Research On Weak Gel Flooding Technology Of Zhen-35Block In Jiangsu Oilfield

Block Zhen-35of Jiangsu Oilfield is located in the east wing of Zhenwu Oilfield. It is a NE-trending narrow semi-closed complex fault-block, which is screened by faults on the south, north and west, but open on the east, with the characteristics of high temperature in the reservoir, high salt injection water and strong plane and vertical heterogeneity. Injection water circulates low efficiently and even inefficiently, and water displacement recovery is low because that high capacity channels and preponderant flowing oil layers make injection water flow easily through them, which causes serious fingering, after long time development of water flooding. Thus, it is very urgent to improve development effect of water flooding and enhance oil recovery. The weak gel profile control technique is proposed as a new kind of tertiary recovery, based on profile control by water plugging and polymer flooding. This technique compromising the merits of in-depth profile control and polymer flooding, and playing a dual role of in-depth profile control and oil displacement, is a new kind of flooding system with good effect on oil recovery, which is able to enlarge a sweeping volume in a large scale. So, it has great significance to study weak gel profile control technique and its application in Jiangsu Oilfield.According to the actual demand of development and geology characteristic of reservoir beds, the crosslinking agent appropriate for the water quality and reservoir temperature of Block Zhen35of Jiangsu Oilfield is screened through laboratory determination of gelation behavior in this paper. The concentration of the crosslinking agent and the categories of the additives are optimized, and the formula of weak gel is ascertained by analyzing the effect of temperature, pH value, salinity on compatibility. The thermal stability, the shearing resistance and the dynamic gelling behavior are evaluated in the text. We also evaluated the performance of plugging, turning and flooding of the weak gel system by indoor core simulating test. The result of experiment shows that the developed weak gel profile control system has a good performance of plugging, turning and flooding, which forms the weak gel profile control technique appropriate for Block Zhen35of Jiangsu Oilfield finally.