Experiment and Numerical Calculation Study on the Influence of Fracture Deformation to Tight Oil Production

Abstract

Tight oil is a new energy in nearly two decades in the world. Due to the increased demand for energy and enhanced environmental protection awareness, tight oil resources gradually attracted the attention of our government. Tight oil reservoirs usually have extremely low permeability and relatively low porosity, so currently tight oil reservoirs that have been put into industry development often has well developed fracture system with massive fracturing. Fracture system generally has the characteristics of anisotropy and pressure-sensitivity. Therefore, tight oil reservoirs development is extremely complicated. The research of percolation mechanism to tight oil reservoirs is necessary. This paper typically researches anisotropic medium in consider with pressure sensitivity in tight oil reservoir. The similarity criterion for physical simulation experiment in tight oil reservoir is obtained by dimensional analysis. Percolation experiments simulated anisotropic fractured tight oil reservoirs are done by new physical experiment method with similar materials. Ffracture deformation can be observed at low pressure or atmospheric pressure. The percolation mechanism and principle in pressure sensitive deformation and anisotropy fracture medium is revealed. A new fracture deformation characteristics model is established, and this model has strong applicability. With tensor theory and coordinate transformation method, full tensor permeability model of anisotropic fracture medium is established. Based on the established mathematical model, the main factors affecting the development of tight oil reservoirs are analyzed. Full tensor permeability is of ‘rotation effect’ with nonlinear deformation of multiple groups of fractures. The rules of numerical calculation and experimental results are consistent. Fracturing parameters, pressure sensitivity, anisotropy have great impact on the permeability in tight oil reservoirs. Research shows that in the exploitation of tight oil reservoirs, fracture development and reservoir reconstruction in tight oil reservoirs play a significant role in the contribution of tight oil production capacity.