Stress sensitivity of low permeability heterogeneous reservoir and its influences on fluid distribution——taking CO_2-drive oil reservoir as example

Because of the difference of permeability and pore configuration among the layers of heterogeneous reservoir,when the effective pressure changed,the sensitivity of each layer is different,which will certainly influence the distribution of the injected fluid. The stress sensitivity of the low heterogeneous reservoir and its influences on fluid distribution were researched using the parallel core model. The relationship between permeability and effective stress,permeability contrast and effective stress,fluid distribution and effective stress was mainly analyzed according to experiments. Cores with different permeability showed different stress sensitivity when effective stresses were modified,and lower permeability cores showed stronger stress sensitivity than high and moderate permeability ones. With the effective stress increasing,the parameters such as permeability contrast,heterogeneities and throughput ratios in high permeability cores all showed increasing tendencies,while throughput ratios in low permeability cores and swept volume decreased. So,formation pressure should be rational at the development process of low-permeability and heterogeneous oil reservoirs,then the decreased swept volume results from the stress sensitivity would be avoided. Keywordsheterogeneities ;permeability contrast ;effective stress ;stress sensitivity ;fluid distribution