Abstract: In low-permeability reservoirs, stress sensitivity effect is often considered while matrix pore shrinkage effect is ignored, resulting in great errors in the evaluation results of reservoir permeability and productivity. To address the above problems, a mathematical model considering the effects of both stress sensitivity and matrix shrinkage was established with reservoir engineering methods, to explore its feasibility in predicting production performance in the Ansai Oilfield, in combination with a permeability evolution model based on fractal theory. The study showed that under the effective stress below 5 MPa, if the matrix shrinkage effect was ignored, the reservoir permeability was underestimated, which affected the later adjustment of the development plan; the theoretical model established in this paper matched the actual production data by 92%, indicating that the model can better predict the production performance of oil wells in the study area. The study results can be used as an important reference for the late tapping potential and adjustment of similar low-permeability reservoirs in Changqing Oilfield.

Key words: low-permeability reservoir, shrinkage effect, stress sensitivity, pore size, numerical modeling, Ansai Oilfield