 70%natural fractures decreases, their productivity is still lower than adjacent wells even after fracturing. The productivity of the third well maintains high because the shear-to-normal stress ratio of all natural fractures increases which changes the traditional point that the productivity decreases following the pressure dropping. It is revealed that the geomechanical response of natural fractures is a controlling factor of well productivity in this reservoir. It is a new index for reservoir evaluation, and is also an important supplementary information for optimizing well placement and stimulation program in the special condition.
- Subjects
GAS wells; SHEARING force; RESERVOIRS; STRESS waves; SANDSTONE; DIGITAL image correlation
- Publication
Natural Gas Geoscience, 2019, Vol 30, Issue 3, p379
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2018.10.020