储层压力下氮气泡沫封堵性能影响因素研究

Influencing Factors of Nitrogen Foam Plugging Performance Under Reservoir Condition

储层压力对泡沫产生的封堵能力影响较大。为了研究泡沫在实际储层压力下封堵性能的影响因素,实验设置10MPa的回压模拟泡沫生成的环境压力,以氮气作为气相介质研究储层压力、气液比、渗透率、含油饱和度、地层倾角等对泡沫封堵性和稳定性的影响。实验结果表明,储层压力影响泡沫的封堵性能,压力越大泡沫产生的阻力效应越小。在一定的储层压力下,存在最佳的气液比,使得泡沫产生的阻力效应最强。储层的孔隙结构影响泡沫的存在形态,渗透率越高的储层中泡沫的封堵作用越强。低含油饱和度情况下,泡沫仍能产生一定的封堵作用,但是封堵有效期很短,因此氮气泡沫可以在低含油饱和度储层中形成暂时封堵。泡沫在存在倾角的储层中更易均匀分布,产生的封堵阻力越高,同时也说明泡沫在垂向上的封堵能力更佳。

The plugging performance of the foam is strongly affected by the environment pressure. The back pressure is set to 10 MPa to simulate the environment pressure of the foam, in order to study the influencing factors of the plugging performance of the foam under the reservoir pressure. The nitrogen is chosen as the gas phase medium. The influencing factors studied in this paper include the reservoir pressure, the gas liquid ratio, the permeability, the oil saturation and the dip angle. It is shown that the plugging performance of the nitrogen foam is affected by the reservoir pressure. The greater the reservoir pressure is, the smaller the resistance effect will be. Within a certain range, the higher the gas liquid ratio of foam is, the better the plugging performance will be. The pore structure of the reservoir affects the generation of the foam, so that the higher the permeability is, the higher the plugging ability of the foam will be. Under the condition of a low oil saturation, the foam still has a certain plugging effect. But because the plugging period of a valid foam is very short, the nitrogen foam can only have a temporary plugging effect in the low oil saturation reservoir. The nitrogen foam is better distributed in the angle reservoir, where the plugging resistance of the nitrogen foam is higher. In the meantime, it is indicated that the plugging performance of the foam is better in the vertical direction.