Study On Deep Flooding System Of Self-generating Gas Gel-foam

There are serious reservoir heterogeneity and loose cementing in the conventional heavy oil sandstone offshore reservoirs of Bohai Bay.As a result of long-term traditional waterflood development,the planar and longitudinal heterogeneity of reservoirs has been severe,resulting in a rapid increase of water cut in oilfield development,output decrease and other problems.In view of the above problems,this paper proposes a plugging system with good sealing performance and suitable for Bohai oilfield,which is of great significance to exploitation of offshore heavy oil sandstone reservoirs.In this paper,the gas generation efficiency is set as an indicator of the optimal selection of self-generating gas,and NaNO₂+NH₄Cl system was selected at last.Based on this,the influence of temperature and pressure on the gas generation efficiency was studied,as well as the exothermic reaction of gas generation.And regulation of the reaction rate by catalyst was also achieved.The gelatin time and gel strength of the jelly were evaluated,and finally a kind of Cr³⁺-phenolic resin composite jelly was formulated,this kind of composite jelly is of good strength,and gelling time is adjustable from 11h to 62h,which is able to meet the requirements of the deep flooding.Through the experiment,the stability of the composite jelly and the effects of reaction exotherm and gas generation on the jelly properties were studied.Through the static and dynamic indicators,foam was evaluated and the formula of foam system was determined.In the meantime,in each chapter,the mutual influence between self-generating gas,gel and foam was studied.Finally,the formulation of self-generating gas gel-foam was determined.The plugging performance of the system and the ability to improve oil recovery were evaluated.The experimental results showed that compared with the general self-generating gas strengthened foam,this system is of excellent plugging performance,which is able to improve formation heterogeneity for a long time and significantly enhance the oil recovery.