Water shut off in a horizontal well: Lab experiments with starch graft copolymer agent

A kind of starch graft copolymer (SGC) water shut off agent, a novel, efficient and economic crude macromolecular plugging agent, has been applied to some oilfields. In this paper, a three dimensional physical model of horizontal well was designed for the water shutoff with an edge water simulating the edge water driving reservoir and with a higher permeability band imitating the preferential paths. Using the model and X-ray computed tomography (CT), the effect of blocking the water channeling paths on the model taken by starch strong gels blocking agent was tested. The result showed that the agent was selective and got a good effect. Besides, a simple Computer Modeling Group (CMG) model was used to deduce the development process of the water breakthrough, channeling, and flooding, so as to explain previously what had happened in the physical model. Finally, compared to field experiment, the advance of the model lies in that it can be used in performance appreciation of water shut off agent well.