川东南官渡气田致密砂岩气藏水相圈闭损害潜力

Potential on aqueous trapping damage of tight sandstone gas reservoirs in Guan-du Gasfield, southeast Sichuan Basin

水相圈闭损害是致密砂岩气藏最致命的损害方式,但由于其损害过程的复杂性,常用的评价方法和指标均具有某些局限性,尚未形成公认的准确预测和评价水相圈闭损害的方法。以四川盆地东南部官渡气田致密砂岩气藏为例,通过地质特征分析和水相毛细管自吸等实验揭示致密砂岩气藏的水相圈闭损害特点,以势能原理为指导,运用势差法评价了致密砂岩气藏的水相圈闭损害程度。分析结果表明,研究区水相圈闭损害总体为中等偏强,且随着储层渗透率降低,水相圈闭指数增加。研究指出,应遵循以预防水相圈闭损害为主,解除损害为辅的原则,各项作业须采取必要措施以尽量减少水基工作液侵入。

Aqueous trapping damage is a fatal way of formation damage to tight sandstone gas reservoirs. Because of the complexity of the damage process,the general evaluation methods and indexes have certain limitations, and the methods for accurately predicting and evaluating the damage degree of the aqueous trapping have not formed yet. Taking tight sandstone gas reservoirs of Cuandu Gas-field in southeast Sichuan Basin as examples,the property of the aqueous trapping damage in the tight sandstone gas reservoirs is revealed by the analysis of geologic characteristics and the experiment of capillary imbibition in water phase. Potential difference method is used to evaluate the damage degree of the aqueous trapping guided by potential energy principle. The results show that the damage degree of the research district is medium to strong in general, and the index of aqueous trapping increases with the decrease of reservoir permeability. The principle should be ' prevention of the aqueous trapping damage as the main measure, damage removal as the supplement measurement'. Some technologies should be adopted in each operation so as to prevent formation damage caused by water based work fluids invasion.