Research on Optimized Penetration Ratio Fracturing Technology for Transition Zone

Abstract

The geological reserves of the Sazhong transition zone are 10046×104t, accounting for 12.5% of the Sazhong development zone. The effect of fracturing stimulation in this block is of great significance for the stable production of the Sazhong oilfield. The transition zone has the characteristics of low porosity, low permeability and low oil saturation. The crude oil has three high and one low characteristics: high viscosity, high wax content, high freezing point and low sulfur content. In the transition zone, due to poor physical properties of the oil layer, unbalanced formation pressure, high proportion of low-yield and low-efficiency wells, and energy replacement of thin oil layers, it is difficult to tap the potential of the production increase measures, and the effect of the measures is getting worse year by year. According to statistics, since the transition zone has 40 fractured oil wells since 2009, the fracturing process is general pressure and multi-crack, and the average pressure is 3 layers and 1 slit. The average average sand volume of single seam is 7.1m3, the average sand ratio is 25.7%, and the penetration ratio is only 14.1%. The average initial liquid increase after fracture is 20.4t, and the average initial daily oil increase is only 2.5t. Therefore, the study of transition zone fracturing technology can improve the overall development effect of the block, which is of great significance for the sustainable high yield and stable production of the Sazhong Oilfield.