Application and experimental study of cyclic foam stimulation

Abstract

Formation damage is a serious problem in oil and gas industries. Based on common reservoir damage, the conditions and factors resulting in damage were summarized into four categories in this paper. The worldwide advanced technologies applied in reservoir damage treatment are reviewed. For the first time, we propose the concept of injecting nitrogen foam into a formation to treat the damage caused by sand blocking. An application of Cyclic Foam Stimulation is introduced, which enhances productivity significantly. Experimental apparatus for the Cyclic Foam Stimulation was designed, which included a wellbore vessel that could stimulate the effect of sand setting. A reservoir vessel was also designed to supply the foam. Additionally, in order to simulate the formation damage caused by the size and distribution of fine sand, six artificial cores, which were porosity contrastive and sand producing, were prepared based on the technologies of pressure control and PVA membrane wrapping. The experimental results show that the foam has a good discharging effect on sand blockages. Moreover, the effects of the size and distribution of the fine sand on the porosity was studied. It was found that the smaller the size of the grains and the more uniform the grain distribution, the worse the formation porosity. A porosity recovery factor has been defined and the recovery rate of the porosity was also studied. A scientific guide for the application of Cyclic Foam Stimulation can be generated from the studies in this paper.